Which waves are used in the treatment of cancer?

Out of the following, which one is not emitted by a natural radioactive substance?

The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter nucleus is an

In the emission of $\gamma$-rays from a nucleus:

If a heavy nucleus has an $N/Z$ ratio higher than that required for stability,then:

Assertion : The ionising power of $\beta$-particle is less compared to $\alpha$-particles but their penetrating power is more.
Reason : The mass of $\beta$-particle is less than the mass of $\alpha$-particles.