Q.A bill of exchange must contain "an unconditional promise to pay." Do you agree with the statement?

No — a bill of exchange contains an unconditional ORDER to pay, not a promise; it is the promissory note that contains an unconditional promise.

The statement is incorrect. Under the Negotiable Instruments Act, 1881:

• A bill of exchange contains an unconditional order by the drawer (creditor) directing the drawee (debtor) to pay a certain sum. It has three parties and requires acceptance by the drawee.
• A promissory note contains an unconditional promise by the maker (debtor) to pay a certain sum. It has two parties and needs no acceptance.

So an unconditional promise to pay is the essential feature of a promissory note, whereas a bill of exchange embodies an unconditional order. The two must not be confused.