Hydrogen MCQ Quiz - Objective Question with Answer for Hydrogen - Download Free PDF

CONCEPT:

Nascent Hydrogen

• Nascent hydrogen refers to the freshly generated hydrogen atoms, which are highly reactive and can participate in various chemical reactions.
• In an alkaline medium, certain metal pairs can produce nascent hydrogen by undergoing redox reactions.
• These metals must have suitable standard electrode potentials to facilitate the production of nascent hydrogen in an alkaline environment.

EXPLANATION:

• In an alkaline medium, the production of nascent hydrogen involves the reaction of metals with water or hydroxide ions (OH^-).
• The relevant reactions are:
  • Zn + 2OH^- → ZnO₂^2- + H₂
  • Al + 3OH^- → Al(OH)₄^- + 3H
• In the given options:
  • Option 1: Zn and Al can produce nascent hydrogen in an alkaline medium due to their suitable electrode potentials.
  • Option 2: Fe and Ni do not readily produce nascent hydrogen in an alkaline medium.
  • Option 3: Al and Mg can produce nascent hydrogen, but Mg is more reactive in acidic mediums.
  • Option 4: Mg and Zn can also produce nascent hydrogen, but the combination of Zn and Al is more commonly referenced for this reaction.

Therefore, the metal-pair that can produce nascent hydrogen in an alkaline medium is Zn and Al (Option 1).

EXPLANATION:

Isotopes of Hydrogen

• Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number.
• Hydrogen has three main isotopes:
  • Protium (1^H): It has 1 proton and 0 neutrons.
  • Deuterium (2^H or D): It has 1 proton and 1 neutron.
  • Tritium (3^H or T): It has 1 proton and 2 neutrons.
• Among these, the correct answer is:
  • Dubnium (2): It is not an isotope of hydrogen.
  • Dubnium is a chemical element with the symbol Db and atomic number 105, which is entirely different from hydrogen.

Therefore, Dubnium is not an isotope of hydrogen.

CONCEPT:

Ionic Hydrides and Their Reaction with Water

• Ionic hydrides are compounds formed between hydrogen and the alkali or alkaline earth metals.
• These hydrides contain the hydride ion (H^-), which is a hydrogen atom with an extra electron.
• When ionic hydrides react with water, the hydride ion (H^-) acts as a strong base and reacts with water to form hydrogen gas (H₂) and hydroxide ions (OH^-).

EXPLANATION:

• When an ionic hydride, such as sodium hydride (NaH), reacts with water, the reaction can be represented as:

  NaH + H₂O → NaOH + H₂

  • The hydride ion (H^-) reacts with water to produce hydroxide ions (OH^-), which makes the solution basic.
  • Hydrogen gas (H₂) is also released as a byproduct of the reaction.
• This reaction demonstrates that the solution becomes basic due to the formation of hydroxide ions (OH^-).

Therefore, the correct answer is option 3, as ionic hydrides react with water to give basic solutions.

CONCEPT:

Energy Levels in a Hydrogen Atom

• In a hydrogen atom, the energy of an electron is determined solely by its principal quantum number (n).
• Electrons in orbitals with the same principal quantum number have the same energy, regardless of their angular momentum quantum number (l).

EXPLANATION:

• The hydrogen atom is unique in that it has only one electron and no electron-electron interactions.
• This makes the energy of its orbitals dependent only on the principal quantum number (n).
• For n=3, the orbitals 3s, 3p, and 3d all have the same energy because they all share the same principal quantum number (n=3).

Therefore, the correct statement is: 3s, 3p, and 3d orbitals all have the same energy in a hydrogen atom.

CONCEPT:

Structure of Hydrogen Peroxide (H₂O₂)

• Hydrogen peroxide has a non-planar, non-linear structure.
• The molecule is characterized by a "twisted" (skewed) structure, resembling an open book.
• The O-O bond is single, and the H-O-O-H dihedral angle is approximately 111.5 degrees.

EXPLANATION:

Hydrogen peroxide (H2O2) is a non-planar molecule with twisted symmetrical structure. It has non-linear structure with an open book structure. 

• H₂O₂ adopts a non-planar shape due to the repulsion between electron pairs on the oxygen atoms.
• The molecule is not linear because the hydrogen atoms are positioned at an angle relative to the oxygen-oxygen bond.

Therefore, the structure of H₂O₂ is non-planar, non-linear.

The correct answer is Na2CO3.

Key Points

• The sodium compound is used for softening hard water. Washing soda or sodium carbonate is used for removing the permanent hardness of the water.
• Washing soda has a chemical formula Na₂CO₃.10H2O.
• It binds calcium and magnesium molecules in water.
• Water can be softened by adding sodium carbonate (washing soda) or bypassing the water through an ion-exchange column.
• For large-scale municipal operations, a process known as the lime-soda process is used to remove Ca²⁺ and Mg²⁺ from the water supply.
•  

Additional Information

The correct answer is A reducing agent.

Key Points

• Hydrogen peroxide H₂O₂ is acting as a reducing agent here.
• A reducing agent is a compound that oxidises itself and reduces the other compound in a chemical reaction.
• A reducing agent will lose electrons in a chemical reaction, and thus get oxidized.
• Here, the charge on Chlorine (Cl) is earlier 0, but after reaction, the charge on each Cl atom is -1, this shows that it has been reduced. Thus, Hydrogen peroxide has worked as a reducing agent.
• Also, in terms of hydrogen, adding hydrogen is termed as reduction, whereas removing it is termed as oxidation. Since hydrogen is added to chlorine, chlorine is reducing, and hence we can say that Hydrogen peroxide has worked as a reducing agent.

The correct answer is Colourless.

