When ammonium chloride is dissolved in water in a test tube, the tube feels colder showing that

Zinc displaces copper from an aqueous solution of copper (ll) salt because

The alloy used for metal work and plumbing contains

Classify each of the following as physical change or a chemical change:

(a) fractional distillation of liquefied air;

(b) cracking of petroleum fractions;

(c) conversion of rhombic sulphur to monoclinic sulphur;

(d) chromatographic separation of chlorophyll.

(a) Give one disadvantage of:

(i) hard water

(ii) soft water

(b) Explain why the degree of hardness in a sample of clear lime water is higher than in another sample has that been turned milky by carbon (IV) oxide.