Examkin

All practice questions

2583 questions

All types13,931Multiple choice7,139True / False771Numeric1,526Matching2,583Ordering631Fill in the blank1,223Short answer58
Question 2341Question →

Match each physical component or thermal phenomenon listed on the left with its corresponding primary heat transfer mechanism and operational principle on the right.

Click a left item, then click its matching right item

Items

Evacuated space between double walls of a vacuum flask
Silvered inner glass surfaces of a vacuum flask
Thick copper base of a metallic cooking vessel
Offshore land breeze occurring in coastal regions at night

Matches

Show answer & explanation

Answer

The correct pairings are: the evacuated space matches the prevention of conduction and convection due to lack of medium; silvered inner glass matches the minimization of radiation via reflective low-emissivity surfaces; the thick copper base matches enhanced conduction via free electron diffusion; and the offshore land breeze matches natural convection driven by air density differences.
Each phenomenon is matched correctly to its fundamental physical requirement: vacuum interspace eliminates conduction and convection by removing matter; silvered surfaces prevent radiation loss via reflection; copper base accelerates conduction through electron movement; land breeze is a fluid density-driven convection current.

Step-by-Step Solution

1
Analyze the vacuum interspace mechanism
Since conduction requires direct particle collisions and convection requires fluid flow, removing air creates a vacuum that eliminates both conduction and convection.
Both conduction and convection depend on a physical medium.
2
Analyze the silvered glass walls function
Radiation does not require a medium and is governed by surface emissivity. Shiny, silvered surfaces reflect thermal radiation back into the vessel.
Polished metallic coatings decrease thermal radiation emissivity and increase reflectivity.
3
Analyze the copper cooking base conduction property
Metals like copper transfer heat rapidly across solid structures using free electrons alongside atomic lattice vibrations.
Free electron diffusion makes copper an exceptionally good conductor of heat.
4
Analyze the coastal land breeze phenomenon
At night, land loses thermal energy faster than water, causing cooler dense air above land to slide under warmer rising air over the sea.
This fluid circulation driven by thermal expansion and buoyancy differences is natural convection.

Key Concept

Distinct physical requirements and microscopic mechanisms of conduction, convection, and thermal radiation.
Estimated Time:2m 0s
Question 2342Question →

Match each characteristic functional group structure listed on the left with its corresponding organic class name on the right.

Click a left item, then click its matching right item

Items

−NH2-\text{NH}_2
−CONH2-\text{CONH}_2
−O−-\text{O}-
−COOR-\text{COOR}

Matches

Show answer & explanation

Answer

The correct pairings are: −NH2-\text{NH}_2 matches with Primary amine, −CONH2-\text{CONH}_2 matches with Amide, −O−-\text{O}- matches with Ether, and −COOR-\text{COOR} matches with Ester.
Each organic compound class is identified by its specific functional group arrangement: −NH2-\text{NH}_2 specifies primary amines, −CONH2-\text{CONH}_2 specifies primary amides, an oxygen atom bridging two carbon groups (−O−-\text{O}-) specifies ethers, and −COOR-\text{COOR} specifies esters.

Step-by-Step Solution

1
Identify the amino functional group
−NH2-\text{NH}_2 is recognized as an amino group attached to a carbon chain.
Compounds containing the −NH2-\text{NH}_2 group attached directly to an alkyl carbon belong to the class of primary amines.
2
Identify the carboxamide functional group
−CONH2-\text{CONH}_2 contains a carbonyl bonded to an amino group.
This structural unit defines the primary amide family.
3
Identify the ether linkage
−O−-\text{O}- represents a single oxygen atom bridging two carbon atoms.
An oxygen atom connected to two alkyl or aryl groups (R-O-R’\text{R-O-R'}) characterizes an ether.
4
Identify the ester group
−COOR-\text{COOR} contains a carbonyl carbon attached to an alkoxy group.
This group is derived from an alkanoic acid and an alkanol, forming an ester.

Key Concept

Identification of characteristic functional groups in organic compounds
Question 2343Question →

Match each organic functional group class on the left with its corresponding characteristic IUPAC suffix on the right.

Click a left item, then click its matching right item

Items

Carboxylic acid (−COOH-\text{COOH})
Acid amide (−CONH2-\text{CONH}_2)
Acyl chloride (−COCl-\text{COCl})
Ester (−COOR-\text{COOR})

Matches

Show answer & explanation

Answer

Carboxylic acid matches '-oic acid', Acid amide matches '-amide', Acyl chloride matches '-oyl chloride', and Ester matches '-oate'.
Each organic class is correctly matched to its IUPAC principal suffix: carboxylic acids use '-oic acid', amides use '-amide', acyl chlorides use '-oyl chloride', and esters use '-oate'.

Step-by-Step Solution

1
Identify the characteristic functional group structure for each carbonyl derivative class.
Carboxylic acids have −COOH-\text{COOH}, amides have −CONH2-\text{CONH}_2, acyl chlorides have −COCl-\text{COCl}, and esters have −COOR-\text{COOR}.
Functional groups define the chemical family and dictate IUPAC naming rules.
2
Pair each class with its designated IUPAC principal suffix.
−COOH→-oic acid-\text{COOH} \rightarrow \text{-oic acid}, −CONH2→-amide-\text{CONH}_2 \rightarrow \text{-amide}, −COCl→-oyl chloride-\text{COCl} \rightarrow \text{-oyl chloride}, and −COOR→-oate-\text{COOR} \rightarrow \text{-oate}.
Standard IUPAC rules assign specific characteristic suffixes to represent the main functional group in systematic names.

Key Concept

IUPAC Nomenclature Suffixes for Carbonyl Derivatives
Question 2344Question →

Match each specific electronic structure scenario or electron assignment with the corresponding quantum principle or thermodynamic factor that governs it.

