Washing soda (Na₂CO₃.10H₂O)

When sodium hydrogen carbonate is heated then sodium carbonate and water is formed along with the evolution of carbon dioxide gas.

A solution turns red litmus blue, its pH is likely to be
(a) 1
(b) 4
(c) 5
(d) 10
Answer (d) 10

A solution reacts with crushed egg-shells to give a gas that turns lime-water milky. The solution contains
(a) NaCl
(b) HCl
(c) LiCl
(d) KCl

Answer (b) HCl

10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HCl. If we take 20 mL of the same solution of NaOH, the amount of HCl solution (the same solution as before) required to neutralise it will be
(a) 4 mL
(b) 8mL
(c) 12 mL
(d) 16 mL

Answer (d) 16 mL

Which one of the following types of medicines is used for treating indigestion?
(a) Antibiotic
(b) Analgesic
(c) Antacid
(d) Antiseptic

Answer (c) Antacid

 Write word equations and then balanced equations for the reaction taking place when −
(a) dilute sulphuric acid reacts with zinc granules.
(b) dilute hydrochloric acid reacts with magnesium ribbon.
(c) dilute sulphuric acid reacts with aluminium powder.
(d) dilute hydrochloric acid reacts with iron filings.

Answer

(a) H₂SO₄ (aq) + Zn (s) → ZnSO₄ (aq) + H₂ (g)

(b) 2HCl (aq) + Mg (s) → MgCl (aq) + H₂ (g)

(c) 3H₂SO₄ (aq) + 2Al (s) → Al₂SO₄ (aq) + 3H₂ (g)

(d) 6HCl (aq) + 2Fe (s) → 2FeCl₃ (aq) + 3H₂ (g)