Hi sir but trader of goods registered as a composition dealer in GST is not required to pay GST on sale of Exempted goods. Refer notification no. 01/2018 (
No Chethana Kumar. The Composition Dealer ( TRADER ) is not required to pay tax on Exempt Supply ( Salt in your case ).
As per Notification No. 1/2018 - Central Tax, dated 01.01.2018 ( amending the Principal Notification No. 8/2017 - Central Tax, dated 27th June 2017), the Traders who have opted for Composition Scheme need to pay “half percent of the turnover of TAXABLE SUPPLIES of Goods."
Therefore the trader is required to pay 1% GST on their Taxable Supplies of Goods.