Is alcohol (human consumption) an exempt good

Yes, alcohol is an exempt good though it is not leviable to tax. It is required to treat all non-leviable goods and leviable-but-non-taxable goods to be classified as exempt goods in order to restrict input tax credit.

(ICAI FAQ PUBLICATION 06-09-2017 EXEMPTION ON SUPPLY OF GOODS: FAQ NO. 22)

Petrol is exempt good or non-taxable good

Five petroleum products i.e., petroleum crude, high speed diesel, motor spirit, natural gas and aviation turbine fuel are excluded from levy for the time being and as such petrol is non-taxable good.

(ICAI FAQ PUBLICATION 06-09-2017 EXEMPTION FROM SUPPLY OF GOODS: FAQ NO. 21)

Where do we find exemption for high sea sales

There is no exemption that is specifically issued for high sea sales. All import of goods are liable to IGST not under section 5(1) but under the proviso which takes imported goods into the Customs Act for determination of the liability. And ‘the point’ at which customs duties are levied is when bill of entry for home consumption is filed. In case of high sea sales, such a bill of entry is filed only by the final recipient (high sea buyer).

(ICAI FAQ PUBLICATIONS 06-09-2017 EXEMPTIONS: FAQ NO. 15)