Q.1 Which is the most abundant element in the universe?
Oxygen
Hydrogen
Carbon
Helium
Explanation - Hydrogen constitutes about 75% of the elemental mass of the universe, making it the most abundant element.
Correct answer is: Hydrogen
Q.2 What is the usual oxidation state of hydrogen in its compounds with non-metals?
+1
0
-1
+2
Explanation - Hydrogen typically exhibits +1 oxidation state when bonded with non-metals, such as in H2O and HCl.
Correct answer is: +1
Q.3 Hydrogen forms a hydride with sodium. What type of hydride is NaH?
Ionic hydride
Covalent hydride
Metallic hydride
Complex hydride
Explanation - NaH is formed by a reaction of hydrogen with a highly electropositive metal (sodium), producing an ionic hydride.
Correct answer is: Ionic hydride
Q.4 Which hydrogen isotope is radioactive?
Protium
Deuterium
Tritium
None of these
Explanation - Tritium (³H) is radioactive with a half-life of about 12.3 years, while protium and deuterium are stable.
Correct answer is: Tritium
Q.5 The bond in H2 molecule is
Ionic
Covalent
Metallic
Hydrogen bond
Explanation - H2 consists of two hydrogen atoms sharing a pair of electrons, forming a single covalent bond.
Correct answer is: Covalent
Q.6 Which method is commonly used for laboratory preparation of hydrogen?
Electrolysis of water
Reaction of acids with metals
Both A and B
Thermal decomposition of CO2
Explanation - Hydrogen can be prepared in the lab by electrolysis of water or by reacting metals like zinc with dilute acids.
Correct answer is: Both A and B
Q.7 Hydrogen is insoluble in water because it is
Non-polar
Highly reactive
Ionic
Polar
Explanation - Hydrogen (H2) is a non-polar molecule and does not interact strongly with polar water molecules, making it poorly soluble.
Correct answer is: Non-polar
Q.8 Which is used as rocket fuel due to high energy content of hydrogen?
H2O
H2
NH3
CH4
Explanation - Hydrogen gas has a very high enthalpy of combustion, making it ideal as a rocket fuel.
Correct answer is: H2
Q.9 The reaction of hydrogen with nitrogen at high temperature and pressure produces
NH3
N2H4
NO2
NH4NO3
Explanation - Hydrogen reacts with nitrogen in the Haber process under high pressure and temperature to form ammonia (NH3).
Correct answer is: NH3
Q.10 Which of the following is true about hydrogen bonding?
Occurs between H and O, N, or F
Occurs in H2 molecule
Is ionic in nature
Does not exist in water
Explanation - Hydrogen bonding occurs when hydrogen is covalently bonded to electronegative atoms like O, N, or F and interacts with lone pairs of another electronegative atom.
Correct answer is: Occurs between H and O, N, or F
Q.11 What is the standard electrode potential of H+/H2 half-cell?
0 V
+1.0 V
-0.44 V
+0.77 V
Explanation - By definition, the standard hydrogen electrode (SHE) has a potential of 0 V.
Correct answer is: 0 V
Q.12 Which is the lightest element?
Helium
Hydrogen
Lithium
Beryllium
Explanation - Hydrogen has an atomic number 1 and atomic mass 1, making it the lightest element.
Correct answer is: Hydrogen
Q.13 Which catalyst is commonly used in the hydrogenation of vegetable oils?
Platinum
Nickel
Copper
Iron
Explanation - Nickel acts as a catalyst in the hydrogenation of unsaturated fats to convert them into saturated fats.
Correct answer is: Nickel
Q.14 Which of the following statements is correct about hydrogen molecule?
It is paramagnetic
It is diamagnetic
It has ionic bond
It is metallic
Explanation - H2 has all electrons paired in its molecular orbital, making it diamagnetic.
Correct answer is: It is diamagnetic
Q.15 Hydrogen chloride in aqueous solution shows
Acidic nature
Basic nature
Neutral nature
Amphoteric nature
Explanation - HCl dissociates completely in water to produce H+ ions, showing acidic properties.
Correct answer is: Acidic nature
Q.16 Which of the following is a use of heavy water (D2O)?
Nuclear reactor moderator
Rocket fuel
Solvent in HPLC
Cleaning agent
Explanation - Deuterium oxide (D2O) is used as a moderator in nuclear reactors to slow down neutrons.
Correct answer is: Nuclear reactor moderator
Q.17 Which of the following is a proton donor according to Brønsted–Lowry theory?
H2
HCl
NaOH
CH4
Explanation - HCl donates a proton (H+) in aqueous solution, acting as a Brønsted–Lowry acid.
Correct answer is: HCl
Q.18 The H-H bond length in hydrogen molecule is approximately
0.74 Å
1.0 Å
0.5 Å
1.5 Å
Explanation - Experimental measurements show the H-H bond length is about 0.74 Å.
Correct answer is: 0.74 Å
Q.19 Which of the following hydrides is covalent in nature?
CH4
NaH
CaH2
LiH
Explanation - CH4 consists of hydrogen covalently bonded to carbon, forming a covalent hydride.
Correct answer is: CH4
Q.20 Tritium is used in
Radioactive tracing
Fuel cells
Water purification
Hydrogenation of oils
Explanation - Tritium is radioactive and is used as a tracer in biochemical and environmental studies.
Correct answer is: Radioactive tracing
Q.21 Which of the following represents the Haber process?
N2 + 3H2 → 2NH3
2H2 + O2 → 2H2O
CH4 + 2O2 → CO2 + 2H2O
H2 + Cl2 → 2HCl
Explanation - The Haber process synthesizes ammonia by reacting nitrogen and hydrogen under high temperature and pressure with a catalyst.
Correct answer is: N2 + 3H2 → 2NH3
Q.22 Hydrogen can act as a reducing agent. Which reaction demonstrates this?
CuO + H2 → Cu + H2O
H2 + O2 → H2O
CH4 + Cl2 → CH3Cl + HCl
HCl + NaOH → NaCl + H2O
Explanation - Hydrogen reduces copper(II) oxide to copper while itself being oxidized to water.
Correct answer is: CuO + H2 → Cu + H2O
Q.23 Which of the following is NOT a property of hydrogen?
Colorless
Odorless
Highly soluble in water
Lightest element
Explanation - Hydrogen is poorly soluble in water due to its non-polar nature.
Correct answer is: Highly soluble in water
Q.24 Which form of hydrogen has one proton and one neutron in its nucleus?
Protium
Deuterium
Tritium
None of these
Explanation - Deuterium (²H) has one proton and one neutron in the nucleus, making it a stable isotope of hydrogen.
Correct answer is: Deuterium