Question

Hydrogen has three isotopes $\left(A\right),\left(B\right)$ and $\left(C\right)$. If the number of neutron(s) in (A), (B) and (C) respectively, are $\left(x\right),\left(y\right)$ and $\left(z\right)$, the sum of $\left(x\right),\left(y\right)$ and $\left(z\right)$ is :

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Answer 1

Hydrogen has three isotopes:

Isotopes	Number of neutrons
Protium ${(}_1^{1}H)$	$0$
Deutrium ${(}_1^{2}H)$	$1$
Tritium ${(}_1^{3}H)$	$2$

The sum is $3$