what collatoral i should offer if i am asking for a small ampunt of loan. 0.5 btc
At current market price, 0.5 Bitcoin (BTC) = 3,468.36 USD [coinmarketcap]
Very Small "ampunt" indeed "Collateral" is for the security of the lender in case of default so that the lender can cut their losses. Offer a valid collateral or go away. I and other lenders here accept stable altcoins 120-150% of the loan value as valid collateral.