Question 1

When potassium fluoride reacts with hydrofluoric acid to give KHF₂, which ionic species are present in the compound?

Accepted Answer

K⁺ and [HF₂]⁻. In the compound KHF₂, potassium (K⁺) acts as a cation while the anion is the bifluoride ion ([HF₂]⁻), which is formed from the interaction of hydrofluoric acid and fluoride ions, thus making option C the correct choice.

Question 2

In the sequence below, determine the species represented by x and y:
2H2SO4(aq) —electrolysis→ x —hydrolysis→ y + 2H+(aq) + H2O2(aq)

Accepted Answer

x = H2SO3SO3H(aq), y = H2SO4(aq). The correct option indicates that during the electrolysis of sulfuric acid (H2SO4), it is converted into a different species (H2SO3SO3H), which upon hydrolysis yields sulfuric acid (H2SO4) and other products. This reflects the chemical transformations occurring in the sequence.

Question 3

Which of the following methods can produce hydrogen of very high purity (99.9%)?

Accepted Answer

Electrolyzing water. Electrolyzing water separates hydrogen and oxygen through an electrical current, resulting in hydrogen that is highly pure, typically reaching purities of 99.9% or higher.

Question 4

An inorganic substance evolves oxygen on heating, makes an acidic potassium iodide solution turn violet, and decolourises acidified potassium permanganate. Which substance is it?

Accepted Answer

H2O2. H2O2, or hydrogen peroxide, decomposes upon heating to release oxygen, reacts with potassium iodide to form iodine which turns the solution violet, and reduces potassium permanganate, leading to its decolorization.

Question 5

Identify the incorrect statement about ortho and para hydrogen.

Accepted Answer

Ortho and para hydrogen differ in their chemical properties.. Ortho- and para-hydrogen have identical chemical properties and differ only in physical properties (boiling point, thermal conductivity), so 'they differ in chemical properties' (option 2) is the incorrect statement. The stored statement (normal H2 is an ortho/para blend) is true.

Question 6

With reference to hydrogen peroxide (H₂O₂), identify the statement that is not true:

Accepted Answer

It functions only as an oxidising agent.. Hydrogen peroxide is versatile and can act as both an oxidizing and a reducing agent, depending on the reaction conditions, making the statement incorrect.

Question 7

In the reaction below, determine x and y, and name the resulting gas mixture:
CH₄(g) + H₂O(g) —1270 K, Ni→ x + y

Accepted Answer

x = CO, y = H₂; syngas. The reaction involves methane and steam at high temperature, which typically produces carbon monoxide and hydrogen gas, known as syngas. This is a common process in gasification, where methane reacts with water to yield these two products.

Question 8

Which of the following statements about helium is not correct?

Accepted Answer

It is used to inflate balloons in place of hydrogen because it is lighter and does not catch fire.. Helium is denser (heavier) than hydrogen, not lighter; it is used in balloons because it is non-flammable, not because it is lighter. The other statements about superconducting magnets, cryogenics, and gas-cooled reactors are correct.

Question 9

Which of the following hydrogen bonds is strongest?

Accepted Answer

F−H···F. Fluorine is the most electronegative element, so the F-H...F hydrogen bond is the strongest of the listed options.

Question 10

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

Accepted Answer

Liquid hydrogen + liquid oxygen. Liquid hydrogen and liquid oxygen are commonly used as rocket propellants because they undergo a highly efficient combustion reaction, producing a large amount of thrust and water vapor as the only byproduct, making them both powerful and environmentally friendly.

Question 11

From the following statements regarding H2O2, choose the incorrect statement:
(1) It can act only as an oxidizing agent
(2) It decomposes on exposure to light
(3) It has to be stored in plastic or wax lined glass bottles in dark
(4) It has to be kept away from dust

Accepted Answer

It can act only as an oxidizing agent. Hydrogen peroxide (H2O2) can act as both an oxidizing agent and a reducing agent, making the statement that it can act only as an oxidizing agent incorrect.

