Hydrogen — Page 5 | NEET Chemistry

Q41

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Heavy water is used for the study of reaction mechanism. Reason (R) : The rate of reaction for the cleavage of O - H bond is slower than that of O - D bond. Choose the most appropriate answer from the options given below :

A Both (A) and (R) are true but (R) is not the true explanation of (A).

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

C (A) is false but (R) is true.

D (A) is true but (R) is false.

Correct Answer

Option D

Solution

D2O in used for the study of reaction mechanism. Rate of reaction for the cleavage of O-H bond > O-D bond.

Q42

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Loss of electron from hydrogen atom results in nucleus of

\sim 1.5 \times 10^{-3} \mathrm{pm}

size. Reason R : Proton

\left(\mathrm{H}^{+}\right)

always exists in combined form. In the light of the above statements, choose the most appropriate answer from the options given below:

A Both

\mathbf{A}

and

\mathbf{R}

are correct and

\mathbf{R}

is the correct explanation of

\mathbf{A}

B A is correct but R is not correct

C A is not correct but R is correct

D Both

\mathbf{A}

and

\mathbf{R}

are correct but

\mathbf{R}

is NOT the correct explanation of

\mathbf{A}

Correct Answer

Option D

Solution

Size of nucleus is of order $1.5 \times 10^{-15} \mathrm{~m}$ or $1.5 \times 10^{-3} \mathrm{pm}$ $\mathrm{H}^{+}$ always exists in combined form.

There is no relation between two statements and hence option (D) is the answer.

Q43

Given below are two statements : Statement I : H2O2 can act as both oxidising and reducing agent in basic medium. Statement II : In the hydrogen economy, the energy is transmitted in the form of dihydrogen. In the light of the above statements, choose the correct answer from the options given below :

A Both statement I and statement II are false

B Statement I is false but statement II is true

C Statement I is true but statement II is false

D Both statement I and statement II are true

Correct Answer

Option D

Solution

Oxidising action in basic medium 2Fe2+ + H2O2 $\to$ 2Fe3+ + 2OH– Reducing action in basic medium I2 + H2O2 + 2OH– $\to$ 2I– + 2H2O + O2 Advantage of hydrogen economy is that energy is transmitted in the form of dihydrogen and not as electric power

Q44

Match List I with List II .tg .tg List I List II A. Cobalt catalyst I.

\mathrm{(H_2+Cl_2)}

production B. Syngas II. Water gas production C. Nickel catalyst III. Coal gasification D. Brine solution IV. Methanol production Choose the correct answer from the options given below :

A A-IV, B-III, C-I, D-II

B A-IV, B-III, C-II, D-I

C A-II, B-III, C-IV, D-I

D A-IV, B-I, C-II, D-III

Correct Answer

Option B

Solution

(A) Hydrogen reacts with carbon monoxide in presence of cobalt catalyst to give methanol

2 \mathrm{H}_{2}(\mathrm{~g})+\mathrm{CO}(\mathrm{g}) \stackrel{\text{ cobalt catalyst }}{\longrightarrow} \mathrm{CH}_{3} \mathrm{OH}(\mathrm{I})

(B) Syn gas is produced from coal and the process is called coal gasification.

\mathrm{C}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \stackrel{1270 \mathrm{~K}}{\longrightarrow} \underset{(\text{ syn gas) }}{\mathrm{CO}(\mathrm{g})+\mathrm{H}_{2}(\mathrm{~g})}

(C) Reaction of steam with hydrocarbons or coke at high temperature in presence of nickel catalyst gives a mixture of $\mathrm{CO}$ and $\mathrm{H}_{2}$ , called water gas

\mathrm{CH}_{4}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \underset{{\mathrm{Ni}}}{\stackrel{1270 \mathrm{~K}}{\longrightarrow}}\underset{(\text{ water gas })}{\mathrm{CO}(\mathrm{g})+3 \mathrm{H}_{2}(\mathrm{~g})}

(D) Electrolysis of brine solution produces $\mathrm{H}_{2}$ gas at cathode and $\mathrm{Cl}_{2}$ gas at anode $\mathrm{NaCl}(\mathrm{aq}) \longrightarrow \mathrm{Na}^{+}(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq})$ Cathode : $2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})+2 \mathrm{e}^{-} \longrightarrow \mathrm{H}_{2}(\mathrm{~g})+2 \mathrm{OH}^{-}(\mathrm{aq})$ Anode : $2 \mathrm{Cl}^{-}(\mathrm{aq}) \longrightarrow \mathrm{Cl}_{2}(\mathrm{~g})+2 \mathrm{e}^{-}$

Q45

The INCORRECT statement(s) about heavy water is (are) (A) used as a moderator in nuclear reactor (B) obtained as a by-product in fertilizer industry (C) used for the study of reaction mechanism (D) has a higher dielectric constant than water Choose the correct answer from the options given below :

A (D) only

B (B) and (D) only

C (B) only

D (C) only

Correct Answer

Option A

Solution

Heavy water (D2O) is obtained as a by-product in the fertilizer industry.