Click a left item, then click its matching right item

Items

The ground-state electron configuration of copper being [Ar]3d104s1[Ar]3d^{10}4s^1 rather than [Ar]3d94s2[Ar]3d^9 4s^2
The impossibility of two electrons in an atom having the identical quantum set (2,1,−1,+12)(2, 1, -1, +\frac{1}{2})
Nitrogen placing one electron in each of the 2px2p_x, 2py2p_y, and 2pz2p_z orbitals with parallel spins
Filling the 4s4s subshell (n+l=4n+l=4) before commencing the filling of the 3d3d subshell (n+l=5n+l=5)

Matches

Show answer & explanation

Answer

The correct pairings match copper's anomalous configuration to full-subshell exchange energy stability, identical quantum set restriction to the Pauli exclusion principle, unpaired degenerate orbital filling in nitrogen to Hund's rule, and 4s4s filling prior to 3d3d to the Aufbau (n+l)(n+l) principle.
Each scenario directly aligns with its foundational quantum principle: copper's ground-state configuration ([Ar]3d104s1[Ar]3d^{10}4s^1) is stabilized by high exchange energy of the full dd-subshell; identical quantum numbers are forbidden by the Pauli exclusion principle; single filling of degenerate 2p2p orbitals in nitrogen obeys Hund's rule of maximum multiplicity; and subshell filling order (4s4s before 3d3d) is governed by the Aufbau (n+l)(n+l) rule.

Step-by-Step Solution

1
Analyze the copper configuration anomaly ([Ar]3d104s1[Ar]3d^{10}4s^1).
Identified as a deviation due to exchange energy stabilization of a completely filled dd subshell.
Completely filled subshells provide enhanced stability via maximum exchange interactions and spherical symmetry.
2
Examine the prohibition of identical four-quantum-number sets (n,l,ml,ms)(n, l, m_l, m_s).
Identified as a direct statement of the Pauli exclusion principle.
Two electrons in an orbital must have opposite spin quantum numbers (+12+\frac{1}{2} and −12-\frac{1}{2}).
3
Evaluate nitrogen's 2p32p^3 configuration (2px12py12pz12p_x^1 2p_y^1 2p_z^1).
Identified as an application of Hund's rule of maximum multiplicity.
Electrons occupy degenerate subshell orbitals singly with parallel spins to minimize inter-electronic coulomb repulsion.
4
Assess the sequence of filling 4s4s prior to 3d3d.
Identified as following the Aufbau principle via the (n+l)(n+l) rule.
For 4s4s, n+l=4+0=4n+l = 4+0 = 4; for 3d3d, n+l=3+2=5n+l = 3+2 = 5. Lower (n+l)(n+l) subshells fill first.

Key Concept

Quantum Rules, Subshell Energies, and Electronic Configuration Anomalies
Question 2345Question →

Match each physical electromagnetic configuration listed under Column I with its corresponding net magnetic force or motion characteristic listed under Column II.

Click a left item, then click its matching right item

Items

A charged particle projected parallel to the lines of a uniform magnetic field
Two long, straight parallel conductors carrying electric currents in opposite directions
A current-carrying rectangular wire coil positioned with its plane parallel to a uniform magnetic field
A charged particle injected perpendicularly into a uniform magnetic field

Matches

Show answer & explanation

Answer

1. Charged particle moving parallel to magnetic field lines →\rightarrow Experiences zero magnetic force (F=0F = 0) and maintains its initial linear trajectory.
2. Parallel conductors carrying opposite currents →\rightarrow Experience a mutually repulsive force per unit length given by FL=μ0I1I22πd\frac{F}{L} = \frac{\mu_0 I_1 I_2}{2\pi d}.
3. Current-carrying rectangular coil parallel to magnetic field →\rightarrow Experiences maximum net magnetic torque (τ=NIAB\tau = N I A B) while net translational force is zero.
4. Charged particle injected perpendicularly into magnetic field →\rightarrow Follows a uniform circular path due to a constant magnetic centripetal force (F=qvBF = qvB).
Each electromagnetic system is correctly paired based on the vector cross-product rules governing magnetic force (F=q(v×B)F = q(\mathbf{v} \times \mathbf{B}) and F=I(L×B)F = I(\mathbf{L} \times \mathbf{B})). Parallel motion produces zero force due to zero angle; opposite currents repel per unit length according to Ampère's law; a parallel loop experiences maximal couple/torque without linear displacement; and perpendicular particle velocity results in a constant centripetal deflection into circular motion.

Step-by-Step Solution

1
Analyze the angle θ\theta between velocity and magnetic field for a parallel moving charge
Since velocity is parallel to the field, θ=0∘\theta = 0^\circ. The magnetic Lorentz force formula F=qvBsin⁡θF = qvB\sin\theta yields F=0F = 0, meaning no deflection occurs.
Magnetic forces require a non-zero perpendicular component of motion relative to the magnetic field direction.
2
Determine the interaction force between parallel conductors with opposite currents
By applying the magnetic field rule for long straight conductors and Fleming's left-hand rule for the resulting force, currents flowing in opposite directions repel each other with force per unit length FL=μ0I1I22πd\frac{F}{L} = \frac{\mu_0 I_1 I_2}{2\pi d}.
Opposite current directions generate magnetic field lines between the wires that reinforce each other, creating a high-density magnetic field region that pushes the conductors apart.
3
Evaluate forces and torque on a rectangular coil aligned parallel to magnetic field lines
The forces on opposite arms are equal in magnitude and opposite in direction, canceling out net linear translation (Fnet=0F_{\text{net}} = 0). However, they act along different lines of action, producing a maximum torque τ=NIABcos⁡0∘=NIAB\tau = N I A B \cos 0^\circ = N I A B.
Maximum torque occurs when the plane of the coil is parallel to the field because the lever arm for the magnetic forces on the side conductors is at its maximum length.
4
Evaluate the trajectory of a charged particle entering perpendicularly into a magnetic field
At θ=90∘\theta = 90^\circ, sin⁡90∘=1\sin 90^\circ = 1, giving a constant magnetic force F=qvBF = qvB. Because vector force is perpendicular to velocity at every instant, it changes only the direction of velocity, driving the particle into a circular orbit of radius r=mvqBr = \frac{mv}{qB}.
A constant magnitude force acting perpendicular to the instantaneous velocity vectors fulfills the exact condition for centripetal acceleration.

