JEE Main 2021 · ChemistryNumerical answerNumerical valueMediumCalculation

JEE Main 25 February 2021, Shift 1, Chemistry Q53

Question 53 of 90 in this shift, Chemistry question 23 of 30, Section B.

The reaction of cyanamide,

\mathrm{NH_2CN_{(s)}}

with oxygen was run in a bomb calorimeter and

\Delta U

was found to be

-742.24

kJ mol

^{-1}

. The magnitude of

\Delta H_{298}

for the reaction

\mathrm{NH_2CN_{(s)} + \frac{3}{2}O_{2(g)} \rightarrow N_{2(g)} + O_{2(g)} + H_2O_{(l)}}

is ________ kJ. (Rounded off to the nearest integer) [Assume ideal gases and R = 8.314 J mol

^{-1}

^{-1}

]

Official answer

741

NTA final key.

Chapter: Thermodynamics (Chemistry)
Topic: Enthalpy and Hess's Law
Idea tested: Bomb Calorimetry Calculations

Same idea in other shifts

Asked 7× in all

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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.