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JEE Main 2024 (6 Apr, Shift 2) · Units & Dimensions

Units & Dimensions question from JEE Main 2024 (6 Apr, Shift 2)

Q31JEE Main 2024 · 6 APR · SHIFT 2Medium

Units & Dimensions

Given below are two statements:

Statement (I): Dimensions of specific heat is [L2T−2K−1][\mathrm{L^{2}T^{-2}K^{-1}}].

Statement (II): Dimensions of gas constant is [ML2T−1K−1][\mathrm{ML^{2}T^{-1}K^{-1}}].

In the light of the above statements, choose the most appropriate answer from the options given below.

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Answer: (d)

  1. Specific heat c=Qm ΔT=[ML2T−2][M][K]=[L2T−2K−1]c = \dfrac{Q}{m\,\Delta T} = \dfrac{[\mathrm{ML^2T^{-2}}]}{[\mathrm{M}][\mathrm{K}]} = [\mathrm{L^2T^{-2}K^{-1}}], so Statement I is correct.
  2. Gas constant R=PVnTR = \dfrac{PV}{nT} = energy per mole per kelvin =[ML2T−2K−1mol−1]= [\mathrm{ML^2T^{-2}K^{-1}mol^{-1}}].
  3. Statement II has T−1\mathrm{T^{-1}} (and no mol), so it is incorrect.
  4. So the answer is (d).
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