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

Options

A. a)`Na and Na_2O_2`
B. b)`Ca and CaH_2`
C. c)`Ca and CaO`
D. d)`Ba and BaO_2`

Answer

B

Explanation

The given substances react with water in the following manner
`Na+H_2 O to NaOH+H_2(g)`
`Ca+H_2O to 4NaOH +O_2(g)+H_2(g)`
`Ca+H_2O to CaO+H_2`
`CaH_2+ 2H_2O to Ca(OH)_2`
`CaC_2+ 2H_2O to Ca(OH)_2+C_2H_2`
`Ba+ 2H_2O to Ba(OH)_2+ H_2`
`BaO_2+ H_2O to Ba^(2+) +O_2+H_2O_2`
Hence, Ca and `CaH_2` is the pair that gives same gaseous product on reaction with water.