Chemistry (Part-II) (Railway)

Total Questions: 50

41. All the member of a homologous series can be represented by the same general formula. Choose the INCORRECT formula from among the following. [RRB ALP & Technician Exam, 30.08.2018 Shift-III]

(1) Alkene — CₙH₂ₙ₊₃
(2) Alkane — CₙH₂ₙ₋₂ and Alkyne — CₙH₂ₙ₋₂
(3) Alkyne — CₙH₂ₙ₋₂
(4) Alkane— CₙH₂ₙ₊₂

Correct Answer: (1) Alkene — CₙH₂ₙ₊₃

Solution:Alkanes, alkenes and alkynes are simple hydrocarbon chains with no functional groups. Alkanes are identified because the carbon chain has only single bonds. Common alkanes include methane (natural gas), propane (heating and cooking fuel), butane (lighter fluid) and octane (automobile fuel). Alkenes have at least one double bond and alkynes have at least one triple bond. The most common alkyne is ethyne, better known as acetylene. The general formula for alkanes is CₙH₂n+₂, where n is the number identified by the prefix. Alkenes have the formula CₙH₂n and alkynes use the formula CnH₂n-₂.

42. Select the INCORRECT set of Molecular Formula - IUPAC Name - Common Name from the following options. [RRB ALP & Technician Exam, 31.08.2018 Shift-I]

(1) C₄H₉OH–Butanol–Butyl Alcohol
(2) C₂H₅OH–Ethanol–Ethyl Alcohol
(3) C₃H₇OH–Propanol–Propyl Alcohol
(4) C₂H₃OH–Methanol–Methyl Alcohol

Correct Answer: (4) C₂H₃OH–Methanol–Methyl Alcohol

Solution:The chemical formula of Methanol, also known as methyl alcohol, CH₃OH. It is the simplest alcohol, consisting of a methyl group linked to a hydroxyl group. It is a light, volatile, colorless, flammable liquid with a distinctive odor similar to that of ethanol (drinking alcohol).

43. Acids that contain Hydrogen and other non-metallic element(s), except Oxygen, are called: [RRB ALP & Technician Exam, 31.08.2018 Shift-I]

(1) Strong acid
(2) Weak acid
(3) Hydracid
(4) Dilute acid

Correct Answer: (3) Hydracid

Solution:(3) Hydracid is an acid, such as hydrochloric acid, that does not contain any oxygen as opposed to an oxyacid; they are all binary compounds of hydrogen and a halogen or pseudo halogen.

44. Which of the following is NOT a constituent of biogas? [RRB ALP & Technician Exam, 31.08.2018 Shift-I]

(1) Hydrogen Sulphide
(2) Methane
(3) Carbon Monoxide
(4) Carbon Dioxide

Correct Answer: (3) Carbon Monoxide

Solution:The major constituents of biogas are methane (CH₄, 60 percent or more by volume) and carbon dioxide (CO₂, about 35 percent); but small amounts of water vapour, hydrogen sulfide (H₂S), carbon monoxide (CO), and nitrogen (N₂) are also present. Best Option: (3) Carbon Monoxide

45. Which of the following elements was the last element in Newland's Law of Octaves? [RRB ALP & Technician Exam, 31.08.2018 Shift-I]

(1) Bromine
(2) Hydrogen
(3) Thorium
(4) Rubidium

Correct Answer: (3) Thorium

Solution:Only 56 elements were known till the time of Newlands. The last element known was thorium with atomic mass 232. Newlands' law of octave was applicable only up to calcium with atomic mass 40.1. Now there are ninety elements known up to thorium.

46. ________ is the most ductile metal. [RRB ALP & Technician Exam, 31.08.2018 Shift-I]

(1) Pt
(2) Au
(3) Ag
(4) C

Correct Answer: (1) Pt

Solution:The most ductile metal is platinum (Pt) and the most malleable metal is gold (Ag).

47. Which of the following statements is wrong with regard to strong acids? [RRB ALP & Technician Exam, 31.08.2018 Shift-I]

(1) Strong acids react very rapidly with other substances (such as metal carbonates and metal hydrogen carbonates).
(2) Hydrochloric Acid, Sulphuric acid and Nitric Acid are strong acids.
(3) Acids are those chemical substances that have a salty taste
(4) All mineral acids are strong acids.

Correct Answer: (3) Acids are those chemical substances that have a salty taste

Solution:Acids have sour taste when in aqueous solution. This is because of their hydrogen ion concentration. Common acids include hydrochloric acid. acetic acid, sulphuric acid and citric acid (found in citrus fruits).

48. Saturated Hydrocarbons are called: [RRB ALP & Technician Exam, 31.08.2018 Shift-III]

(1) alkynes
(2) isomers
(3) alkanes
(4) alkenes

Correct Answer: (3) alkanes

Solution:In organic chemistry, an alkane, or paraffin is an acyclic saturated hydrocarbon. In otherwords, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon-carbon bonds are single. Alkanes have the general chemical formula CnHn2n+2.

49. Which of the following metals is found in free state? [RRB ALP & Technician Exam, 31.08.2018 Shift-III]

(1) Sodium
(2) Gold
(3) Potassium
(4) Calcium

Correct Answer: (2) Gold

Solution:A noble metal is a metal or alloy characterized by its lack of chemical reactivity. These metals resist oxidation and corrosion in any environment. They are the opposite of base metals, which more readily oxidize and corrode. Gold is the least reactive metal, hence always found in free state.

50. Alkali metals are assigned which group in the Modern Periodic Table?

(1) Second group
(2) Eighteenth group
(3) Third group
(4) First group

Correct Answer: (4) First group

Solution:Alkali metals are the chemical elements found in Group I of the periodic table. The alkali metals include: lithium, sodium, potassium, rubidium, cesium, and francium. Although often listed in Group I due to its electronic configuration, hydrogen is not technically an alkali metal since it rarely exhibits similar behavior. Alkali metals are among the most reactive metals.

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