CHEMISTRY (Part-VI) (Railway)

Total Questions: 50

41. Which of the following elements has valency 3? [RRB Group 'D' CBT Exam, 30.08.2022 (Shift-I)]

(1) Al
(2) S
(3) C
(4) Mg

Correct Answer: (1) Al

Solution:

Valence electrons are the total number of electrons present in the outermost shell of an element.
Aluminium (Al) with atomic number of 13 has the electronic configuration of 1s² 2s² 2p⁶ 3s² 3p¹.

● So it has 3 valence electrons in outermost cell.

42. When soidum sulphide reacts with dilute hydrocholiric acid. a gas with unpleasant smell is produced. This gas with unpleasant smell is: [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

(1) H₂S
(2) SO₃
(3) SO₂
(4) H₂

Correct Answer: (1) H₂S

Solution:

Hydrogen Sulphide (H₂S) gas is produced when dilute hydrochloric acid reacts with sodium sulphide.

● Na₂S + 2HCl → 2NaCl + H₂S

43. Identify the basic reuirements that led scientists towards the classificiation of elements. [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

(i) Identification of some pattern in different properties of elements

(ii) Rearrangement of ele-ments on the basis of their synthesis

(iii) to get overall idea of the colour of different elements.

(1) (i) and (iii)
(2) only (i)
(3) (ii) and (iii)
(4) (i), (ii) and (iii)

Correct Answer: (2) only (i)

Solution:

Scientists attempted classification of elements to understand the properties of the elements and their compounds.

● They wanted to identify some patterns in different properties of elements based on their position in the periodic table.

● They aimed to study, compare, and differentiate the properties of the elements and compounds from different groups.

44. CuSO₄ + Mg → MgSO₄ + Cu In the above reaction Mg is the [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

(1) oxidising agent
(2) dissolving agent
(3) reducing agent
(4) catalyst

Correct Answer: (3) reducing agent

Solution:

When magnesium is added to blue copper (II) sulphate solution, the blue colour fades as colourless magnesium sulphate is formed and brown bits of copper metal form a precipitate.

● It is a redox reaction resulting in displacement of copper by magnesium.

● Magnesium acts as a reducing agent here.

45. The balanced reaction for the following chemical rection is: [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

Hydroen + Bromine → Hydrogen bromide

(1) H₂ + Br₂ → 2HBr
(2) H₂+2Br→ 2HBг
(3) 2H+ Br₂→ 2HBг
(4) H+ Br→ НВг

Correct Answer: (1) H₂ + Br₂ → 2HBr

Solution:

Hydrogen gas and bromine gas react to form Hydrogen bromide.

● H₂ + Br₂ → 2HBr

● It is a synthesis reaction.

46. Which of the following is the chemical reaction involved in the baking soda preparation? [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

(1) NaHCO₃ + H⁺ → CO₂ + H₂O + Sodium salt of acid
(2) NaCl + H₂O + CO₂ + NH₃ → NH₄Cl + NaHCO₃
(3) Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O
(4) 2NaCl(aq) + 2H₂O(l) → 2NaOH (aq) + Cl₂ (g) + H₂ (g)

Correct Answer: (2) NaCl + H₂O + CO₂ + NH₃ → NH₄Cl + NaHCO₃

Solution:

Sodium bicarbonate (NaHCO₃), also known as Sodium Hydrogen Carbonate, is also known as baking soda.

● It is made by saturating a solution of sodium carbonate with carbon dioxide.

● The white crystalline powder of sodium hydrogen carbonate being less soluble, gets separated out.

● NaCl + H₂O + CO₂ + NH₃ → NH₄Cl + NaHCO₃

47. The catenation property shown by carbon refers to which of the following properties ? [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

(1) Self-combining capacity to form a long chain of atoms
(2) Property of occurring as different allotropes
(3) Self-degeneration property
(4) Property of carbon to give combustive nature t its compounds

Correct Answer: (1) Self-combining capacity to form a long chain of atoms

Solution:Catenation is a property by which a carbon atom can bond with any number of other carbon atoms to form straight chains, branched chains and rings of various sizes.

● The high tendency of carbon to catenate is because of high C-C bond strength.

48. Identify the correct order if A, B, C, D, E are the atomic numbers of the elements in positions of rows 1 to 4 of the periodic table of Groups 15, 16, 17 respectively, as specified in figure below [RRB Group 'D' CBT Exam. 01.09.2022 (Shift-I)]

Group 15	Group 16	Group 17
A	C	–
–	–	–
–	–	–
B	D	E

(1) B > D > E > A > C
(2) E > B > D > A > C
(3) A > B > C > D > E
(4) D > B > E > C > A

Correct Answer: (4) D > B > E > C > A

Solution:

Group 15	Group 16	Group 17
7 N (A)	8 O (C)	9 F
15 P	16 S	17 Cl
33 As	34 Se	35 Br (E)
51 Sb (B)	52 Te (D)	53 I

Hence, Increasing order of A, B, C, D and E are:
D > B > E > C > A

49. Which among the following is NOT a use of sodium hydroxide? [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

(1) Used in making soaps and detergents.

(ii) Used in the manufacture of paper.

(iii) Used for removing permanent hardness of water.

(1) Only iii
(2) Only ii
(3) Both ii and iii
(4) Only i

Correct Answer: (1) Only iii

Solution:

Washing Soda (Na₂CO₃-10H₂O) is a natural cleaner and a powerful water softener that is used for removing permanent hardness of water.

● It is an inorganic hydrate of sodium carbonate.

● It is a salt of carbonic acid.

50. What is the waste product in photosynthesis? [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-III)]

(1) Water
(2) Oxygen
(3) Glucose
(4) Carbon dioxide

Correct Answer: (2) Oxygen

Solution:

Photosynthesis is the process by which green plants make their own food from carbon dioxide and water in the presence of sunlight.

● To prepare one molecule of glucose, by the process of photosynthesis six molecules of carbon dioxide and six molecules of water is required.

● Oxygen molecule and water is released as a waste product.

● This oxygen is produced due to splitting of water by the process of photolysis during light reaction.

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CHEMISTRY (Part-VI) (Railway)

41. Which of the following elements has valency 3? [RRB Group 'D' CBT Exam, 30.08.2022 (Shift-I)]

42. When soidum sulphide reacts with dilute hydrocholiric acid. a gas with unpleasant smell is produced. This gas with unpleasant smell is: [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

43. Identify the basic reuirements that led scientists towards the classificiation of elements. [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

44. CuSO₄ + Mg → MgSO₄ + Cu In the above reaction Mg is the [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

45. The balanced reaction for the following chemical rection is: [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

46. Which of the following is the chemical reaction involved in the baking soda preparation? [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

47. The catenation property shown by carbon refers to which of the following properties ? [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

48. Identify the correct order if A, B, C, D, E are the atomic numbers of the elements in positions of rows 1 to 4 of the periodic table of Groups 15, 16, 17 respectively, as specified in figure below [RRB Group 'D' CBT Exam. 01.09.2022 (Shift-I)]

49. Which among the following is NOT a use of sodium hydroxide? [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-I)]

50. What is the waste product in photosynthesis? [RRB Group 'D' CBT Exam, 01.09.2022 (Shift-III)]

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