Atomic Nucleus|. Practice MCQs Physics for Mdcat By Engr. Kamran Soomro | mosaicbro.com

Atomic Nucleus|. Practice MCQs Physics for Mdcat By Engr. Kamran Soomro

7 of 114 questions (Page 6 of 17)

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36 Radioactivity was discovered by:
Correct Answer: A
Explanation: Henri Becquerel discovered radioactivity in 1896.
37 $\alpha$, $\beta$ and $\gamma$ rays are emitted from a radio-active substance:
Correct Answer: A
Explanation: Radioactive decay is a spontaneous process independent of external conditions.
38 Curie is a unit of:
Correct Answer: D
Explanation: The curie (Ci) measures radioactive decay rate (e.g., 1 Ci = 3.7 × 10¹⁰ decays per second).
39 The reciprocal of decay constant ($\lambda$) of a radioactive elements is:
Correct Answer: B
Explanation: Mean life ($\tau$) is the average time a nucleus exists before decaying: $\tau = 1/\lambda$.
40 An alpha particle is emitted from $\text{Na}^{226}$. What is the mass and atomic number of the daughter nucleus?
Correct Answer: C
Explanation: Alpha decay reduces mass by 4 and atomic number by 2: $\text{Na}^{226} \rightarrow \text{Rn}^{222} + \alpha$.
41 $\beta$-particles are:
Correct Answer: B
Explanation: Beta particles are high-energy electrons (or positrons) emitted during beta decay.
42 Gamma rays consist of a stream of:
Correct Answer: C
Explanation: Gamma rays are electromagnetic radiation (high-energy photons).
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