JEE Main 2021 Question Paper (27-Aug-2021) (Shift 2)

Question 1

The oxide that gives ${\mathrm{H}}_{2}{\mathrm{O}}_{2}$ most readily on treatment with ${\mathrm{H}}_{2}\mathrm{O}$ is :

Accepted Answer

$\mathrm{Na}_2\mathrm{O}_2$

Answer

$\mathrm{BaO}_{2} \cdot 8 \mathrm{H}_{2}\mathrm{O}$

Answer

$\mathrm{SnO}_{2}$

Answer

$\mathrm{PbO}_{2}$

Question 2

The addition of dilute $\mathrm{NaOH}$ to $\mathrm{Cr}^{3+}$ salt solution will give :

Accepted Answer

precipitate of $\mathrm{Cr}_2\mathrm{O}_3(\mathrm{H}_2\mathrm{O})_n$

Answer

a solution of $\left[\mathrm{Cr}(\mathrm{OH})_{4}\right]^{-}$

Answer

precipitate of $\left[\mathrm{Cr}(\mathrm{OH})_{6}\right]^{3-}$

Answer

precipitate of $\mathrm{Cr}(\mathrm{OH})_{3}$

Question 3

The correct order of ionic radii for the ions, $ \mathrm{P}^{3-}, \quad \mathrm{S}^{2-}, \quad \mathrm{Ca}^{2+}, \quad \mathrm{K}^{+}, \quad \mathrm{Cl}^{-} $ is :

Accepted Answer

${\mathrm{P}}^{3-} > {\mathrm{S}}^{2-} > {\mathrm{Cl}}^{-} > {\mathrm{K}}^{+} > {\mathrm{Ca}}^{2+}$

Answer

$\mathrm{P}^{3-} > \mathrm{S}^{2-} > \mathrm{Cl}^{-} > \mathrm{Ca}^{2+} > \mathrm{K}^{+}$

Answer

$\mathrm{Cl}^{-} > \mathrm{S}^{2-} > \mathrm{P}^{3-} > \mathrm{Ca}^{2+} > \mathrm{K}^{+}$

Answer

$\mathrm{K}^{+} > \mathrm{Ca}^{2+} > \mathrm{P}^{3-} > \mathrm{S}^{2-} > \mathrm{Cl}^{-}$

Question 4

Choose the correct statement from the following :

Accepted Answer

Among the alkali metal halides, $\mathrm{LiF}$ is least soluble in water.

Answer

$ \mathrm{LiF} $ has the least negative standard enthalpy of formation among alkali metal fluorides.

Answer

The standard enthalpy of formation for alkali metal bromides becomes less negative on descending the group.

Answer

The low solubility of $\mathrm{CsI}$ in water is due to its high lattice enthalpy.

Question 5

The compound(s) which will show significant intermolecular $\mathrm{H}$-bonding is/are :

Accepted Answer

(b) only

Answer

(a), (b) and (c)

Answer

(c) only

Answer

(a) and (b) only