Atoms PYQs Set 16 (PDF)

Set 16 of 16 · Questions 451-453 of 453

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Mere Teacher · Previous Year Questions JEE Main Physics · Atoms · Set 16 (Q451-453)
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451. $Following statements related to radioactivity are given below: (A) Radioactivity is a random and spontaneous process and is dependent on physical and chemical conditions. (B) The number of un-decayed nuclei in the radioactive sample decays exponentially with time. (C) Slope of the graph of l o g_{e} (no. of undecayed nuclei) Vs. time represents the reciprocal of mean life time (τ). (D) Product of decay constant (λ) and half-life time (T_{1/2}) is not constant. Choose the most appropriate answer from the options given below:$ (1) $(A) and (B) only$ (2) $(B) and (D) only$ (3) $(B) and (C) only$ (4) $(C) and (D) only$ 452. $Alpha particles are$ (1) $neutrally charged$ (2) $positron$ (3) $protons$ (4) $ionized helium atoms$ 453. $Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: The nuclear density of nuclides,_{5}^{10} B,_{3}^{6} Li,_{26}^{56} Fe,_{10}^{20} Ne and,_{83}^{209} Bi can be arranged as ρ_{Bi}^{N} > ρ_{Fe}^{N} > ρ_{Ne}^{N} > ρ_{B}^{N} > ρ_{Li}^{N} . Reason R: The radius R of nucleus is related to its mass number A as R = R0 A^{l /3}, where R0 is a constant. In the light of the above statement, choose the correct answer from the options given below:$ (1) $Both A and R are true and R is the correct explanation of A$ (2) $A is false but R is true$ (3) $A is true but R is false$ (4) $Both A and R are true but R is NOT the correct explanation of A$