Question

If a neutral atom has $27.3\times {10}^{-31}kg$ of electrons, then the number of protons in the atom is:

• A. 3
• B. 4
• C. 1
• D. 2

Answer 1

The correct option is A 3

Atoms are made up of three subatomic particles: electron, proton and neutron. Electrons are negative charged and protons are positive charged and neutrons are neutral. Therefore, in a neutral atom, the number of electrons is equal to the number of protons.
$n_e{M}_e=27.3\times {10}^{-31}kg$
Where, $n_e$ is the number of electrons and $M_e$ is the mass of a single electron.
We know that,
$M_e=9.1\times {10}^{-31}kg$
On solving we get, number of electrons = 3 and number of protons = 3