JEE Main 2020 Question Paper (06-Sep-2020) (Shift 2)

Question 1

For a reaction $4\, \mathrm{M}(\mathrm{s}) + n\mathrm{O}_2(\mathrm{g}) \to 2\mathrm{M}_2\mathrm{O}_n(\mathrm{s})$, The free energy change is plotted as a function of temperature. The temperature below which the oxide is stable could be inferred from the plot as the point at which:

Accepted Answer

The free energy change shows a change from negative to positive value.

Answer

The slope changes from negative to positive

Answer

The slope changes from positive to negative

Answer

The slope changes from positive to zero.

Question 2

The average molar mass of chlorine is $35.5  \mathrm{g}  \mathrm{mol}^{-1}$. The ratio of ${}^{35}\mathrm{Cl}$ to ${}^{37}\mathrm{Cl}$ in naturally occurring chlorine is close to:

Accepted Answer

$3 \;:\; 1$

Answer

$4 \;:\; 1$

Answer

$2 \;:\; 1$

Answer

$1 \;:\; 1$

Question 3

Which one of the following statements is not true?

Accepted Answer

Lactose contains $\mathrm{\alpha}$-glycosidic linkage between ${\mathrm{C}}_{1}$ of galactose and ${\mathrm{C}}_{4}$ of glucose.

Answer

Lactose is a reducing sugar and it gives Fehling's test.

Answer

Lactose $\left(\mathrm{C}_{12}\mathrm{H}_{22}\mathrm{O}_{11}\right)$ is a disaccharide and it contains $8$ hydroxyl groups.

Answer

On acid hydrolysis, lactose gives one molecule of $\mathrm{D}(+)$-glucose and one molecule of $\mathrm{D}(+)$-galactose.

Question 4

The value of $K_{\mathrm{c}}$ is 64 at 800 K for the reaction $ \mathrm{N}_2(g) + 3\mathrm{H}_2(g) 	o 2\, \mathrm{NH}_3(g) $ The value of $K_{\mathrm{c}}$ for the following reaction is: $ \mathrm{NH}_3(g) 	o \frac{1}{2} \mathrm{N}_2(g) + \frac{3}{2} \mathrm{H}_2(g) $

Accepted Answer

$ \frac{1}{8} $

Answer

$ \frac{1}{64} $

Answer

$8$

Answer

$ \frac{1}{4} $

Question 5

Dihydrogen of high purity $ \left(>99.95 \%\right)$ is obtained through :

Accepted Answer

The electrolysis of warm $ \mathrm{Ba}{\left(\mathrm{OH}\right)}_{2}$ solution using $ \mathrm{Ni}$ electrrodes.

Answer

The reaction of $ \mathrm{Zn}$ with dilute $ \mathrm{HCl}$.

Answer

The electrolysis of acidified water using $ \mathrm{Pt}$ electrodes.

Answer

The electrolysis of brine solution.