JEE Main 2021 Question Paper (27-Aug-2021) (Shift 1)

Question 1

Which refining process is generally used in the purification of low melting metals?

Accepted Answer

Liquation

Answer

Chromatographic method

Answer

Electrolysis

Answer

Zone refining

Question 2

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Synthesis of ethyl phenyl ether may be achieved by Williamson synthesis. Reason (R): Reaction of bromobenzene with sodium ethoxide yields ethyl phenyl ether. In the light of the above statements, choose the most appropriate answer from the options given below.

Accepted Answer

(A) is correct but (R) is not correct

Answer

Both (A) and (R) are correct but (R) is NOT the correct explanation of (A).

Answer

(A) is not correct but (R) is correct

Answer

Both (A) and (R) are correct and (R) is the correct explanation of (A).

Question 3

In which one of the following molecules is the strongest back donation of an electron pair from halide to boron expected?

Accepted Answer

$\mathrm{BF}_3$

Answer

$\mathrm{BI}_3$

Answer

$\mathrm{BBr}_3$

Answer

${\mathrm{BCl}}_{3}$

Question 4

In the following sequence of reactions the $ \mathrm{P} $ is:

Accepted Answer

""

Answer

Answer

Answer

Question 5

The unit of the van der Waals gas equation parameter $'a'$ in $\left(P + \frac{a n^{2}}{V^{2}}\right)(V - n b) = nRT$ is:

Accepted Answer

$\mathrm{atm} \quad \mathrm{dm}^6 \quad \mathrm{mol}^{-2}$

Answer

$\mathrm{dm}^3 \quad \mathrm{mol}^{-1}$

Answer

$\mathrm{kg} \quad \mathrm{m\,s}^{-1}$

Answer

$\mathrm{kg} \quad \mathrm{m\,s}^{-2}$