Chemistry (Part-V) (Railway)

Total Questions: 50

21. The conversion of ethanol to ethanoic acid is an example of which of the following reaction? [RRB Group 'D' CBT Exam, 22.08.2022 (Shift-III)]

(1) Combustion reaction
(2) Addition reaction
(3) Oxidation reaction
(4) Substitution reaction

Correct Answer: (3) Oxidation reaction

Solution:The conversion of ethanol to ethanoic acid is an oxidation reaction.

• The oxidation reaction is a process in which oxygen is gained, or hydrogen is lost.

• The addition of an oxygen atom to ethanol produces ethanoic acid.

• Since the hydrogen atom is removed and oxygen is added, ethanol is transformed to ethanoic acid, which is an oxidation process.

22. In the given reaction,__________ acts as a reducing agent. [RRB Group 'D' CBT Exam, 22.08.2022 (Shift-III)]

Fe₂O₃ + 3CO → 2Fe + 3CO₂

(1) Fe
(2) CO₂
(3) Fe₂O₃
(4) CO

Correct Answer: (3) Fe₂O₃

Solution:Reducing agents are those substances which reduce other substances (addition of hydrogen or removal of oxygen) and themselves get oxidised (addition of oxygen or removal of hydrogen).

In the reaction, Fe₂O₃ + 3CO → 2Fe + 3CO₂, Carbon monoxide (CO) acts as a reducing agent as it reduces Ferric (III) oxide (Fe₂O₃) to form Iron (Fe) and Carbon dioxide (CO₂).

23. What is the correct order of metallic character of the following metals? [RRB Group 'D' CBT Exam, 22.08.2022 (Shift-III)]

(1) Na < Mg < Cs < Ba
(2) Cs < Ba < Na < Mg
(3) Mg < Na < Ba < Cs
(4) Ba < Cs < Mg < Na

Correct Answer: (3) Mg < Na < Ba < Cs

Solution:Correct order of metallic character of the following metals Mg < Na < Ba < Cs

24. Consider the below statements and identify the correct answer. [RRB Group 'D' CBT Exam, 22.08.2022 (Shift-III)]

Statement I: Ionic compounds are generally brittle and break into pieces when pressure is applied.

Statement II: Ionic compounds have low melting and boiling points.

(1) Both the statements are true.
(2) Statement-II is true, and Statement-I is false.
(3) Both the statement are false.
(4) Statement-I is true, and Statement-II is false.

Correct Answer: (4) Statement-I is true, and Statement-II is false.

Solution:Ionic compounds are brittle due to the strong bond between the positive and negative ions that make up the molecules.

• These positive and negative bonds create crystals in rigid, lattice structures. Applying pressure shifts the alignment of the ions and results in brittleness.

• Ionic compounds have high melting and boiling points.

• As the ionic lattice contains such a large number of ions, a lot of energy is needed to overcome this ionic bonding so ionic compounds have high melting and boiling points.

25. Consider the statements given below and identify the correct answer. [RRB Group 'D' CBT Exam, 22.08.2022 (Shift-III)]

Statement I: Washing soda is produced from sodium chloride.

Statement II: It attacks dirt and grease to form water soluble products, which are then washed away on rinsing with water.

(1) Both the statements are true.
(2) Statement-II is true, and Statement-I is false.
(3) Both the statements are false.
(4) Statement-I is true, and Statement-II is false.

Correct Answer: (2) Statement-II is true, and Statement-I is false.

Solution:Washing soda (Na₂CO₃), also known as sodium carbonate.

• It has detergent properties or cleansing properties because it can remove dirt and grease from dirty clothes, etc.

• It attacks dirt and grease to form water-soluble products, which are then washed away on rinsing with water.

26. Which of the following triads is NOT a Dobereiner's triad? [RRB Group 'D' CBT Exam, 22.08.2022 (Shift-III)]

(i) Li, Na, K

(ii) Ca, Sr, Ba

(iii) N, P, Sb

(iv) Cl, Br, I

(1) Only iii
(2) Only i
(3) Only ii
(4) Only iv

Correct Answer: (1) Only iii

Solution:According to Dobereiner's law of triads, the arithmetic mean of the atomic masses of the first and third element in a triad would be approximately equal to the atomic mass of the second element in that triad.

• Atomic masses of Nitrogen (N), Phosphorus (P) and antimony (Sb) are 14.01, 30.97 and 121.76 respectively.

• Hence, they do not follow Dobereiner 's triad.

27. In the reaction ZnO + C → Zn + CO: [RRB Group 'D' CBT Exam, 22.08.2022 (Shift-III)]

(1) ZnO is reduced to Zn
(2) Zn does not undergo redox reaction.
(3) ZnO is oxidized to Zn
(4) Carbon is reduced to CO

Correct Answer: (1) ZnO is reduced to Zn

Solution:Adding oxygen to material and removing hydrogen from a substance is known as an oxidation reaction.

• In the reaction ZnO + C → Zn + CO, the addition of oxygen causes the oxidation of C to CO.

• Because oxygen is eliminated, ZnO is reduced to Zn.

28. The insoluble substance formed in a solution during a chemical reaction is known as _______. [RRB Group 'D' CBT Exam, 23.08.2022 (Shift-I)]

(1) soluble salt
(2) aqueous solution
(3) residue
(4) precipitate

Correct Answer: (4) precipitate

Solution:Precipitation is a chemical process in which two ions bind together to produce an insoluble salt known as the precipitate in an aqueous solution.

• Silver chloride is a classic example of a precipitation reaction in aqueous solution.

• The precipitation of a white solid is noticed when silver nitrate is introduced to a potassium chloride solution.

• AgNO₃ + KCI → AgCl (↓) + KNO₃

29. Consider the below statements and identify the correct answer. [RRB Group 'D' CBT Exam, 23,08.2022 (Shift-I)]

Statement-I: Most carbon compounds are poor conductors of electricity.

Statement II: Carbon compounds have low melting and boiling points.

(1) Both the statements are true
(2) Both the statements are false.
(3) Statement-II is true, and Statement-I is false
(4) Statement-I is true, and Statement-II is false.

Correct Answer: (1) Both the statements are true

Solution:Carbon compounds are covalent in nature. Covalent compounds do not dissociate into ions in aqueous solution and also it does not have free electrons.

• Since there is no flow of charge, carbon compounds are poor conductors of electricity

• Carbon compounds have usually low melting points and boiling points because they are covalent in nature.

• Covalent compounds have Vander Waal force of attraction between the molecules which low melting points and boiling points.

30. Consider the statements below and identify the correct answer. [RRB Group 'D' CBT Exam, 23.08.2022 (Shift-I)]

Statement- I: Modern periodic table has 18 vertical columns known as groups.

Statement-II: Modern periodic table has 7 horizontal rows known as periods.

(1) Both statements are incorrect
(2) Both statements are correct.
(3) Statement II is correct. statement I is incorrect.
(4) Statemente I is correct. statement II is incorrect.

Correct Answer: (2) Both statements are correct.

Solution:The vertical columns in the modern periodic table are known as groups and the horizontal rows are known as periods.

• There are 7 periods and 18 groups in the modern periodic table.

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