JEE Main 2020 · ChemistryMultiple choiceSingle correctMediumMulti-step

JEE Main 5 September 2020, Shift 1, Chemistry Q40

Question 40 of 75 in this shift, Chemistry question 15 of 25.

A diatomic molecule

\mathrm{X_2}

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

\mathrm{X_2}

is : (Avogadro constant (

\mathrm{N_A}

)

= 6\times10^{23}\ \mathrm{mol^{-1}}

)

(1) $2\ \mathrm{N_A}$
(2) $4\ \mathrm{N_A}$ Official answer
(3) $40\ \mathrm{N_A}$
(4) $8\ \mathrm{N_A}$

Official answer

Option 2

NTA final key (Sep 2020).

Chapter: The Solid State
Topic: Crystal Lattices
Idea tested: Unit Cell Density

Same idea in other shifts

Asked 9× in all

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3 Sep 2020, Shift 1 · Q47An element with molar mass $2.7\times10^{-2}$ $\mathrm{kg\ mol^{-1}}$ forms a cubic unit cell with edge length 405 pm. If its density is…MediumNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.