Test: Chemical & Chemical Changes - Class 7 MCQ

Sand is a mixture of different substances and not a pure chemical substance.

The chemical symbol for gold is Au, derived from the Latin word 'aurum'.

The correct chemical formula for water is H₂O, indicating two hydrogen atoms and one oxygen atom.

The chemical reaction between hydrochloric acid and sodium hydroxide produces salt and water.

Melting of ice is a physical change as it does not involve any chemical reaction.

Crystallization is the process of separating a solid from a liquid by evaporating the liquid and allowing the solid to crystallize.

Burning of wood is a chemical change as it involves a chemical reaction resulting in the formation of ash and gases.

The balanced chemical equation for the reaction between hydrogen and oxygen to form water is 2H₂ + O₂ → 2H₂O.

Silver nitrate is a chemical substance used in photography for developing film.

The chemical formula for table salt is NaCl, indicating one sodium atom and one chlorine atom.

Burning of gasoline is a chemical change as it involves a chemical reaction resulting in the release of energy and combustion products.

Decantation is the process of separating a solid from a liquid by pouring the liquid into another container.

Freezing of water is a physical change as it does not involve any chemical reaction.

The chemical symbol for carbon is C, derived from the Latin word 'carbo'.

Burning of a candle is a chemical change as it involves a chemical reaction resulting in the production of carbon dioxide and water vapor.

The balanced chemical equation for the reaction between sodium and chlorine to form table salt is 2Na + Cl₂ → 2NaCl.

Ammonium nitrate is a chemical substance used in fertilizer for providing nitrogen to plants.

The chemical formula for carbon dioxide is CO₂, indicating one carbon atom and two oxygen atoms.

Dissolving of salt in water is a physical change as it does not involve any chemical reaction.

Distillation is the process of separating a mixture of liquids with different boiling points by heating and condensing their vapors.