Question

A plant virus consists of uniform cylindrical particles of $150AA$ in diameter and $5000AA$ long. The specific volume of the virus is $0.75cm3/g$. If the virus is considered to be a single particle, its molecular mass is:

• A. $7.09\times {10}^{7}gmo{l}^{-1}$
• B. $8.09\times {10}^{7}gmo{l}^{-1}$
• C. $9.07\times {10}^{7}gmo{l}^{-1}$
• D. $9.70\times {10}^{7}gmo{l}^{-1}$

Answer 1

The correct option is A $7.09\times {10}^{7}gmo{l}^{-1}$

Volume = $\Pi (\frac{150\times {10}^{-}8}{2}{)}^2\times 5000\times {10}^{-8}c{m}^3$

=8.8 $\times {10}^{-17}c{m}^3$

If M is molecular mass, then M g contains 6.02 $\times {10}^{23}$ particles

Therefore , M =$\frac{8.8\times {10}^{17}}{0.75}\times 6.02\times {10}^{23}$

$=7.09\times {10}^7$ g/mol.