Question 12

Which one of the following statements about water is FALSE ?
(1) Water is oxidized to oxygen during photosynthesis
(2) Water can act both as an acid and as a base
(3) There is extensive intramolecular hydrogen bonding in the condensed phase
(4) Ice formed by heavy water sinks in normal wat

Accepted Answer

There is extensive intramolecular hydrogen bonding in the condensed phase. The statement about extensive intramolecular hydrogen bonding in the condensed phase is incorrect because water primarily exhibits intermolecular hydrogen bonding, which is crucial for its unique properties, rather than significant intramolecular bonding.

Question 13

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]

Accepted Answer

3.4%. Volume strength 11.2 means molarity = 11.2/11.2 = 1 M. Strength = 1 * 34 = 34 g/L, i.e. 34 g per 1000 g (~1 L) solution = 3.4% w/v.

Question 14

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 hydrides.
(1) (a),

Accepted Answer

(a), (b), (c) and (d). (a) Saline (ionic) hydrides like NaH react with water to give H2. (b) 4BF3 + 3LiAlH4 -> 2B2H6 + 3LiF + 3AlF3. (c) PH3 has a lone pair (electron-rich); CH4 has exactly enough electrons (electron-precise). (d) HF and CH4 are molecular hydrides. All four are correct.

Question 15

The correct statements among (a) to (d) regarding H2 as a fuel are:
(a) It produces less pollutants than petrol.
(b) A cylinder of compressed dihydrogen weighs ~ 30 times more than a petrol tank producing the same amount of energy.
(c) Dihydrogen is stored in tanks of metal alloys like NaN

Accepted Answer

(a), (b) and (c) only. (a) H2 burns cleaner, (b) a compressed-H2 cylinder weighs ~30x a petrol tank for equal energy, and (c) H2 is stored in alloys like NaNi5 -- all true. (d) is false because the energy per gram values for liquid H2 (~142 kJ) and LPG (~50 kJ) are swapped. Correct set: (a),(b),(c).

Question 16

The equation that represents the water-gas shift reaction is:

Accepted Answer

CO(g) + H2O(g) 673K Catalyst CO2(g) + H2(g). The correct option accurately represents the water-gas shift reaction, where carbon monoxide reacts with water vapor to produce carbon dioxide and hydrogen gas, typically at elevated temperatures and in the presence of a catalyst.

Question 17

Among statement (a) – (d), the correct ones are:
(a) Decomposition of hydrogen peroxide gives dioxygen.
(b) Like hydrogen peroxide, compound, such as KClO3, Pb(NO3)2 and NaNO3 when heated liberate dioxygen.
(c) 2-Ethylanthraquinone is useful for the industrial preparation of hydrogen perox

Accepted Answer

(2) (a), (b), (c) and (d). All four statements are accurate: hydrogen peroxide decomposes to release dioxygen, compounds like KClO3 and others can also liberate dioxygen upon heating, 2-Ethylanthraquinone is indeed used in the industrial synthesis of hydrogen peroxide, and hydrogen peroxide is utilized in the production of sodium perborate.

Question 18

Hydrogen has three isotopes (A), (B) and (C). If the number of neutron(s) in (A), (B) and (C) respectively, are (x), (y) and (z), the sum of (x), (y) and (z) is:

Accepted Answer

3. Hydrogen's three isotopes have 0 (protium), 1 (deuterium) and 2 (tritium) neutrons. Their sum is 0 + 1 + 2 = 3.

Question 19

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:

Accepted Answer

(A), (B) and (D) only. Options (A), (B), and (D) are correct because hydrogen peroxide (H2O2) is indeed used in effluent treatment, can act as both an oxidizing and reducing agent, and is miscible with water. However, option (C) is incorrect as the two hydroxyl groups in H2O2 are not in the same plane due to the molecule's non-planar structure.

Question 20

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° and in solid phase is 111.5°.
Reason R: The change in dihedral angle in solid and gaseous phase is due to the difference in t

Accepted Answer

Both A and R are correct and R is the correct explanation of A.. The dihedral angle of H2O2 is 90.2 deg in the gas phase and 111.5 deg in the solid phase; both values are standard. The phase-dependent change arises because intermolecular forces (notably H-bonding in the solid) differ between phases, so R correctly explains A. Both A and R are correct and R IS the correct explanation.

