Read the following and answer any four questions from 2(i) to 2(v).
A compound, X of sodium forms a white powder. It is a constituent of baking powder and is used in some antacids. When heated it gives a compound, Y which is anhydrous and absorbs water to become a hydrated salt. When this salt is kept in open air, it loses water molecules in a process called efflorescence. When dissolved in water it forms a strong base and a weak acid, Z.
(i) What is the compound, X?
(a) NaHCO
(b) Na₂CO
(c) NOH
(d) NaCl
(ii) The compound, Y is
(a) NaHCO,
(b) Na₂CO,
(c) Na₂CO, 10H₂0
(d) NaCl
(iii) What is the nature of the solution formed by dissolving Y in water?
(a) Alkaline
(b) Acidic
(c) Neutral
(d) It remains insoluble.
(iv) Identify the compound, Z.
(a) CO₂
(b) H₂CO,
(C) NaOH
(d) H₂O
(v) Sodium carbonate is a basic compound because it is a salt of a
(a) strong acid and strong base
(b) weak acid and weak base
(c) strong acid and weak base
(d) weak acid and strong base.
Answers
(i) (a) Compound X is Sodium Hydrogen Carbonate (NaHCO)
(ii) (b) Compound Y is Anhydrous Sodium Carbonite Na2CO
(iii) (a) Alkaline
(iv) (b) Compound Z is Carbonic Acid H2CO.
(v) (d) weak acid and strong base.
Answers are as follows -
(i) What is the compound, X?
(a) NaHCO3
It is known by the name sodium hydrogen carbonate, baking soda, sodium bicarbonate.
(ii) The compound, Y is
(c) Na₂CO3.10H₂O
Compound Y is known by the name sodium carbonate decahydrate.
(iii) What is the nature of the solution formed by dissolving Y in water?
(a) Alkaline
Due to presence of hydroxyl ions
(iv) Identify the compound, Z.
(b) H₂CO3
It is a weak acid formed along with strong base sodium hydroxide.
(v) Sodium carbonate is a basic compound because it is a salt of a
(d) weak acid and strong base
Presence of strong base makes the solution basic.