a. Choose the best definition for mass number. Mass number is the mass of an ato

Question

a. Choose the best definition for mass number. Mass number is the mass of an atom. Mass number is the mass of all protons in an atom. Mass number is the sum of the number of protons and the number of neutrons for an atom. Mass number is the sum of the number of neutrons and electrons for an atom. What is the difference between mass number and atomic mass? Atomic mass is the mass of an atom when the mass is expressed in u, the mass of a proton and of a neutron are both approximately one. Because the mass of electrons is small relative to that of a proton or neutron, the mass number approximates the atomic mass. Atomic mass is the mass of an atom. When mass expressed in the mass of a proton and of a neutron are both relatively small. Because the mass of electrons is one, the mass number approximates the atomic mass. Atomic mass is the mass of an atom. When the mass is expressed in u, the mass of a proton and of a neutron are both approximately one. Because the mass of electrons is small relative to that of a proton or neutron, the mass exactly equals the atomic mass. Atomic mass is the mass of an atom. When the mass is expressed in u, the mass of a proton and of a neutron are both approximately one. Because the mass of electrons is also one, the mass number approximates the atomic mass.

Explanation / Answer

Ans a) C) mass number is the sum of the number of protons and the number of neutrons of the atom .

As the atom has 3 subatomic particles , namely electrons , protons and neutrons . The electrons have a very negligible mass so the mass number is determined by the addition of number of protons and neutrons.

b) A) The atomic mass is the amss of atom . When the mass is expressed in u , the mass of a proton and a neutron are both approximately one. Because the mass of electrons is small relative to that of protons or a neutron , the mass number approximates the atomic mass.

Though the electron has very negligible mass 9.31x 10 -31 kg , but it cannot be ignored as it is of significant importance in many chemical and nuclear reaction. So the mass number may not be exactly as same as the atomic mass , but it closely approximates it.

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