Railway Science (Chemistry-Miscellaneous) (Part-III)

Total Questions: 27

21. Which of the following can undergo sublimation ? [RRB ALP Tier - I (20/08/2018) Evening]

Correct Answer: (a) Ammonium chloride
Solution:

Ammonium chloride (NH₄Cl) - Sal ammoniac, the salt of ammonia and hydrogen chloride; A by-product of sodium carbonate. Sublimation - The process by which the solid directly changes into gaseous form skipping the middle phase of being liquid. Ammonium sulphide - (NH₄)₂S, Ammonium chlorate - NH₄ClO₃ , Ammonium sulphate - (NH₄)₂SO₄ .

22. The state of matter can be changed into another state by changing the: [RRB ALP Tier - I (30/08/2018) Morning]

Correct Answer: (b) Temperature
Solution:

Three states of matter: Solid (definite shape and volume), liquid (definite volume), and gas (No definite shape or volume). A matter changes state when energy is either given to it or taken away from it. Example: Solids on heating changes to liquid, liquid on further heating changes to gases.

23. Which one of the following elements is polyatomic ? [RRB ALP Tier - I (30/08/2018) Afternoon]

Correct Answer: (a) Sulphur
Solution:

Molecules - A group of two or more atoms held together by attractive forces known as chemical bonds. Molecule type based on number of atoms : Diatomic Molecules - These molecules consist of two atoms of the same element bonded together. Examples- oxygen (O₂), nitrogen (N₂), etc.
Triatomic Molecules - It contains three atoms. Example- carbon dioxide (CO₂). Polyatomic Molecules - They are composed of more than three atoms. Example - Ammonia (NH₃), Water (H₂O), etc.

24. Which of the following statements is/are correct or incorrect? [RRB ALP Tier - I (30/08/2018) Afternoon]

Statements :
A) The rotation of Earth is responsible for wind blowing.
B) A fuel would be regarded as environment friendly if its combustion products were non- poisonous.
C) Coal is a complex mixture of compounds of 𝑂₂𝐻² and half free carbon.
A small amount of Nitrogen and Sulphur compounds are also present in coal.

Correct Answer: (c) Only statement B is correct, statement A and C are incorrect
Solution:

Only statement B is correct, statement A and C are incorrect. Air pressure and unequal heating of earth are the factors responsible for wind blowing. Coal is a complex mixture of compounds primarily composed of Carbon (C), Hydrogen (H), and Oxygen (O), along with smaller amounts of Nitrogen (N) and Sulfur (S) compounds.

25. What is the compound formed when Ag⁺ and Cl-combine ? [RRB ALP Tier - I (30/08/2018) Evening]

Correct Answer: (c) Silver Chloride
Solution:

It is a white crystalline chemical compound. It is prepared when sodium chloride is added to silver nitrate solution a white precipitate of silver chloride occurs. Silver (Ag), atomic number - 47. Group - 11. Chlorine (Cl), atomic number - 17. Group - 17.

26. Which of the following is NOT a constituent of biogas ? [RRB ALP Tier - I (31/08/2018) Morning]

Correct Answer: (b) Carbon Monoxide
Solution:

Biogas is produced through a biochemical process in which certain types of bacteria convert the biological wastes into useful bio-gas.
Biogas is produced through anaerobic decomposition of biomass. The major constituent of biogas is Methane (55-75%), CO₂ (30-45%) and some traces of gases such as H₂S and Ammonia.

27. Which of the following statements is/are true or false? Statements: [RRB ALP Tier - I (31/08/2018) Evening]

Statements:
(A) H₂SO₄ is used in the refining of petroleum to remove sulphur and other compounds.
(B) The basic nature of Sodium Hydroxide (NaOH) is due to the presence of Hydrogen ions in the solution.

Correct Answer: (d) Only statement A is true
Solution:

In the refining of petroleum, H₂SO₄ (sulfuric acid) is used as a catalyst in a process called "sweetening" or "desulfurization" to remove sulfur and other sulfur-containing compounds.
It involves the following steps - Contact with Petroleum, Reaction (Sulfuric acid reacts with the sulfur-containing compounds in the petroleum), Separation (removes the sulfur compounds from the petroleum stream) and Regeneration (sulfuric acid, now containing the extracted sulfur compounds, is regenerated by treating it with an oxidizing agent, such as air or hydrogen peroxide).