Key Concept

Magnetic forces on moving charges and current-carrying conductors under specific geometric alignments and current configurations
Estimated Time:3m 0s
Question 2346Question →

Match each physical analytical observation of a chemical sample with its corresponding interpretation regarding purity.

Click a left item, then click its matching right item

Items

A solid sample exhibits a sharp melting point at exactly 156.5∘C156.5^\circ\text{C}.
A solid sample melts over a broad temperature range of 142.0∘C142.0^\circ\text{C} to 150.5∘C150.5^\circ\text{C}.
A liquid sample boils at a steady temperature higher than the literature value of the pure solvent.
Paper chromatography of a dye sample produces a single spot under varied solvent systems.

Matches

Show answer & explanation

Answer

1. Solid with a sharp melting point at 156.5∘C156.5^\circ\text{C} matches 'Confirms the sample is a pure crystalline compound'.
2. Solid melting over 142.0∘C142.0^\circ\text{C} to 150.5∘C150.5^\circ\text{C} matches 'Indicates the presence of impurities that depress and broaden the melting point'.
3. Liquid boiling at a steady temperature higher than literature value matches 'Indicates the presence of a non-volatile dissolved impurity in the liquid'.
4. Single spot on paper chromatography matches 'Demonstrates chemical homogeneity and single-component composition'.
Pure compounds exhibit constant physical properties such as sharp melting points, constant boiling points, and single chromatographic spots. Impurities alter lattice stability and vapor pressure, leading to melting point depression, boiling point elevation, and broad temperature transition ranges.

Step-by-Step Solution

1
Analyze solid sample melting characteristics
A sharp melting point indicates high purity, while a broad melting range below the expected temperature indicates contamination.
Impurities disrupt the orderly crystal lattice, requiring less thermal energy to melt and causing melting across a range of temperatures.
2
Analyze liquid boiling point behavior
Boiling point elevation at constant pressure signifies a non-volatile solute dissolved in the liquid.
Solute particles reduce the escaping tendency of liquid molecules into the vapor phase, requiring a higher temperature to match atmospheric pressure.
3
Evaluate chromatographic criteria
A pure substance contains only one chemical species and produces a single chromatogram spot.
If multiple components were present, differing partition coefficients would separate them into multiple spots.

Key Concept

Criteria of Purity for Substances
Question 2347Question →

Match each carbon species or bond descriptor on the left with its corresponding hybridization state, geometric configuration, or orbital overlap mode on the right.

Click a left item, then click its matching right item

Items

Central carbon in methane (CH4\text{CH}_4)
Carbon-carbon double bond π\pi component
Central carbon in carbon dioxide (CO2\text{CO}_2)
Carbon atom in ethene (C2H4\text{C}_2\text{H}_4)

Matches

Show answer & explanation

Answer

The central carbon in methane matches sp3sp^3 hybridization with tetrahedral geometry (109.5∘109.5^\circ); the π\pi bond component matches sideways overlap of unhybridized pp orbitals; the central carbon in carbon dioxide matches spsp hybridization with linear geometry (180∘180^\circ); and the carbon in ethene matches sp2sp^2 hybridization with trigonal planar geometry (120∘120^\circ).
Each carbon atom's hybridization and spatial arrangement depend directly on its steric number (number of σ\sigma bonds). Methane features four σ\sigma bonds (sp3sp^3, 109.5∘109.5^\circ tetrahedral). Ethene features three σ\sigma bonds per carbon (sp2sp^2, 120∘120^\circ trigonal planar). Carbon dioxide features two σ\sigma bonds (spsp, 180∘180^\circ linear). Π\Pi bonds are characterized by the sideways overlap of unhybridized 2p2p atomic orbitals.

Step-by-Step Solution

1
Determine the steric number and geometry of the carbon in methane (CH4\text{CH}_4).
Four single σ\sigma bonds give a steric number of 4, which dictates sp3sp^3 hybridization and a tetrahedral angle of 109.5∘109.5^\circ.
Mixing one ss and three pp orbitals forms four equivalent sp3sp^3 hybrid orbitals pointing to tetrahedral corners.
2
Identify how a carbon-carbon π\pi bond is formed.
It forms via lateral/sideways overlap of parallel, unhybridized pp orbitals above and below the internuclear axis.
Head-on overlap forms σ\sigma bonds, whereas parallel side-by-side overlap creates π\pi electron clouds.
3
Analyze the steric environment around the carbon in carbon dioxide (CO2\text{CO}_2).
The carbon forms two σ\sigma bonds (one to each oxygen atom) and two π\pi bonds, yielding a steric number of 2, corresponding to spsp hybridization and 180∘180^\circ linear geometry.
Two hybrid orbitals position themselves as far apart as possible at 180∘180^\circ.
4
Determine the hybridization and bond angles of carbon in ethene (C2H4\text{C}_2\text{H}_4).
Each carbon atom forms three σ\sigma bonds (steric number 3), requiring sp2sp^2 hybridization with a trigonal planar shape and 120∘120^\circ bond angles.
Three hybrid orbitals lie in a single plane separated by 120∘120^\circ.