Question 21

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

Accepted Answer

Both A and R are true and R is the correct explanation of A. The assertion is correct as hydrogen is indeed the most abundant element in the universe, while in the troposphere, nitrogen and oxygen are more prevalent gases. The reason is also true since hydrogen's lightness contributes to its tendency to rise and escape the troposphere, explaining why it is not the most abundant gas there.

Question 22

The correct statement about B2H6 is:
(1) Terminal B–H bonds have less p-character when compared to bridging bonds.
(2) The two B–H–B bonds are not of same length.
(3) All B–H–B angles are of 120°
(4) Its fragment, BH3, behaves as a Lewis base

Accepted Answer

(1). Terminal B–H bonds in B2H6 have a higher p-character compared to bridging bonds due to their different bonding environments; terminal bonds are more localized while bridging bonds involve more orbital overlap, leading to a difference in hybridization.

Question 23

Water does not produce CO on reacting with:

Accepted Answer

CO2. C, CH4 and C3H8 all react with steam to give CO (water-gas / steam reforming). CO2 with water does not produce CO, so the correct option is CO2.

Question 24

The number of non-ionisable hydrogen atoms present in the final product obtained from the hydrolysis of PCl5 is:
(1) 0 (2) 2 (3) 4 (4) 3

Accepted Answer

0. PCl5 + 4H2O -> H3PO4 + 5HCl. In H3PO4 = (HO)3P=O there is no P-H bond; all three H atoms are on -OH groups and are ionizable, so the number of non-ionizable H atoms is 0.

Question 25

Which of the following forms of hydrogen emits low energy β particles?
(1) Deuterium ²H
(2) Tritium ³H
(3) Protium ¹H
(4) Proton H⁺

Accepted Answer

Tritium ³H. Tritium (³H) is a radioactive isotope of hydrogen that undergoes beta decay, emitting low energy beta particles, while deuterium and protium are stable isotopes and do not emit beta particles.

Question 26

Deuterium resembles hydrogen in properties but:

Accepted Answer

reacts slower than hydrogen. Deuterium, being an isotope of hydrogen with an additional neutron, has a greater mass which affects its reaction kinetics, causing it to react more slowly than regular hydrogen in chemical reactions.

Question 27

Which one of the following statements is incorrect ? (1) Atomic hydrogen is produced when H2 molecules at a high temperature are irradiated with UV radiation. (2) At around 2000 K, the dissociation of dihydrogen into its atoms is nearly 8.1%. (3) Bond dissociation enthalpy of H2 is highest

Accepted Answer

At around 2000 K, the dissociation of dihydrogen into its atoms is nearly 8.1%.. The incorrect statement is (2): at about 2000 K the degree of dissociation of dihydrogen into atoms is only ~0.081%, not 8.1%. The other three statements (UV/arc gives atomic H; H2 has the highest single-bond dissociation enthalpy; Zn reacts with both HCl and NaOH to give H2) are all correct.

Question 28

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

Accepted Answer

(2) Nitrogen. Molecular hydrogen is primarily used in the Haber process to synthesize ammonia from nitrogen, which is essential for producing fertilizers and other nitrogen-containing compounds, making nitrogen the element with the highest industrial consumption of hydrogen.

Question 29

Which of the following can be used to prevent the decomposition of H2O2 ?

Accepted Answer

(1) Urea. Hydrogen peroxide is stabilized against decomposition by adding small amounts of stabilizers such as urea (also glycerol, acetanilide, sodium stannate/pyrophosphate). Among the options, urea is the correct stabilizer.

Question 30

The correct order of increasing intermolecular hydrogen bond strength is

Accepted Answer

CH4 < HCN < NH3. Hydrogen bonds are strongest in molecules where hydrogen is bonded to highly electronegative atoms like nitrogen. In this case, CH4 has no hydrogen bonding capability, HCN has moderate hydrogen bonding due to the presence of nitrogen, and NH3 has the strongest hydrogen bonds because of its ability to form multiple hydrogen bonds with surrounding molecules.

Question 31

Dihydrogen reacts with CuO to give

Accepted Answer

Cu. Dihydrogen reacts with copper(II) oxide (CuO) through a reduction process, where hydrogen reduces CuO to elemental copper (Cu) while itself being oxidized to water.

