Researchers investigated the hydrothermal growth of zinc oxide (\text{ZnO}) nanorods for u… — ACT

Researchers investigated the hydrothermal growth of zinc oxide ( $\text{ZnO}$ ) nanorods for use in piezoelectric nanogenerators. In five separate experimental trials, the reaction vessel temperature was set to $90^\circ\text{C}$ , $100^\circ\text{C}$ , $110^\circ\text{C}$ , $120^\circ\text{C}$ , and $130^\circ\text{C}$ , respectively. In all trials, the zinc nitrate precursor concentration was maintained at $0.05\text{ M}$ , the reaction duration was held at $4\text{ hours}$ , and the autoclave fill volume was kept at $100\text{ mL}$ . After each trial, the average aspect ratio (length-to-diameter ratio) of the synthesized nanorods was determined using scanning electron microscopy. Match each experimental component to its correct variable classification.

Reaction vessel temperature ( $90^\circ\text{C}$ to $130^\circ\text{C}$ )Independent Variable
Average aspect ratio of the synthesized nanorodsDependent Variable
Zinc nitrate precursor concentration ( $0.05\text{ M}$ ) and reaction duration ( $4\text{ hours}$ )Controlled Variable

Cevap

Reaction vessel temperature matches Independent Variable; Average aspect ratio of synthesized nanorods matches Dependent Variable; Precursor concentration and reaction duration match Controlled Variable.

In scientific experiments, the independent variable is the parameter deliberately manipulated (here, the reaction vessel temperature across five distinct values). The dependent variable is the observed outcome measured to test the hypothesis (here, the nanorod aspect ratio). Controlled variables are baseline parameters held constant across all conditions (here, precursor concentration and duration) to ensure a fair test.

Adım Adım Çözüm

Identify the factor explicitly varied by the experimenters across trials.

The reaction vessel temperature is systematically altered (

90^\circ\text{C}

130^\circ\text{C}

), identifying it as the independent variable.

The independent variable is the factor deliberately manipulated by the researcher.

Identify the outcome measured as a result of changing the independent variable.

The average aspect ratio of the nanorods is measured after each trial, identifying it as the dependent variable.

The dependent variable is the measured response or outcome affected by changes in the independent variable.

Identify the parameters maintained at constant values across all trials.

Precursor concentration (

0.05\text{ M}

) and reaction duration (

4\text{ hours}

) remain constant in every trial, identifying them as controlled variables.

Controlled variables are held constant to prevent extraneous factors from influencing the dependent variable.

Anahtar Kavram

Classification of variables in experimental design (independent, dependent, and controlled variables).

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