Question

(a) Arrange the following as per the instruction given in the brackets:
(i) He, Ar, Ne (Increasing order of the number of electron shells)
(ii) Na, Li, K (Increasing Ionisation Energy)
(iii) F, Cl, Br (Increasing electronegativity)
(iv) Na, K, Li (Increasing atomic size)
[4]

b) State the type of Bonding in the following molecules:
(i) Water
(ii) Calcium oxide
[2]

(c) Answer the following questions:
(i) How will you distinguish between Ammonium hydroxide and Sodium hydroxide using copper sulphate solution?
(ii) How will you distinguish between dilute hydrochloric acid and dilute sulphuric acid using lead nitrate solution?
[2]

(d) Identify the salts P and Q from the observations given below:
(i) On performing the flame test salt P produces a lilac coloured flame and its solution gives a white precipitate with silver nitrate solution, which is soluble in Ammonium hydroxide solution.
(ii) When dilute HCl is added to a salt Q, a brisk effervescence is produced and the gas turns lime water milky. When $N{H}_{4}OH$ solution is added to the above mixture (after adding dilute HCl), it produces a white precipitate which is soluble in excess $N{H}_{4}OH$ solution.
[2]

Answer 1

(a) (i) \( He , Ne , Ar \) (ii) \( K , Na , Li \) (iii) \( Br , Cl , F \) (iv) \( Li , Na , K \) (b) (i) Covalent bond (ii) Ionic or electrovalent bond (c) (i) On adding copper sulphate solution to both, the one that forms a blue precipitate that is insoluble in excess of the reagent is \( NaOH \). The other solution forms a pale blue precipitate that dissolves in excess reagent to form an ink blue solution and this is \( NH _{4} OH \). (ii) On adding lead nitrate solution to both, they form white precipitate but the one in which the white precipitate disappears on heating is \( HCl \), while in \( H _{2} SO _{4} \), the white precipitate remains insoluble on heating. (d) (i) \( KCl \) or potassium chloride (ii) \( ZnCO _{3} \) or Zinc carbonate