It is used as a moderator in nuclear reactors and for the study of the reaction mechanisms.

Its dielectric constant is lower than that of H2O.

Q46

Given below are two reactions, involved in the commercial production of dihydrogen (H

_2

). The two reactions are carried out at temperature "T

_1

" and "T

_2

", respectively

C(s) + {H_2}O(g)\overset{{{T_1}}}\longrightarrow CO(g) + {H_2}(g)

CO(g) + {H_2}O(g)\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{Catalyst}^{{T_2}}} C{O_2}(g) + {H_2}(g)

The temperatures T

_1

and T

_2

are correctly related as :

A T

_1

< T

_2

B T

_1

= T

_2

C T

_1

= 100 K, T

_2

= 1270 K

D T

_1

> T

_2

Correct Answer

Option D

Solution

These reactions are part of the water-gas shift reaction used in the industrial production of hydrogen.

The first reaction is the endothermic steam reforming of coal (carbon), while the second reaction is the exothermic water-gas shift reaction.

Carbon reacts with steam at high temperatures (around 1000°C or 1273 K) to form carbon monoxide and hydrogen: C(s) + H $_2$ O(g) $\xrightarrow[T_1]{}$ CO(g) + H $_2$ (g) Then carbon monoxide reacts with steam in the presence of a catalyst to produce carbon dioxide and more hydrogen: CO(g) + H $_2$ O(g) $\xrightarrow[Catalyst]{[T_2]}$ CO $_2$ (g) + H $_2$ (g) Since the first reaction is endothermic (absorbs heat), it requires a higher temperature to proceed than the second reaction, which is exothermic (releases heat).

Therefore, the temperature T $_1$ should be higher than T $_2$ .

Q47

Given below are two statements : One is labelled as Assertion A and other is labelled as Reason R. Assertion A : The dihedral angles in H2O2 in gaseous phase is 90.2

^\circ

and in solid phase is 111.5

^\circ

. Reason R : The change in dihedral angle in solid and gaseous phase is due to the difference in the intermolecular forces. Choose the most appropriate answer from the options given below for A and R.

A A is correct but R is not correct.

B Both A and R are correct but R is not the correct explanation of A.

C Both A and R are correct and R is the correct explanation of A.

D A is not correct but R is correct.

Correct Answer

Option D

Solution

(a) H2O2 structure in gas phase, dihedral angle is 111.5°. (b) H2O2 structure in solid phase at 110K, dihedral angle is 90.2° Hence given statement (A) is not correct.

But statement (B) is correct.

Q48

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Isotopes of hydrogen have almost same chemical properties, but difference in their rates of reaction. Reason R : Isotopes of hydrogen have different enthalpy of bond dissociation. In the light of the above statements, choose the most appropriate answer from the options given below:

A A is not correct but R is correct

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

C A is correct but R is not correct

D Both A and R are correct and R is the correct explanation of A

Correct Answer

Option D

Solution

Assertion A : Isotopes of hydrogen (protium, deuterium, and tritium) have almost the same chemical properties because they have the same number of protons and electrons, which dictate chemical behavior.

However, they differ in their rates of reaction due to differences in their atomic masses, which affect reaction kinetics.

Reason R : The isotopes of hydrogen have different enthalpy of bond dissociation due to their differences in atomic mass.

The stronger bond in deuterium compared to protium, for example, leads to higher bond dissociation enthalpy.

This, in turn, influences the rate of reactions involving these isotopes, as breaking the bonds requires different amounts of energy.

Therefore, the correct answer is Both A and R are correct, and R is the correct explanation of A.

Q49

Which of the following statements in relation to the hydrogen atom is correct?

A 3s orbital is lower in energy than 3p orbital

B 3p orbital is lower in energy than 3d orbital

C 3s and 3p orbitals are of lower energy than 3d orbital

D 3s, 3p and 3d orbitals all have the same energy

Correct Answer

Option D

Solution

NOTE : In one electron species, such as

H

-atom, the energy of orbital depends only on the principal quantum number,

n.

Hence answer

(d)

i.e.

is

2s = 2p < 3s = 3p = 3d < 4s = 4p = 4d = 4f

Q50

The correct statements about H2O2 are : (A) used in the treatment of effluents. (B) used as both oxidising and reducing agents. (C) the two hydroxyl groups lie in the same plane. (D) miscible with water. Choose the correct answer from the options given below :

A (A), (C) and (D) only

B (A), (B), (C) and (D)

C (A), (B) and (D) only

D (B), (C) and (D) only

Correct Answer

Option C

Solution

H2O2 act as both oxidising and reducing agent.

H2O2 is miscible with water due to open book like structure both -OH group are not in the same plane H2O2 used in the treatment of effluents.