On litre of `0.15 M Na_(2)SO_(3)` aqueons solution is mixed with 500 mL of `0.2 M K_(2)Cr_(2)O_(7)` aqueous solution in acid medium. What is the number of moles of `K_(2) Cr_(2)O_(7)` remaining in the solution after the reaction ?

Options

A. 0.1
B. 0.0125
C. 0.025
D. 0.05

Answer

D

Explanation

When `0.15 M Na_(2)CO_(3)` (1L) mixed with `0.2 M K_(2)Cr_(2)O_(7)(5L)` than total molarity (M)
`M=(M_(1)V_(1)+M_(2) V_(2))/(V_(3))`
`M=(0.15xx1+0.2xx0.5)/(1 cdot 5)`
M=0.15 mol/L
Remaining mole of `K_(2) Cr_(2)O_(7) =0.2-0.15`
`=0.05` mol/L