Question

In the following nuclear reaction,
$D \stackrel{α}{⟶} D1 \stackrel{β^-}{⟶} D2 \stackrel{α}{⟶} D3 \stackrel{γ}{⟶} D4$
Mass number of D is 182 and atomic number is 74. Mass number and atomic number
of D 4, respectively, will be _____.

• A. 174 and 71
• B. 174 and 69
• C. 172 and 69
• D. 172 and 71

Answer 1

Answer: (A)

174 and 71

Answer 2

The correct answer is (A) : 174 and 71
Equivalent reaction can be written as
D → D 4 + 2α + β– + γ
⇒ Mass number of D 4 = Mass number of D – 2 × 4
= 182 – 8 = 174
⇒ Atomic number of D 4
= Atomic number of D – 2 × 2 + 1
= 74 – 4 + 1
= 71