Question

Following statements related to radioactivity are given below:
(A) Radioactivity is a random and spontaneous process and is dependent on physical and chemical conditions.
(B) The number of un-decayed nuclei in the radioactive sample decays exponentially with time.
(C) Slope of the graph of loge (no. of undecayed nuclei) Vs. time represents the reciprocal of mean life time (τ).
(D) Product of decay constant (λ) and half-life time (T1/2) is not constant.
Choose the most appropriate answer from the options given below:

• A. (A) and (B) only
• B. (B) and (D) only
• C. (B) and (C) only
• D. (C) and (D) only

Answer 1

Answer: (C)

(B) and (C) only

Answer 2

Radioactive decay is a random and spontaneous process it depends on unbalancing of nucleus.
N = N0e–λt …(B)
ln N = –λt + lnN0
So, slope = – λ …(C)
t1/2=$\frac{ln2}{lλ}$
So t1/2 × λ = ln2 = Constant