Pakistan MCQs

Chlorine in controlled amounts disinfects water.
It reduces disease-causing bacteria and viruses.

Calcium and magnesium ions cause hardness.
Hard water forms scale and reduces soap lather.

Hardness ions react with soap molecules.
The insoluble products waste soap and reduce lather.

pH values above 7 indicate basicity.
A pH of 10 is alkaline.

Litmus changes color depending on acidity or basicity.
Red litmus turns blue in bases, while blue litmus turns red in acids.

Acid and base properties cancel during neutralization.
The products commonly include a salt and water.

Antacids contain mild bases.
They reduce acidity and relieve symptoms such as heartburn.

The stomach secretes hydrochloric acid.
It helps activate digestive enzymes and kill many microbes.

Vinegar contains dilute acetic acid.
This acid gives vinegar its sour taste and preservative effect.

Citrus fruits such as lemons and oranges contain citric acid.
It contributes to their sour taste.

Muscle cells can produce lactate during anaerobic metabolism.
This supports short-term energy production when oxygen delivery is limited.

Carbon dioxide does not support combustion and is nonconductive.
It can displace oxygen around a fire.