Verified Solution • 2025–26 Session moderate

QJEEM20Cha170: JEE Main 2020 Chemistry - Class 12 JEEM20Cha170 Solution: A diatomic molecule X 2 has a body-centred cubic (bcc)…

A diatomic molecule X2 has a body-centred cubic (bcc) structure with a cell edge of 300 pm. The density of the molecule is 6.17 g cm–3. The number of molecules present in 200 g of X2 is :
(Avogadro constant (N A) = 6 ×\times 1023 mol–1 )

Multiple Choice Options

  • A 8 NA
  • B 40 NA
  • C 4 NA
  • D 2 NA

Step-by-Step Verified Solution

d = Z×Ma3×NA{{Z \times M} \over {{a^3} \times {N_A}}}

⇒\Rightarrow 6.17 = 2×M(3×10−8)3×6×1023{{2 \times M} \over {{{\left( {3 \times {{10}^{ - 8}}} \right)}^3} \times 6 \times {{10}^{23}}}} [For BCC Z = 2]

⇒\Rightarrow M = 50 g/mol

Number of moles in 200 gm = 20050{{{200} \over {50}}} = 4

∴\therefore Number of molecules = 4 ×\times NA

Related Learning Resources & Exam Preparation

JEE Main PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring