JEE Main 2020 Question Paper (03-Sep-2020) (Shift 1)

Question 1

Henry's constant (in kbar) for four gases $\alpha, \beta, \gamma$ and $\delta$ in water at $298 \quad \mathrm{K}$ is given below : $ \begin{array}{ccccc} & \alpha & \beta & \gamma & \delta \ K_{\mathrm{H}} & 50 & 2 & 2 	imes 10^{-5} & 0.5 \end{array} $ (density of water $= 10^{3} \quad \mathrm{kg} \quad \mathrm{m}^{-3}$ at $298 \quad \mathrm{K}$) This table implies that :

Accepted Answer

The pressure of a $55.5$ molal solution of $\mathrm{\delta}$ is $250$ bar

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$ \alpha $ has the highest solubility in water at a given pressure.

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Solubility of $ \gamma $ at $ 308\,K $ is lower than at $ 298\,K $.

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The pressure of a $55.5$ molal solution of $\mathrm{\gamma}$ is $1 \quad \mathrm{bar}$.

Question 2

Which of the following compounds produces an optically inactive compound on hydrogenation?

Accepted Answer

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Question 3

An organic compound [A], molecular formula $\mathrm{C}_{10}\mathrm{H}_{20}\mathrm{O}_{2}$, was hydrolyzed with dilute sulphuric acid to give a carboxylic acid [B] and an alcohol [C]. Oxidation of [C] with $\mathrm{CrO}_3$-$\mathrm{H}_2\mathrm{SO}_4$ produced [B]. Which of the following structures are not possible for $\left[\mathrm{A}\right]$?

Accepted Answer

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$\mathrm{CH}_3\mathrm{CH}_2\mathrm{CH}_2\mathrm{COOCH}_2\mathrm{CH}_2\mathrm{CH}_2\mathrm{CH}_3$

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${\left(\mathrm{CH}_3\right)}_3-\mathrm{C}-\mathrm{COOCH}_2\mathrm{C}{\left(\mathrm{CH}_3\right)}_3$

Question 4

The mechanism of the SN1 reaction is given as: $ \mathrm{R}-\mathrm{X} \xrightarrow{} \mathrm{R}^{\oplus} + \mathrm{X}^{\ominus} \quad \Vert \quad \mathrm{X}^{\ominus} \xrightarrow{{\mathrm{Y}}^{\ominus}} \mathrm{R}-\mathrm{Y} + \mathrm{X}^{\ominus} $ $ 	ext{Ion pair} \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad 	ext{Solvent} \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad 	ext{Separated ion pair} $ A student writes general characteristics based on the given mechanism as: The reaction is favoured by weak nucleophiles. $\mathrm{R}^{\oplus}$ would be easily formed if the substituents are bulky. The reaction is accompanied by racemization. The reaction is favoured by non-polar solvents. Which observations are correct?

Accepted Answer

(a), (b) and (c)

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(a) and (b)

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(a) and (c)

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(b) and (d)

Question 5

Which one of the following compounds possesses the most acidic hydrogen?

Accepted Answer

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$\mathrm{H}_3\mathrm{C}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}$

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