PMS Everyday Science MCQs

Paint forms a protective barrier.
This slows the electrochemical reactions that cause rust.

Corrosion involves chemical or electrochemical reactions.
Rusting is a common example involving iron.

Acids donate protons in chemical reactions.
In water, they increase hydrogen-ion concentration.

Bases accept protons according to Brønsted-Lowry theory.
Many aqueous bases produce hydroxide ions.

pH values below 7 indicate acidity.
A pH of 3 is distinctly acidic.

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.