Question

The atomic number of bromine is 35 and its atomic weight is 80. Two isotopes of bromine are present in equal amounts. Which of the following statement represents the correct number of neutrons. First isotope Second isotope

(a) First isotope - 34, Second isotope - 36

(b) First isotope - 44, Second isotope - 46

(c) First isotope - 45, Second isotope - 47

(d) First isotope - 79, Second isotope - 81

Answer 1

Correct option is (b) First isotope - 44, Second isotope - 46

Isotopic mass of A(44 + 35 = 79) and that of B(46 + 35 = 81)

Average atomic mass = \(\frac{79 + 81}2 \) = 80