State which of the following pertain to - chemical changes.

(a) Substance retains its identity.

(b) The change is permanent.

(c) No new substance is formed.

(d) Is easily reversible.

(e) Produces one or more new substances by change in its composition.

(f) The change is temporary.

(g) The composition and properties of the original substance are not altered.

Give four reasons why burning of a magnesium ribbon in air is considered a chemical change.

Is change of state of matter - a physical or a chemical change. Give reasons.

State which of the following terms connected with change of state of matter i.e.

(a) Melting

(b) Vaporisation

(c) Condensation

(d) Freezing

pertain to

(i) Conversion of a liquid into a vapour or gas.

(ii) Conversion of a liquid into a solid.

(iii) Conversion of a solid into a liquid on heating.