Key Concept

Carbon Hybridization, Geometry, and Orbital Overlap
Question 2348Question →

Match each chemical transformation or physical process on the left with its correct thermodynamic energy classification and enthalpy description on the right.

Click a left item, then click its matching right item

Items

Dissolution of concentrated sulfuric acid (H2SO4\text{H}_2\text{SO}_4) in water
Thermal decomposition of calcium carbonate (CaCO3\text{CaCO}_3)
Photosynthesis in green plants
Complete combustion of ethanol (C2H5OH\text{C}_2\text{H}_5\text{OH})

Matches

Show answer & explanation

Answer

Sulfuric acid dissolution matches Exothermic with heat evolved; Calcium carbonate thermal decomposition matches Endothermic with thermal energy absorbed; Photosynthesis matches Endothermic with light energy absorbed; Ethanol combustion matches Exothermic with product bond formation releasing excess energy.
Each process is correctly linked to its thermodynamic behavior: acid dissolution and ethanol combustion release heat to surroundings (exothermic), while carbonate thermal decomposition and photosynthesis require net absorption of external energy (endothermic).

Step-by-Step Solution

1
Classify processes that release heat to the environment
The dissolution of concentrated acid and the combustion of ethanol raise the temperature of their surroundings, identifying them as exothermic reactions with negative enthalpy changes (ΔH<0\Delta H < 0).
Exothermic changes transfer thermal energy outward from the system.
2
Classify processes that require continuous energy absorption
The thermal breakdown of limestone and photosynthesis take in thermal or radiant energy from the outside, classifying them as endothermic reactions with positive enthalpy changes (ΔH>0\Delta H > 0).
Endothermic processes require net energy input to proceed.

Key Concept

Distinction between exothermic (ΔH<0\Delta H < 0, energy released) and endothermic (ΔH>0\Delta H > 0, energy absorbed) processes in physical and chemical systems.
Estimated Time:1m 30s
Question 2349Question →

Match each chemical reaction or treatment involving an acid or base on the left with its corresponding characteristic observation or underlying chemical property on the right.

Click a left item, then click its matching right item

Items

Warming ammonium chloride (NH4ClNH_4Cl) solid with aqueous sodium hydroxide (NaOHNaOH)
Heating solid sodium chloride (NaClNaCl) with concentrated tetraoxosulfate(VI) acid (H2SO4H_2SO_4)
Adding excess aqueous sodium hydroxide (NaOHNaOH) to a precipitate of zinc hydroxide (Zn(OH)2Zn(OH)_2)
Reacting copper turnings (CuCu) with concentrated trioxonitrate(V) acid (HNO3HNO_3)

Matches

Show answer & explanation

Answer

Warming NH4ClNH_4Cl with NaOHNaOH liberates NH3NH_3 gas which turns moist red litmus blue; heating NaClNaCl with concentrated H2SO4H_2SO_4 liberates HClHCl gas which forms white fumes with ammonia vapor; adding excess NaOHNaOH to Zn(OH)2Zn(OH)_2 dissolves the precipitate due to its amphoteric nature; reacting copper with concentrated HNO3HNO_3 yields brown NO2NO_2 gas due to the acid's strong oxidizing power.
Each pair correctly matches the specific acid/base transformation to its corresponding property: liberation of alkaline NH3NH_3 gas from ammonium salt displacement, liberation of volatile HClHCl gas by non-volatile H2SO4H_2SO_4, dissolution of amphoteric Zn(OH)2Zn(OH)_2 in excess base, and evolution of NO2NO_2 gas due to the oxidizing nature of concentrated HNO3HNO_3.

Step-by-Step Solution

1
Examine the reaction between ammonium chloride (NH4ClNH_4Cl) and sodium hydroxide (NaOHNaOH).
Heating ammonium salts with soluble alkalis yields sodium chloride, water, and ammonia gas (NH3NH_3), which is alkaline and turns red litmus blue.
This demonstrates the general chemical property of alkalis reacting with ammonium salts to displace volatile ammonia.
2
Examine the reaction between solid sodium chloride (NaClNaCl) and concentrated tetraoxosulfate(VI) acid (H2SO4H_2SO_4).
Concentrated H2SO4H_2SO_4 displaces hydrogen chloride (HClHCl) gas because H2SO4H_2SO_4 is significantly less volatile (higher boiling point) than HClHCl.
This illustrates the principle that non-volatile acids displace volatile acids from their salts.
3
Examine the effect of adding excess sodium hydroxide (NaOHNaOH) to zinc hydroxide (Zn(OH)2Zn(OH)_2).
The insoluble precipitate dissolves to form a clear solution containing the soluble complex anion [Zn(OH)4]2−[Zn(OH)_4]^{2-}.
This exhibits the amphoteric property of zinc hydroxide, allowing it to react with strong bases.
4
Examine the reaction of copper metal (CuCu) with concentrated trioxonitrate(V) acid (HNO3HNO_3).
Copper is oxidized to Cu2+Cu^{2+} while HNO3HNO_3 is reduced to brown nitrogen(IV) oxide gas (NO2NO_2), rather than evolving hydrogen gas.
This highlights that HNO3HNO_3 functions primarily as an oxidizing agent when reacting with metals below hydrogen in the reactivity series.

Key Concept

Distinct physical and chemical properties of acids and bases, including acid/base displacement volatility, amphoterism, and oxidizing acid behavior.
Question 2350Question →

Match each electromagnetic rule or concept in Column I with its corresponding physical description or application in Column II.

