A nuclear reaction given by

_ZX^A $$ \to $$ _z+1Y^A + _$$-$$1e⁰ + $$\overline v $$ represents

In which of the following systems will the radius of the first orbit (n = 1) be minimum ?

A deutron is bombarded on ₈O¹⁶ nucleus then $$\alpha $$-particle is emitted. The product nucleus is

A sample of radioactive element containing 4 $$ \times $$ 10¹⁶ active nuclei. Half life of element is 10 days, then number of decayed nuclei after 30 days