JEE Main · 2020 · 09 Jan 2020 · Shift 2 · Hydrogen

5 g of zinc is treated separately with an excess of
(a) dilute hydrochloric acid and
(b) aqueous sodium hydroxide.

The ratio of the volumes of

H_{2}

evolved in these two reactions is : -

Answer: (B)

Solution

Zinc reacts with dilute hydrochloric acid,

Zn + 2HCl \to ZnC l_{2} + H_{2}

, and with aqueous sodium hydroxide,

Zn + 2NaOH \to N a_{2} Zn O_{2} + H_{2}

. In each case one mole of zinc liberates exactly one mole of hydrogen, and since the same

5 g

of zinc is used both times, the moles of zinc and hence the volumes of hydrogen are identical. The ratio of the hydrogen volumes is

1 : 1

JEE Main · 2020 · 09 Jan 2020 · Shift 2 · Single correct option