Click a left item, then click its matching right item

Items

Fleming's Left-Hand Rule
Right-Hand Grip Rule
Formula F=qvBsin⁡θF = qvB\sin\theta

Matches

Show answer & explanation

Answer

Fleming's Left-Hand Rule matches with determining the direction of magnetic force on a current-carrying conductor; Right-Hand Grip Rule matches with determining the direction of the magnetic field around a straight wire; F=qvBsin⁡θF = qvB\sin\theta matches with calculating the magnitude of magnetic force on a moving electric charge.
Fleming's Left-Hand Rule establishes the perpendicular direction of magnetic force relative to current and magnetic field vectors. The Right-Hand Grip Rule relates linear current direction to circular magnetic field lines. The equation F=qvBsin⁡θF = qvB\sin\theta directly calculates the magnitude of force on a free charge moving through a uniform magnetic field.

Step-by-Step Solution

1
Analyze Fleming's Left-Hand Rule.
The thumb, forefinger, and middle finger represent Force, Magnetic Field, and Current respectively.
It predicts the direction of mechanical motion/force produced in motors and conductors.
2
Analyze the Right-Hand Grip Rule.
Pointing the right thumb in the current's direction makes the curled fingers show the magnetic field line direction.
It provides a simple geometric method to determine field orientation around conductors.
3
Analyze the force relation F=qvBsin⁡θF = qvB\sin\theta.
It quantifies the Lorentz force acting on an isolated moving electric charge.
The magnetic force magnitude depends on charge, velocity, magnetic field strength, and the angle between velocity and field.

Key Concept

Fundamental rules and formulas of electromagnetism
Question 2351Question →

Match each optical instrument component or device on the left with its correct focal length requirement and image formation condition on the right.

Click a left item, then click its matching right item

Items

Compound Microscope Objective Lens
Astronomical Telescope Objective Lens
Simple Magnifying Glass
Slide / Film Projector Lens

Matches

Show answer & explanation

Answer

Compound Microscope Objective Lens pairs with very short focal length producing a real, inverted, and magnified intermediate image. Astronomical Telescope Objective Lens pairs with long focal length forming a real, inverted, and diminished image of a distant body. Simple Magnifying Glass pairs with single convex lens with object placed within focal length producing an erect, virtual, and magnified image. Slide / Film Projector Lens pairs with convex lens with object positioned between f and 2f producing a real, inverted, and enlarged image on a screen.
The matching correct pairs align each optical device with its precise optical parameter: microscope objectives utilize short focal lengths for high magnification of near objects, telescope objectives utilize long focal lengths for distant objects, simple magnifiers place objects closer than the focal point to form virtual erect images, and projectors place objects between one and two focal lengths to cast real enlarged images on a screen.

Step-by-Step Solution

1
Analyze the objective lens of a compound microscope
It requires a very short focal length to achieve high linear magnification of near objects.
The specimen is placed just outside the focal point (f<u<2ff < u < 2f), producing a real, inverted, magnified image inside the tube.
2
Analyze the objective lens of an astronomical telescope
It requires a long focal length and large aperture.
Distant celestial bodies subtend tiny angles at the eye; a long focal length objective creates a larger real intermediate image for the eyepiece to magnify.
3
Analyze the ray path condition of a simple magnifying glass
The object is held within the principal focus (u<fu < f).
Light rays emerging from the lens diverge, forming an enlarged, virtual, and erect image on the same side of the lens as the object.
4
Analyze the image projection setup in a slide projector
The slide is placed between ff and 2f2f of a converging lens.
According to the thin lens formula, placing an object between ff and 2f2f yields a real, inverted, magnified image beyond 2f2f.

Key Concept

Operating principles and ray placement parameters of optical instruments
Question 2352Question →

Match each phenotypic trait or population distribution profile on the left with its corresponding characteristic pattern of variation or graphical feature on the right.

Click a left item, then click its matching right item

Items

Human height and skin color
ABO blood group and tongue rolling ability
Bell-shaped frequency curve
Discrete bar chart with clear gaps

Matches

Show answer & explanation

Answer

Human height and skin color matches with Continuous variation influenced by polygenes and environmental factors. ABO blood group and tongue rolling ability matches with Discontinuous variation controlled by monogenic inheritance with minimal environmental effect. Bell-shaped frequency curve matches with Graphical representation showing a continuous spectrum of intermediate phenotypes. Discrete bar chart with clear gaps matches with Graphical representation showing non-overlapping, distinct phenotypic categories.
Human height and skin color exhibit continuous variation caused by polygenic inheritance and environmental influences. ABO blood group and tongue rolling ability show discontinuous variation controlled by single genes with minimal environmental impact. Population data for continuous variation forms a smooth bell-shaped curve showing intermediate phenotypes, whereas discontinuous variation forms a discrete bar chart with distinct non-overlapping categories.

Step-by-Step Solution

1
Identify the biological nature and genetic control of phenotypic traits
Human height and skin color exhibit gradual transitions (polygenic continuous variation), while ABO blood group and tongue rolling show clear, separate phenotypic classes (monogenic discontinuous variation).
Continuous traits show a continuum of phenotypes due to multiple genes, whereas discontinuous traits show distinct classes due to single-gene control.
2
Analyze the graphical representations associated with population data for both variation types
Continuous data produces a smooth, bell-shaped normal distribution curve, while discontinuous data forms separate bars representing distinct non-overlapping categories.
Quantitative measurements across a spectrum form a continuous curve, while qualitative discrete categories plot as separate bars.
3
Pair each left item with its corresponding genetic mechanism or graphical characteristic
All four pairs are correctly matched based on variation patterns and graphical profiles.
Ensures complete concept alignment across examples, mechanisms, and graphical representations.

