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

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

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Salim Ahmed Kawsar · Answer 1 · Feb 05, 2023 15:29:48

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.

Salim Ahmed Kawsar · Answer 2 · Feb 05, 2023 15:29:48

We know that atomic mass is numerically equal to mass number an atom. Since the helium atom as an atomic mass of 4u, therefore, the mass number of helium atom will be 4. And the number of protons in the helium nucleus has been given to be 2. How,
Mass number = No. of protons + No. of neutrons
So, 4 = 2 + No. of neutrons
And, No. of neutrons = 4 - 2
= 2
Thus, the helium atom has 2 neutrons.

Salim Ahmed Kawsar · Answer 3 · Feb 05, 2023 15:29:48

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.

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

3 Answers