Q79 · CSIR NET Chemistry, December 2011
Paper: CSIR NET December 2011 · Subject: Physical Chemistry · Chapter: Atomic and Molecular Term Symbol · Topic: Atomic And Molecular Term Symbols – General · Marks: 2 · Difficulty: Medium
Two $\alpha$ particles having speeds $\mathrm{S}_{1}$ and $\mathrm{S}_{2}$ have kinetic energies 1 and 2 MeV respectively; the relationship between $\mathrm{S}_{1}$ and $\mathrm{S}_{2}$ is :
(a)$\mathrm{S}_{1}=2 \mathrm{S}_{2}$
(b)$\mathrm{S}_{2}=2 \mathrm{S}_{1}$
(c)$\mathrm{S}_{2}=\sqrt{2} \mathrm{S}_{1}$
(d)$\mathrm{S}_{1}=\sqrt{2 \mathrm{S}_{2}}$
Answer
Answer: C ✓ checked by 4AB · confidence high
The source book printed B; on checking, C is correct — see the explanation.
Explanation
KE ∝ speed² at the same mass: S₂²/S₁² = 2 ⇒ S₂ = √2 S₁.
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