Chemistry (Part-III) (Railway)

31. What is the chemical formula of Phenol? [RRB RPF/RPSF SI Exam, 13.01.2019 Shift-III]

(1) C₆H₅OH
(2) C₂H₅OH
(3) C₄H₆OH
(4) C₄H₅OH

Correct Answer: (1) C₆H₅OH

Solution:Phenol is an aromatic organic compound with the molecular formula C₆H₅OH. It is a white crystalline solid that is volatile. The molecule consists of a phenyl group ("C₆H₅) bonded to a hydroxy group ("OH).

32. What is the substance which increases the reaction of a catalyst? [RRB RPF/RPSF SI Exam, 16.01.2019 Shift-II]

(1) Increaser
(2) Enhancer
(3) Venom
(4) Absorber

Correct Answer: (2) Enhancer

Solution:A catalyst is a substance that can be added to a reaction to increase the reaction-rate without getting consumed in the process. Catalysts typically speed up a reaction by reducing the activation energy or changing the reaction mechanism.

33. By what other name is tertiary coal known? [RRB RPF/RPSF SI Exam, 16.01.2019 Shift-II]

(1) Black coal
(2) Brown coal
(3) Gray Coal
(4) Yellow Coal

Correct Answer: (2) Brown coal

Solution:The Tertiary coal is also known as the 'brown coal'. Also known as brown coal. lignite is a lower grade coal and contains about 40 to 55 per cent carbon. Anthracite Coal is the best quality of coal and contains 80 to 95 per cent carbon.

34. If there is only water in the liquid medium, then the mixture is called ________ . [RRB RPF Constable Exam, 17.01.2019 Shit-III]

(1) Parasitic Mixture
(2) Heterogeneous Mixture
(3) Compound Mixture
(4) Collateral Mixture

Correct Answer: (4) Collateral Mixture

Solution:(4) Colloids (also known as colloidal solutions or colloidal systems) are mixtures in which microscopically dispersed insoluble particles of one substance are suspended in another substance.

• The colloidal dispersion of a liquid in a liquid is called emulsion. In these systems, one liquid is dispersed in another liquid immiscible with it.

35. Which of the following is a molecular element ? [RRB RPF Constable Exam, 17.01.2019 Shift-III]

(1) Chlorine
(2) Oxygen
(3) Sulphur
(4) Argon

Correct Answer: (4) Argon

Solution:Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in the Earth's atmosphere, at 0.934% (9340 ppmv).

36. Which one of the following is a fiber produced on wooden pulp by chemical reactions? [RRB RPF Constable Exam, 17.01.2019 Shift-III]

(1) Polyester
(2) Nylon
(3) Bag
(4) Rayon

Correct Answer: (4) Rayon

Solution:(4) Rayon is a man-made fiber prepared from a natural raw material called cellulose by chemical treatment.

• The cellulose required for making rayon is obtained from wooden pulp.

• Rayon is obtained by the chemical treatment of wood pulp.

37. The melting point of snow is _______ . [RRB RPF Constable Exam, 17.01.2019 Shift-III]

(1) 273.15 K
(2) 273.15° F
(3) 273.15° C
(4)273.15° R

Correct Answer: (1) 273.15 K

Solution:Melting point of snow is following

(i) at Kelvin scale 273.15k

(ii) at Fahrenheity 32°F

(iii) at Celesius scale -0°C

38. The atomic number is number of _________ in the nucleus of an atom. [RRB RPF Constable Exam, 17.01.2019 Shift-III]

(1) Photons
(2) Protons
(3) Neutrons
(4) Plasma

Correct Answer: (2) Protons

Solution:Atomic number is the number of protons, and therefore also the total positive charge, in the atomic nucleus. It is denoted by Z.

39. Which of the following is the most ductile metal ? [RRB RPF Constable Exam, 17.01.2019 Shift-III]

(1) Copper
(2) Silver
(3) Gold
(4) Platinum

Correct Answer: (3) Gold

Solution:Gold is the most ductile metal.

• The ability of metals to be drawn into thin wire is called ductility.

• A wire of about 2 Kms length can be drawn from one gram of gold.

40. Which of the following chemicals is responsible for aroma of fruit? [RRB RPF Constable Exam, 20.01.2019 Shift-III]

(1) Formaldehyde
(2) Thiocefone
(3) Esters
(4) Methanol

Correct Answer: (3) Esters

Solution:An ester is characterized by the orientation and bonding of the atoms shown, where R and R' are both carbon-initiated chains of varying length, also known as alkyl groups.

Esters are known for their distinctive odors and are commonly used for food aroma and fragrances.