Q46 · CSIR NET Chemistry, December 2019
Paper: CSIR NET December 2019 · Subject: Physical Chemistry · Chapter: Molecular Spectroscopy · Topic: Molecular Spectroscopy – General · Marks: 2 · Difficulty: Easy
The atomic masses of fluorine and hydrogen are 19.0 and 1.0 amu, respectively (1 amu = $1.67 \times 10^{-27}$ kg). The bond length of HF is 2.0 Å. The moment of inertia of HF is
(a)$3.2 \times 10^{-47}\ \mathrm{kg\,m^2}$
(b)$6\text{-}4 \times 10^{-47}\ \mathrm{kg\,m^2}$
(c)$9\text{-}6 \times 10^{-47}\ \mathrm{kg\,m^2}$
(d)$4.8 \times 10^{-47}\ \mathrm{kg\,m^2}$
Answer
Answer (as printed): B
Explanation
F atomic mass = 19.0amu . H atomic mass = 1 amu H – F bond length =2 . 0 Å °/ °- I = 𝜇𝑟 0 , I = 𝑟0 °/ .°- 8Ä×8 Å°Æ - 8Ä I= ×2.0Å×2.0Å = 𝑎𝑚𝑢 ×2.0×2.0×Å0 0“Å°Æ 0 19×1.67×10107 𝑘𝑔×4 = ×1018“ × 1018“ 𝑚0 20 76×1.67×101P7 𝑘𝑔𝑚0 = 6.4×101P7 𝑘𝑔𝑚0 20
Explanation as extracted from the printed page; notation may be imperfect.
Study loop for Molecular Spectroscopy