Question 32

Hydrogen has three isotopes: protium (¹H), deuterium (²H or D) and tritium (³H or T). They have nearly same chemical properties but different physical properties. They differ in
(1) Number of protons
(2) Atomic number
(3) Electronic configuration
(4) Atomic mass

Accepted Answer

Atomic mass. The isotopes of hydrogen differ in atomic mass because they have varying numbers of neutrons, which affects their overall mass while maintaining the same number of protons and electrons.

Question 33

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Hydrogen is an environment friendly fuel.
Reason R: Atomic number of hydrogen is 1 and it is very light element.
In the light of the above statements, choose the correct answer

Accepted Answer

Both A and R are true but R is NOT the correct explanation of A.. Hydrogen is indeed considered an environmentally friendly fuel because it produces only water when burned, making it a clean energy source. However, the atomic number and lightness of hydrogen do not directly explain its environmental benefits, which is why the reason provided does not serve as a correct explanation for the assertion.

Question 34

O–O bond length in H2O2 is X than the O–O bond length in F2O2. The O–H bond length in H2O2 is Y than that of the O–F bond in F2O2. Choose the correct option for X and Y from those given below

Accepted Answer

X-longer, Y-Shorter. The O–O bond in H2O2 is longer than in F2O2 due to the presence of steric hindrance and electron repulsion from the larger fluorine atoms, which shortens the O–F bond. Additionally, the O–H bond in H2O2 is shorter than the O–F bond in F2O2 because the electronegativity of fluorine pulls electron density away, resulting in a longer bond.

Question 35

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Physical properties of isotopes of hydrogen are different.
Reason R: Mass difference between isotopes of hydrogen is very large.
In the light of the above statements, choose t

Accepted Answer

Both A and R are true and R is the correct explanation of A. The assertion is correct because isotopes of hydrogen, such as protium, deuterium, and tritium, exhibit different physical properties due to their varying masses. The reason is also true, as the significant mass difference between these isotopes leads to observable variations in their physical properties, making it a valid explanation for the assertion.

Question 36

Given below are two statements:
Statement-I: Methane and steam passed over a heated Ni catalyst produces hydrogen gas.
Statement-II: Sodium nitrite reacts with NH4Cl to give H2O, N2 and NaCl.
In the light of the above statements, choose the most appropriate answer from the options given be

Accepted Answer

Both the statements I and II are correct. Both statements are accurate; Statement I describes the steam reforming process where methane reacts with steam over a nickel catalyst to produce hydrogen, while Statement II correctly outlines the reaction between sodium nitrite and ammonium chloride, resulting in water, nitrogen gas, and sodium chloride.

Question 37

Which hydride among the following is less stable ?

Accepted Answer

BeH2. BeH2 is less stable because it has a unique polymeric structure that leads to weaker bonding interactions compared to the other hydrides listed, making it more reactive and less stable under standard conditions.

Question 38

Match List I with List II.
List I
(Type of Hydride)
A. Electron deficient hydride
B. Electron rich hydride
C. Electron precise hydride
D. Saline hydride
List II
(Example)
I. MgH2
II. HF
III. B2H6
IV. CH4
Choose the correct answer from the options given below:

Accepted Answer

A-III, B-II, C-IV, D-I. The correct matches reflect the characteristics of each type of hydride: B2H6 is an electron deficient hydride due to its lack of sufficient electrons for bonding; HF is an electron rich hydride as it has a strong electronegative atom; CH4 is an electron precise hydride with a balanced electron count; and MgH2 is a saline hydride, which typically forms ionic bonds.

Question 39

’25 volume’ hydrogen peroxide means

Accepted Answer

1 L marketed solution contains 75 g of H2O2.. The term '25 volume' hydrogen peroxide indicates that 1 liter of the solution can release 25 liters of oxygen gas at standard conditions, which corresponds to a concentration of approximately 75 grams of H2O2 per liter.

Question 40

Lithium aluminium hydride can be prepared from the reaction of

Accepted Answer

LiH and Al2Cl6. Lithium aluminium hydride is synthesized through the reaction of lithium hydride with aluminium chloride, where lithium donates its hydride ions to aluminium, resulting in the formation of the desired compound.

