Question

Give secientific reasons.
A. All the mass of an atom is concenrated in the nucleus.
B. Atom is electrically neutral.
C. Atomic mass number is a whole number.
D. Atoms are stable though negatively charged electron are revolving within it.

Answer 1

a. All the mass of an atom is concentrated in the nucleus because atom contains three subatomic particles like electron, proton and neutron.Out of which, nucleus present at the centre of an atom contains two subatomic particles that's protons and neutrons and the mass of nucleus is the sum of mass of protons and neutrons located at the centre of an atom.

b.Atom is electrically neutral because in an atom electrons and protons carry charges and each atom has equal numbers of protons (positively charged) and electrons (negatively charged).

c.Atomic mass number is a whole number because it is the sum of numbers of protons and numbers of neutrons present in an atom.Which is present in the form of integers.

d.Atoms are stables though negatively charged electrons are revolving within it because each atom contains equal numbers of protons and electrons. So, charge on negatively charged electrons are balanced by charge on positively charged proton. Therefore, atom is electrically neutral and stable.