Explanation:

• Hydrogen is the most abundant gas in the universe.
• The chemical element hydrogen has the symbol H and the atomic number 1.
• It is the very first element in the periodic table.
• The hydrogen nucleus contains one proton but no neutron.
• It is insoluble in water and lighter than the air.
• In nature, hydrogen gas is colourless, odourless, non-toxic, and tasteless.
• It is a combustible gas, but it does not support combustion

Thus, the colour of the hydrogen gas is colourless.

The correct answer is option 3, i.e., CO + H₂.

• The mixture of CO (carbon monoxide) and H₂ (hydrogen gas) is known as 'water gas'.
• Since this mixture is used in the synthesis of methanol and many hydrocarbons, it is also known as 'syngas'.
• Reaction of steam on hydrocarbons or coke at high temperature in the presence of a catalyst (like Nickel) yields syngas.

• It is a method of preparation of hydrogen gas.
• When the syngas is produced from coal, the process is termed as 'coal gasification'.

C (s) + H₂O (g)  CO (g) + H₂ (g)

• The production of hydrogen gas can be increased by reacting carbon monoxide of syngas mixture with steam in the presence of iron chromate catalyst.
• This reaction is termed as 'water-gas shift reaction'.

CO + H2O (g)  CO₂ (g) + H2 (g)

• Carbon dioxide produced is removed by scrubbing with sodium arsenite solution.

The correct answer is option 3,i.e. Tritium.

• Tritium is the radioactive isotopes of hydrogen.
• Hydrogen is a colourless, odourless, tasteless, flammable gasesous substance.
• A single hydrogen atom has one proton and one electron.
• One of two or more species of atoms of a chemical element with same atomic number but the different mass number is known as isotopes.  
• Three isotopes of hydrogen are found in nature:
  • Protium has no neutron.
  • Deuterium has 1 neutron.
  • Tritium has 2 neutrons.
• Deuterium is used to make heavy water(D2O).
• Heavy water used in nuclear reactors as a neutron moderator.

• Heavy water is not radioactive.
• Hence, option 2 is incorrect.
• Heavy Water:-​
  • Deuterium oxide, D2O.
  • It is an oxide of the isotope of hydrogen, Deuterium.
  • It is a colourless and odourless liquid.
  • A molecule of heavy water has two deuterium atoms in place of the two normal hydrogen atoms of ordinary "light" water.
  • The presence of deuterium gives the water different nuclear properties, and the increase of mass gives it slightly different physical and chemical properties when compared to normal water.
  • Heavy water is not radioactive.
  • Heavy water is not safe to drink. 
  • American scientist and Nobel laureate Harold Urey discovered the isotope deuterium in 1931.
  • Argentina is the main producer of heavy water.
  • Heavy water is used in certain types of nuclear reactors, where it acts as a neutron moderator to slow down neutrons so that they are more likely to react with the fissile uranium-235 than with uranium-238. ​

Non-stoichiometric hydrides or Metallic Hydrides are hydrogen deficient.

• This means that they don’t hold the Law of Constant Composition.
• Hydrides of Nickel, Palladium, Cerium, and Actinium occupy the interstitial position in the lattice.
• This allows a large amount of hydrogen absorption.
• Metals like Palladium and Platinum can store large amounts of hydrogen and hence are used for the same.

The correct answer is Zinc.

Key Points

• Hydrogen gas can be easily prepared in the laboratory.
• This preparation of hydrogen gas usually involves the action of dilute sulphuric acid or dilute hydrochloric acid on zinc granules.
• Granulated zinc is ideal for the preparation of hydrogen gas in chemical laboratories because it usually contains a small amount of copper, which has the ability to act as a catalyst to the associated chemical reaction and, therefore, increase the rate of the chemical reaction without actually participating in it.
• The chemical reaction that takes place in formation of Hydrogen gas is
  • Zn + H₂SO₄ → ZnSO₄ + H₂ 
• Uses of Hydrogen gas:
  • It is used to fill many balloons and airships.
  • It is also used for the hardening of animal oils and certain vegetable oils.
  • It is widely used as a fuel in oxy-hydrogen blow pipes.

Additional Information

• Uses of Copper:
  • Electrical wiring
  • Roofing
  • Plumbing
  • Industrial machinery
• Uses of Helium:
  • Airbags
  • Cleaning rocket fuel-tank
  • Arc welding
  • Medicine and Scientific research
• Uses of Mercury:
  • Electrical and electronic equipment
  • Industrial chemicals

The correct answer is Hydrogen Carbonates.

Key Points

• Temporary hardness is due to the presence of Calcium hydrogen carbonate Ca(HCO₃)₂(aq) and Magnesium hydrogen carbonate Mg(HCO₃)₂(aq).
• The hydrogen carbonates of both Calcium and Magnesium decompose upon heating.
• The original insoluble carbonate is reformed when water is boiled.
• The following is the precipitation reaction -
  • Ca(HCO₃)_2(aq) → CO₂(g) + H₂O(l) + CaCO₃
  • Mg(HCO₃)₂(aq)→CO₂(g) + H₂O(l) + MgCO₃
• Boiling of water results in the removal of Magnesium and Calcium ions from water, and thus its hardness.
• This is the reason why it is called temporary hardness.

The correct answer is option 3, i.e. Hydrogen ions.

• Acids and Bases exhibit their conducting property only if they are in aqueous solution in which they could completely ionize in water.
• As per Arrhenius' concept, acids are those that produce the hydrogen ion (H+) when dissolved in water.
• Bases produce the hydroxide ion(OH-) when dissolved in water
• These ions, when in water, act as charge carriers and can hence conduct electricity.
• The pH level is a measure of the number of Hydrogen ions in a solution.
• The lower the solution or compound on the pH scale, the higher will be the concentration of hydrogen ions.