An atomic substance A of molar mass $12 \mathrm{~g} \mathrm{~mol}^{-1}$ has a cubic crystal structure with edge length of 300 pm. The no. of atoms present in one unit cell of $A$ is $\_\_\_\_$ (Nearest integer) Given the density of $A$ is $3.0 \mathrm{~g} \mathrm{~mL}^{-1}$ and $N_{\mathrm{A}}=6.02 \times 10^{23} \mathrm{~mol}^{-1}$