Question

A plant virus is found to consist of uniform cylindrical particles $150\dot{A}$ in diameter and $5000\dot{A}$ long. The specific volume of the virus is $0.75{cm}^3/g$. If the virus is considered to be a single particle and its molar mass is $7.09\times {10}^n$, then the value of $n$ is:

Answer 1

Volume of virus $=\pi r^{2}l$
$=\frac{22}{7}\times \frac{150}{2}\times \frac{150}{2}\times {10}^{-16}\times 5000\times {10}^{-8}$ $=0.884\times {10}^{-16}cm3$
Mass of one virus $=\frac{0.884\times {10}^{-16}}{0.75}g$ $=1.178\times {10}^{-16}g$
Molar mass of virus $=1.178\times {10}^{-16}\times 6.02\times {10}^{23}$ $=7.09\times {10}^7$
So, value of n is $7$.