Key Concept

Distinction between continuous and discontinuous variation in inheritance patterns, underlying genetic mechanisms, and graphical representations.
Question 2353Question →

Match each industrial chemical listed on the left with its appropriate chemical category and operational production characteristic on the right.

Click a left item, then click its matching right item

Items

Tetraoxosulfate(VI) acid (H2SO4H_2SO_4)
Paracetamol (Acetaminophen)
Sodium hydroxide (NaOHNaOH)
Analytical grade Silver Nitrate (AgNO3AgNO_3)

Matches

Show answer & explanation

Answer

Tetraoxosulfate(VI) acid matches heavy chemical produced continuously in massive tonnage; Paracetamol matches fine chemical produced in small batches for pharmaceutical applications; Sodium hydroxide matches heavy chemical synthesized on a large scale as a basic alkali raw material; Analytical grade Silver Nitrate matches fine chemical manufactured in limited quantities with strict purity for laboratory testing.
Heavy chemicals like Tetraoxosulfate(VI) acid and Sodium hydroxide are manufactured on a massive industrial scale through continuous production processes. They serve as fundamental raw materials for other industries and have low to moderate unit costs. Fine chemicals like Paracetamol and Analytical grade Silver Nitrate are produced in small batch quantities, possess high chemical purity standards, command high unit prices, and serve specialized applications such as medicine and scientific research.

Step-by-Step Solution

1
Analyze Tetraoxosulfate(VI) acid (H2SO4H_2SO_4)
H2SO4H_2SO_4 is manufactured worldwide in millions of tonnes via the Contact process. It is a classic heavy chemical with a relatively low cost per unit mass used broadly across chemical manufacturing.
Heavy chemicals are characterized by high volume, continuous production, and widespread raw material utility.
2
Analyze Paracetamol
Paracetamol is a pharmaceutical drug prepared in small, carefully monitored batch processes to guarantee high chemical purity and safety for human consumption.
Pharmaceuticals are classified as fine chemicals due to their high unit value, precise batch manufacturing, and high degree of purity.
3
Analyze Sodium hydroxide (NaOHNaOH)
Sodium hydroxide is produced in vast amounts alongside chlorine gas in the chlor-alkali process, functioning as a primary basic heavy alkali.
Large-scale industrial bases and alkalis produced for general industrial operations are heavy chemicals.
4
Analyze Analytical grade Silver Nitrate (AgNO3AgNO_3)
Analytical reagents are synthesized in small amounts with strict quality specifications (>99.9%>99.9\% purity) for qualitative and quantitative laboratory procedures.
Specialty laboratory reagents sold in high-cost, small-quantity containers fall under fine chemicals.

Key Concept

Classification and operational properties of Heavy Chemicals vs Fine Chemicals
Question 2354Question →

Match each chemical process on the left with the correct classical or modern redox concept on the right that specifically describes the change taking place.

Click a left item, then click its matching right item

Items

Removal of oxygen from ZnO(s)\text{ZnO(s)} to yield Zn(s)\text{Zn(s)} in the reaction ZnO+C→Zn+CO\text{ZnO} + \text{C} \rightarrow \text{Zn} + \text{CO}
Addition of oxygen to carbon to form carbon monoxide in ZnO+C→Zn+CO\text{ZnO} + \text{C} \rightarrow \text{Zn} + \text{CO}
Loss of electrons by sodium atoms to form Na+\text{Na}^+ in 2Na+Cl2→2NaCl2\text{Na} + \text{Cl}_2 \rightarrow 2\text{NaCl}
Decrease in oxidation state of nitrogen from 00 in N2\text{N}_2 to −3-3 in NH3\text{NH}_3

Matches

Show answer & explanation

Answer

Removal of oxygen from zinc oxide corresponds to classical reduction; addition of oxygen to carbon corresponds to classical oxidation; loss of electrons by sodium corresponds to modern electron-transfer oxidation; and the decrease in oxidation number of nitrogen corresponds to modern oxidation number reduction.
Each chemical transformation is matched according to whether it describes classical oxygen transfer or modern electron/oxidation state changes. Removal of oxygen represents classical reduction; addition of oxygen represents classical oxidation; loss of electrons represents modern electronic oxidation; and a decrease in oxidation number represents modern reduction.

Step-by-Step Solution

1
Analyze classical definitions of redox
Classical oxidation involves the addition of oxygen or removal of hydrogen, while classical reduction involves the removal of oxygen or addition of hydrogen.
This establishes the ground rules for the first two pairs.
2
Analyze modern electronic and oxidation number definitions
Modern oxidation is the loss of electrons (OIL) or an increase in oxidation state. Modern reduction is the gain of electrons (RIG) or a decrease in oxidation state.
This establishes the ground rules for the remaining two pairs.
3
Match each process to its corresponding definition
Zinc oxide losing oxygen is classical reduction. Carbon gaining oxygen is classical oxidation. Sodium losing electrons is modern electronic oxidation. Nitrogen decreasing in oxidation number from 0 to -3 is modern oxidation number reduction.
Applying the concepts directly aligns each process with its primary redox definition.

Key Concept

Classical vs Modern Concepts of Redox Reactions
Question 2355Question →

Match each ecological sampling instrument or technique with its most appropriate sampling application in field biology studies.

Click a left item, then click its matching right item

Items

Pooter
Pitfall trap
Quadrat frame
Line transect

Matches

Show answer & explanation

Answer

Pooter pairs with collecting tiny insects via suction; Pitfall trap pairs with capturing crawling arthropods on the ground; Quadrat frame pairs with estimating population density of stationary plants; Line transect pairs with determining species distribution along an environmental gradient.
Each instrument maps directly to its specific field biological function: the pooter uses suction for fragile insects, the pitfall trap captures soil-crawling fauna in a sunken container, the quadrat isolates standard areas for non-motile population counts, and the line transect continuously tracks species shifts across environmental gradients.