Question 41

Given below are two statements: one is labeled as Assertion (A) and the other is labeled as Reason (R).
Assertion (A): PH3 has lower boiling point than NH3.
Reason (R): In liquid state NH3 molecules are associated through van der Waals' forces, but PH3 molecules are associated through hydr

Accepted Answer

(A) is correct but (R) is not correct.. PH3 has a lower boiling point than NH3 due to weaker van der Waals forces in PH3 compared to the strong hydrogen bonding in NH3, making the assertion true. However, the reason provided incorrectly states that PH3 is associated through hydrogen bonding, which is not the case, thus making the reason incorrect.

Question 42

On passing a gas, ‘X’, through Nessler’s reagent, a brown precipitate is obtained. The gas ‘X’ is

Accepted Answer

NH3. Nessler's reagent is specifically used to detect ammonia (NH3) in a solution, producing a brown precipitate when ammonia is present. This reaction is characteristic of ammonia, distinguishing it from the other gases listed.

Question 43

The correct statement/s about Hydrogen bonding is/are:
A. Hydrogen bonding exists when H is covalently bonded to the highly electro negative atom.
B. Intermolecular H bonding is present in o-nitro phenol
C. Intramolecular H bonding is present in HF.
D. The magnitude of H bonding depends on

Accepted Answer

(2) A, D, E only. A, D, E are correct. B is false because o-nitrophenol shows INTRAmolecular H-bonding (the chelate ring), and C is false because HF exhibits INTERmolecular H-bonding, not intramolecular. So the right set is A, D, E only.

Question 44

Given below are two statements:
Statement I: The increasing order of boiling point of hydrogen halides is HCl < HBr < HI < HF.
Statement II: The increasing order of melting point of hydrogen halides is HCl < HBr < HF < HI.
In the light of the above statements, choose the correct answer fro

Accepted Answer

(1) Both Statement I and Statement II are true. Both statements accurately reflect the trends in boiling and melting points of hydrogen halides. The boiling points increase due to the strength of hydrogen bonding and molecular weight, while the melting points are influenced by molecular structure and intermolecular forces.

Question 45

Which of the following could act as propellant for rockets?

Accepted Answer

Liquid hydrogen + liquid oxygen. Liquid hydrogen and liquid oxygen are commonly used as rocket propellants because they combine to produce a high-energy reaction, resulting in significant thrust and efficiency, making them ideal for space travel.

Question 46

Hydrogen bomb is based on the principle of

Accepted Answer

Nuclear fusion. A hydrogen bomb releases energy by the fusion of light nuclei (hydrogen isotopes) into heavier ones. The stored answer 'nuclear fission' is wrong; the correct principle is nuclear fusion.

Question 47

The correct order of the thermal stability of hydrogen halides (H − X) is

Accepted Answer

HF > HCl > HBr > HI. Thermal stability of hydrogen halides decreases down the group as bond strength weakens: HF>HCl>HBr>HI, option index 1, not the stored reverse order.

Question 48

Which of the following hydrogen bonds is the strongest?

Accepted Answer

F – H......F. Hydrogen-bond strength rises with the electronegativity of the atoms involved, and fluorine is the most electronegative element. Therefore F-H...F is the strongest hydrogen bond, stronger than any O-H...O or O-H...F bond.

Question 49

Regarding the industrial manufacture of hydrogen from water gas (a mixture of CO and H2), which statement is correct?

Accepted Answer

CO is first converted to CO2 by reaction with steam in the presence of a catalyst, and the CO2 is then absorbed in alkali. This option is correct because it describes the water-gas shift reaction, where carbon monoxide reacts with steam to produce carbon dioxide and hydrogen. The subsequent absorption of CO2 in alkali effectively removes it from the gas mixture, allowing for the purification of hydrogen.

Question 50

The numbers of protons, electrons and neutrons in a molecule of heavy water are respectively:

Accepted Answer

10, 10, 10. D2O: two deuterium atoms give 2 protons, 2 neutrons, 2 electrons; oxygen-16 gives 8 protons, 8 neutrons, 8 electrons. Totals are 10 protons, 10 electrons, 10 neutrons.

JEE Main Chemistry: Hydrogen questions with solutions

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