A agrees to pay Rs. 500 to B if it rains, and B promises to pay a like amount to A if it does not rain. This agreement is called

This is a classic wagering agreement where both parties stake money on an uncertain event (rain). Wagering agreements are void under Section 30 of the Indian Contract Act. Unlike contingent contracts where the uncertain event is collateral to the main purpose, in wagering agreements, the event is the sole purpose of the agreement.