A radioactive element `A` decays by the sequence and with half-lives given below:
`A underset(alpha)overset(30 "min"rarr B underset(2 beta)overset(2 "days")rarr C`
Which of the following statement about this system are correct?

Options

A. The mass number of `B` is greater then `A`.
B. After two hours, less than 10% of the initial `A` is left.
C. Maximum amount of `B` present at any time is less than 50% of the initial amount of `A`.
D. The atomic numbers of `A` and `C` are the same.

Answer

B, D

Explanation

2 hours = 4 half lives, therefore, amount left = 6.25% of original. Loss of one `alpha`particle and two `beta`-particles does not change the atomic number.