Question

When the same amount of zinc is treated separately with excess sulfuric acid and excess sodium hydroxide solution the ratio of volumes of hydrogen evolved is
A. 1:1
B. 1:2
C. 2:1
D. 9:4

Answer 1

Hint: Zinc reacts with sulfuric acid, yields hydrogen gas along with zinc sulphate.
Zinc in reaction with sodium hydroxide solution produces sodium zincate (\[N{a_2}Zn{O_2}\]) along with hydrogen gas.

Complete Step by Step Answer:
Zinc is a chemical element depicted by the symbol Zn.
Its atomic number is 30.
Zinc is a little brittle metal at room temperature and possesses a silvery-greyish appearance when oxidation is removed.
It is the 1st element in group 12 of the periodic table.
In this question, it is given that the same amount of zinc is reacted individually with excess sulphuric acid and excess sodium hydroxide solution.

Zinc reacts with sulfuric acid, yields hydrogen gas along with zinc sulphate.
\[Zn + {H_2}S{O_4} \to ZnS{O_4} + {H_2}\]
From this equation, we see that one mole of Zinc gives rise to one mole of hydrogen gas.
Zinc in reaction with sodium hydroxide solution produces sodium zincate (\[N{a_2}Zn{O_2}\]) along with hydrogen gas.
\[Zn + 2NaOH \to N{a_2}Zn{O_2} + {H_2}\]
From this equation, we see that one mole of zinc gives rise to one mole of hydrogen gas.
Same amount of zinc gives rise to an equal amount of hydrogen gas.
So, when same amount of zinc is treated
individually with excess sulfuric acid and excess sodium hydroxide solution the ratio of volumes of hydrogen evolved is 1:1.
So, option A is correct.

Note: Zinc burns in air forming zinc oxide. Zinc undergoes reaction with acids, alkalis and other non-metals. Pure zinc reacts gradually at room temperature with acids. Strong acids like hydrochloric acid or sulfuric acid, can eliminate the unreactive coating of zinc oxide and react with the acid releasing hydrogen gas.