Hydrogen — Page 3 | JEE Chemistry

Q21

In comparison to the zeolite process for the removal of permanent hardness, the synthetic resins method is :

A less efficient as the resins cannot be regenerated.

B more efficient as it can exchange only cations.

C more efficient as it can exchange both cations as well as anions.

D less efficient as it exchanges only anions.

Correct Answer

Option C

Solution

Synthetic resin method is more efficient because it can exchange both cation & anion.

Q22

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Hydrogen is the most abundant element in the Universe, but it is not the most abundant gas in the troposphere. Reason R : Hydrogen is the lightest element. In the light of the above statements, choose the correct answer from the options given below :

A Both A and R are true but R is NOT the correct explanation of A

B Both A and R are true and R is the correct explanation of A

C A is true but R is false

D A is false but R is true.

Correct Answer

Option B

Solution

As we know, hydrogen is most abundant element in the universe but the most abundant gas in the troposphere is nitrogen, because hydrogen is lightest element.

Troposphere contains 3 quarters of mass of the entire atmosphere.

The air here contain 78% nitrogen and 21% oxygen.

The last 1% is made of argon, water vapour and carbon dioxide.

Q23

The number of neutrons and electrons, respectively, present in the radioactive isotope of hydrogen is :

A 1 and 1

B 3 and 1

C 2 and 1

D 2 and 2

Correct Answer

Option C

Solution

Radioactive isotope of hydrogen is Tritium (

_1^3

T) No. of neutrons (A $-$ Z) = 3 $-$ 1 = 2 No. of electrons = 1

Q24

Hydrogen peroxide reacts with iodine in basic medium to give :

A IO

_4^ -

B IO

-

C I

-

D IO

_3^ -

Correct Answer

Option C

Solution

I2 + H2O2 + 2OH $-$ $\to$ 2I $-$ + 2H2O + O2

Q25

Which one of the following reactions indicates the reducing ability of hydrogen peroxide in basic medium?

A HOCl + H2O2

\to

H3O+ + Cl

-

+ O2

B PbS + 4H2O2

\to

PbSO4 + 4H2O

C 2MnO

_4^ -

+ 3H2O2

\to

2MnO2 + 3O2 + 2H2O + 2OH

-

D Mn2+ + H2O2

\to

Mn4+ + 2OH

-

Correct Answer

Option C

Solution

$2 \mathrm{Mn}\overset{+7}{\mathrm{O}_{4}^{-}}+3 \mathrm{H}_{2} \mathrm{O}_{2} \rightarrow$ $2 \mathrm{Mn}\overset{+4}{\mathrm{O}_{2}}+3 \mathrm{O}_{2}+2 \mathrm{H}_{2} \mathrm{O}+2 \mathrm{O} \overline{\mathrm{H}}$ In basic medium $\mathrm{MnO}_{4}^{-}$ is reduced to $\mathrm{MnO}_{2}$ , whereas in acidic medium it is reduced to $\mathrm{Mn}^{+2}$ .

Q26

Consider the following reaction:

2HSO_4^ - (aq)\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{(2)\,Hydrolysis}^{(1)\,Electrolysis}} 2HSO_4^ - + 2{H^ + } + A

The dihedral angle in product A in its solid phase at 110 K is :

A 104

^\circ

B 111.5

^\circ

C 90.2

^\circ

D 111.0

^\circ

Correct Answer

Option C

Solution

A should be $\mathrm{H}_{2} \mathrm{O}_{2}$ Structure of $\mathrm{H}_{2} \mathrm{O}_{2}$ is solid phase Dihedral angle $=90.2^{\circ}$

Q27

The highest industrial consumption of molecular hydrogen is to produce compounds of element :

A Carbon

B Nitrogen

C Oxygen

D Chlorine

Correct Answer

Option B

Solution

Hydrogen combines with nitrogen to produce Ammonia in Haber's process.

$\mathrm{N}_{2}(\mathrm{g})+3 \mathrm{H}_{2}(\mathrm{g}) \rightleftharpoons 2 \mathrm{NH}_{3}(\mathrm{g})$ In this process, iron oxide is used with small amounts of $\mathrm{K}_{2} \mathrm{O}$ and $\mathrm{Al}_{2} \mathrm{O}_{3}$ to increase the rate of attainment of equilibrium.

Optimum conditions for the production of ammonia are a pressure of $200 \mathrm{~atm}$ and a temperature of $700 \mathrm{~K}$ .

Earlier, iron was used as a catalyst with molybdenum as a promoter in this reaction.

Q28

The metal salts formed during softening of hardwater using Clark's method are :

A

\mathrm{Ca}(\mathrm{OH})_{2}

and

\mathrm{Mg}(\mathrm{OH})_{2}

B

\mathrm{CaCO}_{3}

and

\mathrm{Mg}(\mathrm{OH})_{2}

C

\mathrm{Ca}(\mathrm{OH})_{2}

and

\mathrm{MgCO}_{3}

D

\mathrm{CaCO}_{3}

and

\mathrm{MgCO}_{3}

Correct Answer

Option B

Solution

In Clark's method, calculated amount of lime is added to hard water.

It precipitates out calcium carbonate and magnesium hydroxide which can filtered off.

\begin{aligned} &\mathrm{Ca}\left(\mathrm{HCO}_{3}\right)_{2}+\mathrm{Ca}(\mathrm{OH})_{2} \rightarrow 2 \mathrm{CaCO}_{3} \downarrow+2 \mathrm{H}_{2} \mathrm{O} \\\\ &\mathrm{Mg}\left(\mathrm{HCO}_{3}\right)_{2}+2 \mathrm{Ca}(\mathrm{OH})_{2} \rightarrow 2 \mathrm{CaCO}_{3} \downarrow+\mathrm{Mg}(\mathrm{OH})_{2}+2 \mathrm{H}_{2} \mathrm{O} \end{aligned}

Q29

Which of the given compounds can enhance the efficiency of hydrogen storage tank?

A SiH

_4

B Li/P

_4

C NaNi

_5

D Di-isobutylaluminium hydride

Correct Answer

Option C

Solution

Tanks of metal alloy like $\mathrm{NaNi}_{5}, \mathrm{Ti}{-\mathrm{TiH}_{2},} \mathrm{Mg}-{\mathrm{MgH}}_{2}$ are used for the storage of dihydrogen.

Q30

Which hydride among the following is less stable?

A NH

_3

B HF

C LiH

D BeH

_2

Correct Answer

Option D

Solution

The stability of hydrides depends on their bonding and the electronegativity difference between the elements.

The greater the electronegativity difference, the more stable the hydride.

Based on this, the order of stability of the given hydrides is: HF > NH

_3

> LiH > BeH

_2

Therefore, the less stable hydride among the given options is BeH

_2

.