The mass of 0.5 moles of the nitrogen atom is:

The mass of 0.5 moles of the nitrogen atom is 7g.
 

The atomic number of nitrogen is 7. So, the molecular weight of nitrogen is $7\times 2$ and the molecular weight of the nitrogen is 14g. The number of moles is represented as n given 0.5. Now, we calculate the mass of 0.5 moles of nitrogen 
Number of moles (n) = $\frac{\mathit{weight}}{\mathit{molecular\; weight}}$
Therefore, weight = n $\times$molecular weight 
           

Given n= 0.5
Molecular weight= 14
Weight = $0.5 \times 14$
           = 7g
Hence, the mass of 0.5 mole of nitrogen is 7g.