Radioactivity was discovered by

The appreciable radioactivity of uranium minerals is mainly due to

The $\beta$-decay of $_{11}Na^{24}$ produces an isotope of

Which statement is incorrect?

An element with atomic number $84$ and mass number $218$ loses one $\alpha$-particle and two $\beta$-particles in three successive stages. The resulting element will have:

During a $\beta$-decay,the mass of the atomic nucleus