A solution consists of 0.2 M ` NH_4 OH and 0.2 M NH_4Cl . ` If `K_b of NH_4 OH is 1. 8 xx 10 ^(-5) , `the `[OH^(-) ]` of the resulting solution is

Options

A. `0.9 xx 10 ^(-5) M`
B. ` 1.8 xx 10 ^(-5) `
C. ` 3.2 xx 10 ^(-5) M`
D. ` 3. 6 xx 10 ^(-5) ` M

Answer

B

Explanation

`pOH =P^(K_b) + log ""( [S])/([B]) `
If ` [S] =[B] rArr pOH = P^(K_b) rArr [OH^(-) ] =K_b`