CHEMISTRY (Part-III) (Railway)

41. What is the symbol of tungston? [RRB RPF Constable Exam, 25.01.2019 Shift-I]

(1) Tn
(2) Tu
(3) Tg
(4) W

Correct Answer: (4) W

Solution:Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74.

• It has the highest melting point and highest tensile strength of any element.

42. Nucleon is made up of ______. [RRB RPF Constable Exam, 25.01.2019 Shift-III]

(1) Electron only
(2) Proton and Neutron
(3) Valence Electrons
(4) Nucleus and proton

Correct Answer: (2) Proton and Neutron

Solution:Nucleon is the collective term for protons and neutrons.

• Nucleons are the particles found in the nucleus of atoms.

• Each atomic nucleus includes one or more nucleons.

43. An heterogeneous mixture in which the solute particles are not decomposed, but remain suspended throughout the medium, are called _______. [RRB RPF Constable Exam, 25.01.2019 Shift-III]

(1) Emulsification
(2) Convection
(3) Suspension
(4) Osmosis

Correct Answer: (3) Suspension

Solution:Non-homogeneous systems, in which solids are dispersed in liquids, are called suspension.

• A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Particles of a suspension are visible to the naked eye.

44. Which of the following is called 'lead sugar'? [RRB RPF Constable Exam, 11.02.2019 Shift-I]

(1) Lead Carbonate
(2) Lead Dioxide
(3) Lead Oxide
(4) Lead Acetate

Correct Answer: (4) Lead Acetate

Solution:Lead acetate is also known as lead sugar. It is a white crystalline chemical compound with a sweetish taste.

It is made by treating lead oxide with acetic acid.
It is highly toxic and is soluble in water.

45. _______ is an acid in which an atom of oxygen is connected to an atom of hydrogen and at least one other element. [RRB RPF Constable Exam, 11.02.2019 Shift-I]

(1) Oxyacid
(2) Oxoacid
(3) Hydroacid
(4) Hydrecid

Correct Answer: (1) Oxyacid

Solution:An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen.

• Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce the H and the anion of the acid.

46. Which gas is emitted by the reaction of chloroform and HNO₃? [RRB RPF Constable Exam, 11.02.2019 Shift-I]

(1) Tear gas
(2) Methyl isocyanate
(3) Chloropicrin
(4) Lewisite

Correct Answer: (3) Chloropicrin

Solution:Chloroform and HNO₃ react to produce CCI₃NO₂ which is also known as chloropicrin.

HNO₃ + CHCI₃ → CCI₃NO₂ + H₂O

• Chloropicrin is used in agriculture as a soil fumigant

47. Electro valent compounds are usually soluble in _______. [RRB RPF Constable Exam, 15.02.2019 Shift-I]

(1) Diesel
(2) Kerosene
(3) Water
(4) Petrol

Correct Answer: (3) Water

Solution:Electrovalent compounds dissolve in polar solvents like water because the forces of attraction between positive and negative charges become weak in water.

• But since covalent compound are made up of molecules, they do not ionize in water and hence do not dissolve in water.

48. What is the atomic number of sodium (Na) in the modern periodic table? [RRB RPF Constable Exam, 15.02.2019 Shift-I]

(1) 33
(2) 22
(3) 11
(4) 44

Correct Answer: (4) 44

Solution:Sodium is a chemical element with symbol 'Na' and atomic number 11. Since sodium can ignite on contact with water, it must be stored in a moisture free environment.

49. What is the other form of calcium carbonate? [RRB RPF Constable Exam, 18.02.2019 Shift-II]

(1) Limestone
(2) Chalk
(3) Marble
(4) All of the above

Correct Answer: (4) All of the above

Solution:Calcium carbonate is an Inorganic chemical compound with the chemical formula CaCO₃. It is also found in many forms such as chalk, marble, lime-stone, etc.

50. Which of the following methods is used for purification of nickel metal? [RRB RPF Constable Exam, 18.02.2019 Shift-II]

(1) Polling
(2) Separation
(3) Haber method
(4) Monde Method

Correct Answer: (4) Monde Method

Solution:Monde process is the method used for refining of nickel metal.

In this process, nickel is heated in a steam of carbon monoxide to form volatile nickel carbonyl Ni(CO)₄. Nickel carbonyl vapours on further heating decompose, giving pure nickel.