# A mixture consists of two radioactive materials A1 and A2 with half lives of 20 sec and 10 sec respectively. Initially, the mixture has 40 g of A1 and 160 g of A2. The active amount of the two in the mixture will becomes equal after?

A mixture consists of two radioactive materials A1 and A2 with half lives of 20s and 10s respectively. Initially, the mixture has 40 g of A1 and 160 g of A2. The active amount of the two in the mixture will become equal after?

1. 20 s
2. 60 s
3. 80 s
4. 40 s

The correct option is iv.40 s