A certain compound has a molecular formula $A_4{O}_6$ .  10 gm of $A_4{O}_6$  contains 5.72 gm of ‘A’. Atomic weight of ‘A’ is

Let atomic weight of ‘A’ be xg

Gram atomic mass of Oxygen = 16 g

$\therefore$  Gram molecular weight of $A_4{O}_6-(4x+96)g$

10g of $A_4{O}_6$  contain 5.72g of ‘A’ and 4.28g Oxygen.

$\therefore$  Percentage of Oxygen = 42.8%

Percentage of Oxygen in $A_4{O}_6$

$=\frac{\text{weight of Oxygen}}{\text{Molecular weight of }{A}_4{O}_6}\times 100$

$\therefore \frac{96}{4x+96}\times 100=42.8$  or $9600=171.2x+4108.8$  or $5491.2=171.2x$

X = 32 (approximately)

So, atomic weight of A = 32.