Question

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Answer 1

Answer:

Option B  is correct.

Explanation:

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.

All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. The number of protons or neutrons is the atomic number of an atom while sum of proton and neutrons is the mass number.

The beryllium atom have five neutrons, four protons and four electrons.

The option be is correct model of beryllium because it shows that there are four protons and five neutron in nucleus of beryllium atom and four electrons revolving around the nucleus.

Beryllium is alkaline earth metal.

It is present in group two.

Its atomic number is 4.

its atomic mass is 9 amu.