Chemistry (Part-IV) (Railway)

Total Questions: 50

21. There are three isotopes of hydrogen atom, namely Protium Deuterium and Tritium. The respective atomic number and mass number of the isotope Tritium is: [RRB NTPC CBT-1 Exam, 13.03.2021 (Shift-I)]

(1) 1,1
(2) 1.2
(3) 1,3
(4) 3,1

Correct Answer: (3) 1,3

Solution:Those elements which have the same atomic number but a different mass number are called Isotopes. There are three isotopes of hydrogen namely, protium, ₁H¹, deuterium, ₁H² or D and lastly tritium, ₁H³ or T.

Tritium comprises 2 neutrons and 1 proton in its nucleus.
The atomic number of tritium is 1 and atomic mass of 3.

22. ________ is a sulphur containing amino acid. [RRB NTPC CBT-1 Exam, 15.03.2021 (Shift-I)]

(1) Serine
(2) Tryptophan
(3) Histidine
(4) Cysteine

Correct Answer: (4) Cysteine

Solution:Cysteine is a sulfur-containing amino acid. It is a non-essential amino acid important for making protein and for other metabolic functions. It is found in beta-keratin.

23. Whish of the following element has maximum density? [RRB NTPC CBT-1 Exam, 15.03.2021 (Shift-I)]

(1) Platinum
(2) Osmium
(3) Mercury
(4) Lead

Correct Answer: (2) Osmium

Solution:Osmium is the densest naturally occurring element, with an experimentally measured (using x-ray crystallography) density of 22.65 g/cm³.

The very small atomic radius of osmium results in a small metal-metal separation.
This small atomic separation along with osmium's relatively high atomic number gives rise to osmium's high density.

24. Which of the following is an example of man-made fiber? [RRB NTPC CBT-1 Exam, 01.04.2021 (Shift-I)]

(1) Rayon
(2) Silk
(3) Linen
(4) Jute

Correct Answer: (1) Rayon

Solution:Manmade fibers are made from various chemicals, or are regenerated from plant fibers.

Rayon is a man-made fiber prepared from cellulose by chemical treatment.
The cellulose required for making rayon is obtained from wood pulp. Rayon is obtained by the chemical treatment of wood pulp.

25. To neutralise the effect of forming acid injected by ant bite, which among the following can be used? [RRB NTPC CBT-1 Exam, 01.04.2021 (Shift-I)]

(1) Potassium carbonate
(2) Calcium carbonate
(3) Sodium bicarbonate
(4) Sodium carbonate

Correct Answer: (3) Sodium bicarbonate

Solution:A paste of sodium hydrogen carbonate (sodium bicarbonate) is used to relieve the pain of an ant bite.

Baking soda contains alkaline compounds that will help to neutralize skin's pH balance.
This reduce inflammation round the affected area.
This helps to alleviate soreness as well as itchiness.

26. Which factor(s) led scientists towards the classification of elements? [RRB Group 'D' CBT Exam, 17.08.2022 (Shift-II)]

(i) Different methods of synthesis of elements

(ii) Different source of elements

(iii) Different properties of el-ements

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

Correct Answer: (2) Only ii

Solution:The method of grouping the elements into different classes is known as the peri-odic classification of elements.

Classification helps us to understand the properties of the elements and their compounds.
Based on their position in the periodic table one can predict the properties of the elements and their compounds.
It is easier to study, compare, and differentiate the properties of the elements and compounds from different groups.

27. When chlorination of dry slaked lime takes place, _________ will form as the main product. [RRB Group 'D' CBT Exam, 17.08.2022 (Shift-II)]

(1) hydrochloric acid
(2) calcium oxychloride
(3) quicklime
(4) acetic acid

Correct Answer: (2) calcium oxychloride

Solution:When chlorine is passed over dry slaked lime, it results in the formation of bleaching powder or Calcium oxychloride.

Chlorine gas is produced from the chlor-alkali process.
Ca(OH)2 + Cl₂ → CaOCl₂ + H₂O

28. Study the given diagram, carefully. Which option correctly explains the reason for the appearance of the blue black colour? [RRB Group 'D' CBT Exam, 17.08.2022 (Shift-II)]

(1) Potato juice contains proteins, which turn blue black with iodine
(2) Potato juice contains starch, which turns blue black with iodine.
(3) Potato juice contains glucose, which turns blue black with iodine.
(4) Potato juice contains fats, which turn blue black with iodine.

Correct Answer: (2) Potato juice contains starch, which turns blue black with iodine.

Solution:Raw potato contains approximately 17% starch.

Iodine solution is used to test the presence of starch in food materials.
When iodine solution is added to the raw potato sample, it turns blue-black. Iodine reacts with the starch present in the raw potato which results in the formation of a blue-black coloured complex.

29. Which of the following elements has the maximum number of atoms in their molecular form? [RRB Group 'D' CBT Exam, 17.08.2022 (Shift-II)]

(1) S
(2) P
(3) Аг
(4) Ne

Correct Answer: (1) S

Solution:S-8

P-4

Ne - 1

Ar - 1

30. Cyclohexane contains ____ C-C bonds and _ C-H bonds, so total ___ covalent bonds. [RRB Group 'D' CBT Exam, 17.08.2022 (Shift-II)]

(1) 4, 8, 12
(2) 4, 12, 16
(3) 6, 10, 16
(4) 6, 12, 18

Correct Answer: (4) 6, 12, 18

Solution:Cyclohexane is a simple ring structure having 6 carbon atoms with the chemical formula of CH₁₂.

It has six carbon-carbon single bonds and twelve carbon-hydrogen single bonds.
Therefore, there are 18 covalent bonds in one molecule of cyclohexane.

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