If ammonia is added to pure water, the concentration of a chemical species already present will decrease. The species is

Options

A. `O_(2)^(Theta)`
B. `overset(Theta)OH`
C. `H_(3)O^(o+)`
D. `H_(2)O`

Answer

C

Explanation

`NH_(3) +H_(2)O rarr NH_(4)^(o+) + overset(Theta)OH`
`H_(2)O +H_(2)O rarr H_(3)O^(o+) +overset(Theta)OH`
Due to common ion `[OH^(Theta)]`, the self ionisation of `H_(2)O` is supressed so the concentration of `H_(3)O^(o+)` is decreased.