Hydrogen Questions — JEE Chemistry

Q1

The water having more dissolved O2 is :

A boiling water

B water at 80

^\circ

C

C polluted water

D water at 4

^\circ

C

Correct Answer

Option D

Solution

On heating concentration of O2 in water decreases. So boiling water and water at 80

^\circ

C having less O2 concentration. Polluted water also having less O2 concentration. So water at 4

^\circ

C having maximum O2 concentration.

Q2

Which of the following can be used to prevent the decomposition of

\mathrm{H}_{2} \mathrm{O}_{2}

?

A Urea

B Formaldehyde

C Formic acid

D Ethanol

Correct Answer

Option A

Solution

Urea is used as a stabilizer for the storage of

\mathrm{H}_{2} \mathrm{O}_{2}

.

Q3

The normal rain water is slightly acidic and its

\mathrm{pH}

value is

5.6

because of which one of the following?

A

\mathrm{N}_{2} \mathrm{O}_{5}+\mathrm{H}_{2} \mathrm{O} \rightarrow 2 \mathrm{HNO}_{3}

B

2 \mathrm{SO}_{2}+\mathrm{O}_{2}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow 2 \mathrm{H}_{2} \mathrm{SO}_{4}

C

4 \mathrm{NO}_{2}+\mathrm{O}_{2}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow 4 \mathrm{HNO}_{3}

D

\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{H}_{2} \mathrm{CO}_{3}

Correct Answer

Option D

Solution

Normally rain water has a pH of 5.6 due to presence of H+ ions formed by the reaction of rain water with carbon dioxide present in the atmosphere.

\begin{aligned} & \mathrm{H}_2 \mathrm{O}(\mathrm{l})+\mathrm{CO}_2(\mathrm{~g}) \leftrightharpoons \mathrm{H}_2 \mathrm{CO}_3(\mathrm{aq}) \\\\ & \mathrm{H}_2 \mathrm{CO}_3(\mathrm{aq}) \leftrightharpoons \mathrm{H}^{+}(\mathrm{aq})+\mathrm{HCO}_3^{-}(\mathrm{aq}) \end{aligned}

Q4

The isotopes of hydrogen are :

A Tritium and protium only

B Protium and Deuterium only

C Protium, deuterium and tritium

D Deuterium and tritium only

Correct Answer

Option C

Solution

Isotopes of hydrogen are (1) Protium (1H1) (2) Deuterium (1H2) (3) Tritium (1H3)

Q5

The synonym for water gas when used in the production of methanol is :

A fuel gas

B laughing gas

C syn gas

D natural gas

Correct Answer

Option C

Solution

H2O(g) + C $\to$ CO + H2 The gaseous mixture CO + H2 which is produced when steam is passed over red hot coke and this mixture called water gas or synthesis gas or syn gas.

Q6

The correct statements among (a) to (d) are : (a) saline hydrides produce H2 gas when reacted with H2O. (b) reaction of LiAlH4 with BF3 leads to B2H6. (c) PH3 and CH4 are electron - rich and electron - precise hydrides, respectively. (d) HF and CH4 are called as molecular

A (a), (b), (c) and (d)

B (a), (c) and (d) only

C (c) and (d) only

D (a), (b) and (c) only

Correct Answer

Option A

Solution

(a) NaH + H2O $\to$ NaOH + H2 (b) 3LiAlH4 + 4BF3 $\to$ 2B2H6 + 3LiF + 3AlF3 (c) PH3 is electron rich due to one lone pair while CH4 is electron precise hydride. (d) HF and CH4 are molecular hydrides.

Q7

The strength of 11.2 volume solution of H2O2 is : [Given that molar mass of H = 1 g mol–1 and O = 16 g mol–1]

A 3.4%

B 34%

C 13.6%

D 1.7%

Correct Answer

Option A

Solution

Strength means

{{Weight} \over {Volume}}

%. Molarity of H2O2 =

{{volume\,strength} \over {11.2}}

=

{{11.2} \over {11.2}}

= 1 M = 34 gm/lit In 1000 ml solution 34 gm H2O2 present $\therefore$ In 100 ml solution 3.4 gm H2O2 present.

Q8

Which of the following equation depicts the oxidizing nature of H2O2?

A

C{l_2} + {H_2}{O_2} \to 2HCl + {O_2}

B

KI{O_4} + {H_2}{O_2} \to KI{O_3} + {H_2}O + {O_2}

C

2{I^ - } + {H_2}{O_2} + 2{H^ + } \to {I_2} + 2{H_2}O

D

{I_2} + {H_2}{O_2} + 2O{H^ - } \to 2{I^ - } + 2{H_2}O + {O_2}

Correct Answer

Option C

Solution

2{I^ - } + {H_2}{O_2} + 2{H^ + } \to {I_2} + 2{H_2}O

Oxygen reduces from –1 to –2.

So, its reduction will takes place.

Hence it will behave as oxidising agent or it shows oxidising nature.

While in other option it change from (–1) to 0.

Q9

Statements about heavy water are given below : A. Heavy water is used in exchange reactions for the study of reaction mechanisms. B. Heavy water is prepared by exhaustive electrolysis of water. (C) Heavy water has higher boiling point than ordinary water. (D) Viscosity of H2O is greater than D2O. Choose the most appropriate answer from the options given below :

A A, B, and C only

B A and C only

C A and D only

D A and B only

Correct Answer

Option A

Solution

Viscosity of D2O is greater than H2O. B.P. of D2O is greater than H2O.

Q10

Which of the following could act as a propellant for rockets?

A Liquid oxygen + liquid argon

B Liquid hydrogen + liquid oxygen

C Liquid nitrogen + liquid oxygen

D Liquid hydrogen + liquid nitrogen

Correct Answer

Option B

Solution

Liquid hydrogen and liquid oxygen are used as excellent fuel for rockets.

{H_2}\left( \ell \right)

has low mass and high enthalpy of combustion whereas oxygen is a strong supporter of combustion.