Step-by-Step Solution

1
Analyze the functional mechanism of each instrument
Pooter uses suction for delicate leaf insects; Pitfall traps catch ground-level crawling species.
Apparatus design dictates which organism group can be effectively sampled.
2
Differentiate spatial area sampling from gradient transition sampling
Quadrat frames define standard area bounds for non-mobile species, whereas line transects map linear changes across gradients.
Quadrats yield area-based density measurements, while transects capture ecological zonation.

Key Concept

Ecological Sampling Instruments and Techniques
Question 2356Question →

In the classification of Spermatophytes, gymnosperms and angiosperms display distinct anatomical and reproductive features. Match each diagnostic feature listed on the left with its corresponding plant group on the right.

Click a left item, then click its matching right item

Items

Ovules borne uncovered on megasporophyll scales without an enclosing ovary wall
Double fertilization yielding a diploid zygote (2n2n) and a triploid endosperm (3n3n)
Embryo with a single seed leaf, leaves with parallel venation, and floral parts in multiples of three
Embryo with two seed leaves, leaves with net-like (reticulate) venation, and a taproot system

Matches

Show answer & explanation

Answer

Uncovered ovules match Gymnospermae; Double fertilization yielding triploid endosperm matches Angiospermae; Single cotyledon with parallel venation matches Monocotyledoneae; Two cotyledons with reticulate venation match Dicotyledoneae.
The correct pairings accurately reflect the defining evolutionary and structural traits of Spermatophytes: uncovered ovules on megasporophyll scales are characteristic of Gymnospermae; double fertilization producing triploid (3n3n) endosperm defines Angiospermae; single cotyledons paired with parallel leaf venation characterize Monocotyledoneae; and two cotyledons paired with reticulate leaf venation characterize Dicotyledoneae.

Step-by-Step Solution

1
Identify the primary seed enclosure characteristic
Unenclosed (naked) ovules on megasporophylls define Gymnospermae.
Gymnosperms lack an ovary wall surrounding their ovules.
2
Identify the reproductive fertilization hallmark of flowering plants
Double fertilization yielding a triploid (3n3n) nutritive tissue defines Angiospermae.
Angiosperms undergo a secondary fertilization event where one sperm fuses with two polar nuclei.
3
Distinguish between the two main classes of angiosperms
Single cotyledon with parallel leaf venation corresponds to Monocotyledoneae, while two cotyledons with reticulate venation correspond to Dicotyledoneae.
Morphological traits such as cotyledon count, leaf venation, and root system architecture divide angiosperms into monocots and dicots.

Key Concept

Diagnostic reproductive and structural distinctions between Gymnosperms, Angiosperms, Monocotyledons, and Dicotyledons
Estimated Time:1m 30s
Question 2357Question →

Match each seral stage of hydrarch succession (hydrosere) in a freshwater habitat on the left with its corresponding characteristic vegetation or ecological role on the right.

Click a left item, then click its matching right item

Items

Phytoplankton stage
Submerged macrophyte stage
Floating macrophyte stage
Reed-swamp stage

Matches

Show answer & explanation

Answer

Phytoplankton stage pairs with microscopic algae; Submerged macrophyte stage pairs with rooted aquatic plants like Vallisneria; Floating macrophyte stage pairs with broad surface-leaved plants like Nymphaea; Reed-swamp stage pairs with emergent amphibious plants like Typha.
In hydrarch primary succession, microscopic phytoplankton act as pioneers in deep water. As organic debris accumulates on the bed, submerged plants establish, followed by floating-leaved species that block sunlight, and finally emergent reed-swamp plants that convert shallow waters into wet soil.

Step-by-Step Solution

1
Identify the pioneer community of a hydrosere.
The pioneer stage consists of unattached microscopic producers (phytoplankton) that start organic sedimentation.
Deep open water bodies lack soil anchorages for rooted plants initially.
2
Trace the sequence of rooted vegetation growth as water depth decreases.
Fully submerged rooted species grow first, followed by floating-leaved species as mud layers thicken, and finally emergent amphibious reeds near the water edges.
Each community alters light penetration and substrate depth, facilitating the establishment of the next seral stage.

Key Concept

Hydrarch succession stages (hydrosere)
Question 2358Question →

Match each human regulatory hormone listed on the left with its corresponding physiological action or target mechanism on the right.

Click a left item, then click its matching right item

Items

Parathormone (PTH)
Aldosterone
Oxytocin
Calcitonin

Matches

Show answer & explanation

Answer

Parathormone matches with increasing plasma calcium levels via bone resorption; Aldosterone matches with stimulating sodium ion reabsorption in kidney tubules; Oxytocin matches with inducing uterine contraction and milk ejection; Calcitonin matches with promoting calcium deposition into bone matrix.
Each hormone is correctly matched according to its endocrine target and action: Parathormone elevates plasma calcium concentration, Aldosterone increases renal sodium reabsorption, Oxytocin induces uterine contractions and milk let-down, and Calcitonin lowers plasma calcium concentration by depositing calcium into bone.

Step-by-Step Solution

1
Determine the physiological action of Parathormone (PTH)
PTH raises plasma Ca2+Ca^{2+} levels by activating bone breakdown (resorption) and decreasing calcium excretion.
Parathyroid hormone regulates calcium homeostasis by preventing hypocalcemia.
2
Determine the function of Aldosterone
Aldosterone targets distal convoluted tubules and collecting ducts to reabsorb Na+Na^+.
As a principal mineralocorticoid, it regulates electrolyte balance and blood pressure.
3
Analyze the action of Oxytocin
Oxytocin acts on target reproductive smooth muscle tissues during parturition and lactation.
It directly triggers uterine contractions and the milk ejection reflex.
4
Identify the function of Calcitonin
Calcitonin works antagonistically to PTH by depositing excess blood Ca2+Ca^{2+} into bone tissue.
Thyroid C-cells release calcitonin to prevent hypercalcemia.

