When purifying untreated surface water in the field, technicians must first strain the liquid through a fine mesh filter to remove suspended sediment and large particulates. Once the water is visibly clear, a measured dose of sodium hypochlorite solution is added to neutralize microscopic pathogens. Before sealing the container for the required thirty-minute contact period, the operator must agitate the mixture thoroughly for thirty seconds to ensure even chemical dispersion. Finally, the container is uncapped and checked for a faint chlorine aroma before consumption is permitted.
According to the passage, which action must the operator take immediately prior to sealing the container for the contact period?
- AStrain the liquid through a fine mesh filter to eliminate particulates
- Agitate the mixture thoroughly for thirty secondsCevap
- CAllow the water to stand undisturbed for thirty minutes
- DCheck the uncapped container for a faint chlorine aroma
Cevap
Agitate the mixture thoroughly for thirty seconds
The text directly states that 'Before sealing the container for the required thirty-minute contact period, the operator must agitate the mixture thoroughly for thirty seconds.' Therefore, agitating the mixture is the exact action performed immediately prior to sealing.
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