Science MCQs

Magnesium reacts with oxygen to form magnesium oxide.

Potassium chlorate decomposes to potassium chloride and oxygen gas.

Tarnishing is oxidation of metal surfaces like silver or copper.

Applying oil forms a protective layer that prevents contact with air and moisture.

Reactants are substances that participate in a chemical reaction.

Physical changes do not alter the chemical composition so the original substance can be recovered by simple physical means.

A chemical change involves a alteration in the chemical structure resulting in products with different properties.

Common signs include a change in temperature (heat absorbed or released) formation of bubbles (gas) or formation of a solid (precipitate).

Oxygen from the air is a key reactant in the chemical processes of combustion and rusting (oxidation).

Flammability is defined as the ability of a substance to burn or ignite.