1. Identify reaction of chromyl chloride with NaOH

Chromyl chloride is $\mathrm{CrO_2Cl_2}$. On hydrolysis/alkaline treatment, it gives chromate.

Let us balance the reaction:

$\mathrm{CrO_2Cl_2 + 4NaOH \rightarrow Na_2CrO_4 + 2NaCl + 2H_2O}$

Check atoms:

• Cr: $1=1$
• Cl: $2=2$
• Na: $4=2+2$
• O: $2+4=6$ on LHS, $4+2=6$ on RHS
• H: $4=4$

So,

$A = \mathrm{Na_2CrO_4}$

2. Now analyze the second reaction

Given:

$A + 2HCl + 2H_2O_2 \rightarrow B + 3H_2O$

Substitute $A = \mathrm{Na_2CrO_4}$.

First, acidification of chromate gives chromic acid type species, and in presence of hydrogen peroxide, chromium(VI) forms the deep blue peroxide compound $\mathrm{CrO_5}$.

A standard reaction is:

$\mathrm{CrO_4^{2-} + 2H^+ + 2H_2O_2 \rightarrow CrO_5 + 3H_2O}$

Thus,

$B = \mathrm{CrO_5}$

3. Match with options

We found:

$A = \mathrm{Na_2CrO_4}, \qquad B = \mathrm{CrO_5}$

This matches Option B.

4. Verification with stored correct answer

Stored correct answer: B

Our derived answer: B

So they agree.