Which of the following is/are NOT true about revenue receipts?
I. They are receipts of the government which are non-redeemable.
II. They can be claimed from the government under special circumstances.

Revenue receipts are those receipts of the government that neither create any liabilities nor cause any reduction in assets.
Statement I is true: Revenue receipts are non-redeemable, meaning the government is under no obligation to return or repay them.

Statement II is false: Because they are non-redeemable, they cannot be claimed back from the government under any circumstances.

Since the question asks for what is NOT true, only Statement II is incorrect.