The reason for using Aluminium in the alloy duralumin is:

1. Aluminium is brittle.
2. Aluminium gives strength.
3. Aluminium brings lightness.
4. Aluminium lowers melting point.

The drying agent used to dry HCl gas is:

1. Conc. H₂SO₄
2. ZnO
3. Al₂O₃
4. CaO

Fill in the blanks with the choices given in brackets:

(i) Conversion of ethanol to ethene by the action of concentrated sulphuric acid is an example of …………… (dehydration/dehydrogenation/dehydrohalogenation)

(ii) When sodium chloride is heated with concentrated sulphuric acid below 200°C, one of the products formed is …………… (sodium hydrogen sulphate / sodium sulphate / chlorine)

(iii) Ammonia reacts with excess chlorine to form …………… (nitrogen / nitrogen trichloride / ammonium chloride)

(iv) Substitution reactions are characteristic reactions of …………… (alkynes / alkenes / alkanes)

(v) In Period 3, the most metallic element is …………… (sodium / magnesium / aluminium)

Write a balanced chemical equation for each of the following reactions:

(i) Reduction of copper (II) oxide by hydrogen.

(ii) Action of dilute sulphuric acid on sodium hydroxide.

(iii) Action of dilute sulphuric acid on zinc sulphide.

(iv) Ammonium hydroxide is added to ferrous sulphate solution.

(v) Chlorine gas is reacted with ethene.