Reply for Question No 1:
Rice is one of the essential commodities used by common people. So Government is not charging GST for those essentials and most are classified as NIL RATE
However, when those items are sold in UNIT Container with a Registered BRAND NAME, they are charged GST.
So Branded Rice is charged @ 5% GST, whereas unbranded Rice is NIL RATE
Reply for Question No 2:
Composite Supply means when two or more goods, with the condition that It is a natural bundle, i.e., goods or services are usually provided together in the normal course of business. They cannot be separated. Like Sale of AC and installation of AC.
Since Pant and Belt can be sold separately, in my view they cannot be treated as composite supply.
Mixed Supply means a combination of two or more goods or services made together for a single price. Each of these items can be supplied separately and is not dependent on any other. Here the GST of the highest rate will be charged. So if Pant and Belt are bundled and sold as a single SKU, for a single price, then 18% will be charged for the bundle.
It is suggested to sell the pant and belt as separate SKUs and respective GST Charged