MCQ Questions for Class 11 Chemistry Chapter 9 Hydrogen with Answers

Answer: (b) DiOxygen
Explanation:
When sodium peroxide dissolves in water:
2Na₂O₂ + 2H₂O → 4NaOH + O₂

Answer: (c) Neutrons
Explanation:
Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom.

Answer: (c) Ni
Explanation:
Steam reforming of natural gas is the most common method of producing commercial bulk hydrogen at about 95% of the world production of 500 billion m3 in 1998, or 70 million tonnes by 2018.Hydrogen is used in the industrial synthesis of ammonia and other chemicals. At high temperatures (700 – 1100°C) and in the presence of a metal-based catalyst (nickel), steam reacts with methane to yield carbon monoxide and hydrogen.
CH₄ + H₂O ⇌ CO + 3 H₂

Answer: (c) Hydrogen
Explanation:
Henry Cavendish FRS was an English natural philosopher, scientist, and an important experimental and theoretical chemist and physicist. He is noted for his discovery of hydrogen, which he termed “inflammable air”. He described the density of inflammable air, which formed water on combustion, in a 1766 paper, On Factitious Airs. Antoine Lavoisier later reproduced Cavendishs experiment and gave the element its name.

Answer: (b) Zn
Explanation:
When a base reacts with a metal salt in hydrogen gas is formed. In this reaction metal is zinc & base is Sodium hydroxide. When sodium hydroxide solution is heated with zinc granules then Sodium zincate and hydrogen gas are formed.
2NaOH (aq) + Zn(s) → Na₂ZnO₂ (aq)+ H₂(g)
The salt formed by the reaction between a base and a metal, the metal is present as a part of the Negative ion. In the sodium zincate salt (Na₂ZnO₂) formed by the reaction between Sodium Hydroxide and Zinc metal, the zinc metal is present at a part of a negative ions , zincate ion (ZnO₂^-2 ) All the metals do not react with bases to form salt and hydrogen gas. The main product formed in this reaction is sodium zincate (Na₂ZnO₂)

Answer: (a) Nascent Molecular Hydrogen
Explanation:
The hydrogen set free at the time of its preparation from its compounds is also in atom from and is commonly known nascent hydrogen. The newly born hydrogen is in atomic form that is why it is called nascent hydrogen.

Answer: (b) Pt
Explanation:
Glycerol, phosphoric acid or acetanilide is added to H₂O₂ to check its decomposition.

Answer: (a) 0 to 4 °C
Explanation:
Water show a wide range of anomalies compared to similar liquids or hydrides of other group 16 elements. One of the most talked-about anomalies is the formation of ice from liquid water and how the density changes when we cool the water.

O is a small atom and highly electronegative compared to Hydrogen. So O attracts the covalent clouds of O-H towards itself, thus making water a polar molecule. The hydrogen bonding in water molecules causes high boiling point and liquid state compared to other hydrides of group 16.

When we cool water from higher temperature, the density steadily decreases. At 4 degree C it is the highest. But below 4 degree C, The H-bonds break between the molecules and the molecules get drifted further apart, the volume increases and density decreases. The crystalline form of water is ice. At atmospheric pressure ice crystallises in the hexagonal form, but at very low temperatures it condenses to cubic form leaving gap between the structures, thus increasing the volume again.

Density of ice is less than that of water. Therefore, an ice cube floats on water. In winter season ice formed on the surface of a lake provides thermal insulation which ensures the survival of the aquatic life.

Answer: (b) Copper and HCl(aq)
Explanation:
Copper is a noble metal. As it lies below hydrogen in the electrochemical series. Therefore it cant displace hydrogen from dilute HCl. While iron and sodium lie above hydrogen in the electrochemical series. so they can liberate H₂ either from steam or H₂SO₄ solution.
Fe + H2SO₄ ↔ FeSO₄ + H₂
3Fe + 4H₂O (steam) ↔ Fe₃O₄ + 4H₂
Cu + HCl(g) → No reaction
2Na + 2C₂H₅OH → 2C₂H₅ONa + H₂

Answer: (a) Beta-Emitting
Explanation:
Tritium is a beta-emitting radioactive isotope of hydrogen. Its nucleus consists of one proton and two neutrons, making it three times as heavy as a hydrogen nucleus (with its one proton) and one-and-a-half times as heavy as deuterium (which contains one proton and only one neutron).

Answer: (a) 1.0 g / cm³
Explanation:
Water never has an absolute density because its density varies with temperature. Water has its maximum density of 1 g/cm³ at 4 degrees Celsius. When the temperature changes from either greater or less than 4 degrees, the density will become less then 1 g/cm³. Water has the maximum density of 1 g/cm³ only when it is pure water. Other factors affect waters density such as whether it is tap or fresh water or salt water. These variations of water changes its density because whats in the water has its own density.

Answer: (a) CO
Explanation:
Water gas is a combustion fuel containing carbon monoxide (CO) and hydrogen gas (H₂). Water gas is made by passing steam over heated hydrocarbons.

Answer: (b) 224 ml
Explanation:
2H₂O₂ → 2H₂O + O₂
2 × 34 g = 22400 ml
As 2 × 34 g = 68 g of H₂O₂ liberates
22400 ml O₂ at STP
Therefore, 0.68 g of H₂O₂ liberates
= (0.68 × 22400)/(68) = 224 ml

Answer: (d) All of the above
Explanation:
H₂O₂ show all these properties

Answer: (c) Black Suspension of Lead Sulphide(PbS)
Explanation:
Lead sulphide (black suspension) on reaction with hydrogen peroxide forms lead sulphate and water. Lead sulphate as well as water are colourless, therefore lead sulphite decolourises on addition of hydrogen peroxide.
PbS(s) + 4H₂O₂ (aq) → PbSO₄ (s) + 4H₂O (aq)

Answer: (a) 1
Explanation:
The maximum number of electrons present in a shell is given by the formula 2n², where “n” is the orbit number or energy level index, 1, 2, 3 , …… Hence the maximum number of electrons in different shells are as follows:
First orbit or K-shell will be = 2 × 12 = 2
Hydrogen (H), lithium (Li), and sodium (Na), all have one electron in their outermost shells. This means that they can achieve a stable configuration and a filled outer shell by donating or losing an electron.

Answer: (c) Blue
Explanation:
This is due to the formation of CrO5
K₂Cr₂O₇ + H₂SO₄ + 4H₂O₂ → K₂SO₄ + 2CrO₅ + 5H₂O
So it is Blue

Answer: (b) Multiple
Explanation:
In a sample of hydrogen gas, the number of hydrogen molecules is present. These molecules dissociate and produce hydrogen atoms when heated. Each hydrogen atom contains one electron. The hydrogen atoms absorb different amounts of energy and go to different excited states. From there, they take different paths and come back to ground state. Since different paths are associated with different energies, different spectral lines are formed in the spectrum.

Answer: (b) 90%
Explanation:
H₂O₂ is used as an oxidant for rocket fuel. Usually, 90% concentration of H₂O₂ is used.

Answer: (c) 4
Explanation:
Hydrogen has three main isotopes; Protium (¹H), deuterium (²H) and tritium (³H). These isotopes form naturally in nature. Protium and deuterium are stable. Tritium is radioactive and has a half-life of about 12 years. Scientists have created four other hydrogen isotopes (4H to 7H), but these isotopes are very unstable and do not exist naturally.
The main isotopes of hydrogen are unique because they are the only isotopes that have a name.