Question

complete the missing? (_5^11)B + ______ → (_6^13)C + (_1^1)H

Answer 1

Let us denote the unknown element by X. We assume it's atomic number to be Z and it's Atomic mass to be A.

$_5B^{11} +_ZX^{A} \to _6C^{13}+_1H^1$

Now, equating values for Z and A we get;

$11+A=13+1$

$\implies A=14-11$

$=3$

Similarly; $5+Z=6+1$

$\implies Z=2$

As, Atomic number is 2, clearly the element is Helium.

And as it's Atomic mass is 3, it has 1 neutron.

Thus the element $_ZX^{A}$ can be identified as $_2He^{3}$ , which the Helium-3 isotope of Helium.