Mole Concept & Stoichiometry · JEE Main previous year questions

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2026 29 questions

Q532026 · 21 Jan 2026 · Shift 1
An organic compound $(P)$ on treatment with aqueous ammonia under hot condition forms compound $(Q)$ which on heating with $B r_{2}$ and KOH forms compound $(R)$ having molecular formula $C_{6} H_{7} N$ . Names of P, Q and R respectively are.
1. A.Toluic acid, methylbenzamide, 2-methylaniline
2. B.Benzoic acid, benzamide, aniline
3. C.Benzoic acid, 4-methylbenzamide, 4-methylaniline
4. D.Phenylethanoic acid, phenylethanamide, benzamine
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Answer: B
Q562026 · 21 Jan 2026 · Shift 1
1. A.
2. B.
3. C.
4. D.
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Answer: B
Q582026 · 21 Jan 2026 · Shift 1
An organic compound " P " of molecular formula $C_{6} H_{12} O_{3}$ gives positive Iodoform test but negative Tollen's test. When " P " is treated with dilute acid, it produces " Q ". " Q " gives positive Tollen's test and also iodoform test. The structure of " P " is :
1. A. $H - CO - C H_{2} - C H_{2} - CH (OC H_{3}) - OC H_{3}$
2. B. $C H_{3} - CO - CH (OC H_{3}) - C H_{2} (OC H_{3})$
3. C. $C H_{3} - CO - C H_{2} - CH (OC H_{3}) - OC H_{3}$
4. D. $C H_{3} - CO - C (OC H_{3})_{2} - C H_{3}$
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Answer: C
Q722026 · 21 Jan 2026 · Shift 1· Numerical answer
Use the following data : $Substance AB (g) A_{2} (g) B_{2} (g) \frac{Δ _{f} H ^{⊖} ( 500 K )}{kJ mo l ^{- 1}} 326 x \frac{S ^{⊖} ( 500 K )}{J K ^{- 1} mo l ^{- 1}} 222146280$ One mole each of $A_{2} (g)$ and $B_{2} (g)$ are taken in a 1 L closed flask and allowed to establish the equilibrium at 500 K . $A_{2} (g) + B_{2} (g) ⇌ 2AB (g)$ The value of $x$ $(in kJ mo l^{- 1})$ is ____. (Nearest integer) (Given : $lo g K = 2.2 R = 8.3 J K^{- 1} mo l^{- 1}$ )
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Answer: 70