Question

3. An atom with atomic number 18 and mass number 40, has the following arrangement:
(a) 18 p, 18 e, 22 n
(c) 22 p, 18e , 18 n
(b) 18 p, 18 e, 40 n
(d) 22 p, 22 e, 18 n​

Answer 1

Explanation:

hope it helps you

Answer 2

The correct option is a.

• The atomic number of an atom defines its number of electrons. Thus the atom has 18 electrons.
• Again the number of electrons in a species is equal to its number of protons.
• So, the number of protons in the species is also 18.
• The mass number of an atom is a sum of the number of protons and the number of neutrons.
• Thus the number of neutrons in the atom is 40-18=22.