Supply of exempt Goods

Your query is not clear
pls elobrate your query
I think You are talking about ITC on exempted Goods
ITC on Exempted Good are not available, you can't claim ITC on supply of exempted Goods.

Why I can't claim itc

For exempted goods no ITC avilble

Because if it's outward supply exempted, non taxable hence no itc on pertaining on those supply
if no taxable supply how to claim itc on inward supply
just like matching principles

Goods exempted under GST already enjoy 0% GST. ITC cannot be claimed for inputs used in such exempted goods as it will lead to negative taxation. And as per a matching concept also if your outward supply is exempt than you can't claim ITC on purchase of same, because on exempted good you need not to pay any GST.

Please refer section 17(1), (2) and (3) read with Rule 42 & 43 of CGST law.