Question

2. Helium atom has an atomic mass
of 4 u and two protons in its
nucleus. How many, neutrons
does it have?​

Answer 1

since helium has atomic mass of 4u

number of protons and neutrons will be equal

i.e two protons and two neutrons

Answer 2

☆$\red {HELLO\:DEAR}$☆

Helium atom has two neutrons.

The mass of an atom is the sum of the masses of protons and neutrons present in its nucleus.

Since helium atom has two protons, mass contributed by the two protons is (2 × 1) u = 2 u.

Then, the remaining mass (4 − 2) u = 2 u is contributed by 2u/1u = 2 neutrons.

☆$\green {VISHU\:PANDAT}$☆

☆$\blue {FOLLOW\:ME}$☆