Which of the following pairs is an isobar
$_1{H^1}$ and $_1{H^2}$
$_1{H^2}$ and $_1{H^3}$
$_6{C^{12}}$ and $_6{C^{13}}$
$_{15}{P^{30}}$ and $_{14}S{i^{30}}$
In the following reaction $_{12}M{g^{24}}{ + _2}H{e^4}{ \to _{14}}S{i^X}{ + _0}{n^1},X$ is
The mass number of a nucleus is
Mass numbers of two nuclei are in the ratio of $4: 3$. Their nuclear densities will be in the ratio of
Mark the correct statement
In the nucleus of ${ }_{11} N a^{23}$, the number of protons, neutrons and electrons are