Key Concept

Endocrine regulation and physiological mechanisms of human hormones
Question 2359Question →

Match each sodium compound listed on the left with its corresponding characteristic property, industrial preparation process, or commercial application on the right.

Click a left item, then click its matching right item

Items

Sodium peroxide (Na2O2\text{Na}_2\text{O}_2)
Sodium hydroxide (NaOH\text{NaOH})
Sodium hydrogentrioxocarbonate(IV) (NaHCO3\text{NaHCO}_3)
Sodium trioxocarbonate(IV) decahydrate (Na2CO3⋅10H2O\text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O})

Matches

Show answer & explanation

Answer

Sodium peroxide matches with acting as an oxygen generator in breathing apparatus; Sodium hydroxide matches with industrial manufacture via brine electrolysis in a mercury cathode cell; Sodium hydrogentrioxocarbonate(IV) matches with thermal decomposition releasing carbon dioxide gas; Sodium trioxocarbonate(IV) decahydrate matches with efflorescence in dry atmosphere to form a monohydrate powder.
Each sodium compound is paired correctly according to its fundamental chemical behavior or industrial utility: Sodium peroxide reacts with carbon dioxide to regenerate oxygen; Sodium hydroxide is manufactured via the chlor-alkali process in Castner-Kellner mercury cells; Sodium hydrogentrioxocarbonate(IV) undergoes thermal decomposition to release carbon dioxide; and Sodium trioxocarbonate(IV) decahydrate loses hydration water through efflorescence.

Step-by-Step Solution

1
Analyze the chemical property and application of sodium peroxide (Na2O2\text{Na}_2\text{O}_2).
Sodium peroxide reacts with carbon dioxide according to the equation 2Na2O2+2CO2→2Na2CO3+O22\text{Na}_2\text{O}_2 + 2\text{CO}_2 \rightarrow 2\text{Na}_2\text{CO}_3 + \text{O}_2, releasing oxygen gas.
This property makes it effective as an oxygen rebreather component.
2
Identify the industrial preparation method for sodium hydroxide (NaOH\text{NaOH}).
Sodium hydroxide is produced by electrolyzing concentrated brine (NaCl(aq)\text{NaCl}_{(aq)}) in a Castner-Kellner cell containing a mercury cathode.
Sodium ions discharge at the mercury cathode forming an amalgam, which reacts with water to yield pure NaOH\text{NaOH}.
3
Examine the thermal stability of sodium hydrogentrioxocarbonate(IV) (NaHCO3\text{NaHCO}_3).
Heating NaHCO3\text{NaHCO}_3 causes decomposition: 2NaHCO3→ΔNa2CO3+H2O+CO22\text{NaHCO}_3 \xrightarrow{\Delta} \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} + \text{CO}_2.
Alkali metal hydrogentrioxocarbonates decompose upon gentle heating to liberate carbon dioxide gas.
4
Determine the effect of air exposure on hydrated sodium trioxocarbonate(IV) (Na2CO3⋅10H2O\text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O}).
Exposure to dry air leads to the loss of nine water molecules: Na2CO3⋅10H2O→Na2CO3⋅H2O+9H2O\text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O} \rightarrow \text{Na}_2\text{CO}_3\cdot \text{H}_2\text{O} + 9\text{H}_2\text{O}.
This spontaneous loss of water of crystallization to the atmosphere is termed efflorescence.

Key Concept

Properties, Preparation, and Uses of Major Sodium Compounds
Question 2360Question →

Match each classical trade theory or economic principle on the left with its corresponding foundational premise or proponent on the right.

Click a left item, then click its matching right item

Items

Absolute Advantage Theory
Comparative Advantage Theory
Opportunity Cost Theory of Trade
Limits to Terms of Trade

Matches

Show answer & explanation

Answer

Absolute Advantage Theory matches Adam Smith's absolute labor cost approach; Comparative Advantage Theory matches David Ricardo's relative opportunity cost model; Opportunity Cost Theory of Trade matches Gottfried Haberler's production possibility curve framework; Limits to Terms of Trade matches the domestic cost ratios boundary.
Each theory is paired correctly with its originator or core economic premise: Adam Smith established absolute advantage based on absolute cost efficiency; David Ricardo formulated comparative advantage based on relative cost ratios; Gottfried Haberler introduced the opportunity cost curve model; and the limits to the terms of trade are set by internal opportunity cost ratios.

Step-by-Step Solution

1
Identify the proponent and core assumption of Absolute Advantage.
Adam Smith proposed that countries should specialize in goods where they possess absolute labor cost advantages.
This establishes the historical origin of free trade theory.
2
Identify the proponent and core assumption of Comparative Advantage.
David Ricardo showed that mutual gains from trade occur whenever relative opportunity costs differ between nations.
This extends Smith's model to cases where one country is more efficient in all lines of production.
3
Identify Haberler's contribution to trade theory.
Gottfried Haberler reformulated comparative advantage using the opportunity cost concept derived from production possibility frontiers.
This removed the restrictive assumption of the labor theory of value.
4
Determine the condition for mutually beneficial terms of trade.
The terms of trade must fall between the domestic opportunity cost ratios of both trading countries.
If the exchange rate falls outside these bounds, at least one nation would experience a net loss from trade.

Key Concept

Foundational Theories of International Trade and Terms of Trade Limits
PreviousPage 118 / 130Next
All practice questions — JAMB UTME | Examkin