Question

Calculate the mass of a proton if the charge to mass ratio of an electron is $1.758820\times {10}^{11}{\text{C kg}}^{-1}$ and it is known that the mass of a proton is 1837 times greater than the mass of an electron.

• A. $9.1\times {10}^{-31}$ kg
• B. $6.4\times {10}^{31}$ kg
• C. $1.67\times {10}^{-27}$ kg
• D. $6.02\times {10}^{23}$ kg

Answer 1

The correct option is C $1.67\times {10}^{-27}$ kg

$\frac{e}{m}=1.758820\times {10}^{11}{\text{C kg}}^{-1}$
We know that, $e=1.602\times {10}^{-19}$ C
So, mass of electron = $9.1\times {10}^{-31}$ kg
Also the mass of a proton is 1837 times the mass of an electron. So, mass of proton $=1837\times 9.1\times {10}^{-31}\text{kg}=1.67\times {10}^{-27}\text{kg}$