Question

Which of the following pairs of substances would give same gaseous product on reaction with water?

• A. $Na$ and $ N{{a}_{2}}{{O}_{2}} $
• B. $ Ca $ and $ Ca{{H}_{2}} $
• C. $Ca$ and $CaO$
• D. $Ba$ and $ Ba{{O}_{2}} $
• E. $Ca$ and $ Ca{{C}_{2}} $

Answer 1

Answer: (B)

The given substances react with water in the following manner
$ Na+{{H}_{2}}O\xrightarrow{{}}NaOH+{{H}_{2}}(g) $
$ 2N{{a}_{2}}{{O}_{2}}+2{{H}_{2}}O\xrightarrow{{}}4NaOH+{{O}_{2}}(g)+{{H}_{2}}(g) $
$ Ca+{{H}_{2}}O\xrightarrow{{}}CaO+{{H}_{2}} $
$ Ca{{H}_{2}}+2{{H}_{2}}O\xrightarrow[{}]{{}}Ca{{(OH)}_{2}}+2{{H}_{2}} $ $ CaO+{{H}_{2}}O\xrightarrow[{}]{{}}Ca{{(OH)}_{2}} $
$ Ca{{C}_{2}}+2{{H}_{2}}O\xrightarrow{{}}Ca{{(OH)}_{2}}+{{C}_{2}}{{H}_{2}} $
$ Ba+2{{H}_{2}}O\xrightarrow{{}}Ba{{(OH)}_{2}}+{{H}_{2}} $
$ Ba{{O}_{2}}+{{H}_{2}}O\xrightarrow{{}}B{{a}^{2+}}+{{O}_{2}}+{{H}_{2}}{{O}_{2}} $
Hence, $ Ca $ and $ Ca{{H}_{2}} $ is the pair that gives same gaseous product on reaction with water.