Chemistry (Part-II) (Railway)

Total Questions: 50

11. By how many atomic mass units do subsequent members of homologous series differ? [RRB ALP & Technician Exam,21.08.2018 Shift-I]

(1) 26
(2) 32
(3) 20
(4) 14

Correct Answer: (4) 14

Solution:Homologous series is a series of compounds with similar chemical properties and same functional group differing with the successive member by CH₂. By calculating the molecular mass of CH₂, we will get it as 14u. As molar mass of carbon is 12 and hydrogen is 1. Hence the two members of homologous members differs by (12 + 1 × 2 ) u = 14u.

12. Which of the following metals displaces Iron from Iron Chloride? [RRB ALP & Technician Exam, 21.08.2018 Shift-I]

(1) Lead
(2) Tin
(3) Silver
(4) Zinc

Correct Answer: (4) Zinc

Solution:A metal will displace (take the place of) a less reactive metal in a metal salt solution. In the Reactivity Series of metals, Lead, tin and silver are less reactive than iron, while Zinc is more reactive than Iron. So, it displaces iron from Iron chloride.

13. Identify a use of the isotope of uranium. [RRB ALP & Technician Exam, 21.08.2018 Shift-I]

(1) Treatment of cancer
(2) Fuel in aeroplanes
(3) Treatment of goitre
(4) Fuel in nuclear reactors

Correct Answer: (4) Fuel in nuclear reactors

Solution:Naturally occurring uranium is composed of three major isotopes, uranium-238, uranium-235, and uranium-234. All three isotopes are radioactive. The isotope uranium-235 is important for both nuclear reactors and nuclear weapons because it is the only isotope existing in nature to any appreciable extent that is fissile, that is, can be broken apart by thermal neutrons. The isotope uranium-238 is also important because it absorbs neutrons to produce a radioactive isotope that subsequently decays to the isotope plutonium-239, which is also fissile

14. Which of the following is NOT a property of bases? [RRB ALP & Technician Exam, 21.08.2018 Shift-III]

(1) They react with acids and neutralise them
(2) They turn red litmus blue
(3) They turn blue litmus red
(4) They have bitter taste

Correct Answer: (3) They turn blue litmus red

Solution:Bases taste bitter, feel slippery, and conduct electricity when dissolved in water. Indicator compounds such as litmus can be used to detect bases. Bases turn red litmus paper blue.

15. Which type of reaction occurs when carbon burns in oxygen to give carbon dioxide? [RRB ALP & Technician Exam, 21.08.2018 Shift-III]

(1) Addition reaction
(2) Substitution reaction
(3) Combustion reaction
(4) Decomposition reaction

Correct Answer: (3) Combustion reaction

Solution:A combustion reaction is any reaction in which a combustible material combines with oxygen or is oxidized. The most common combustion reaction is a fire, in which hydrocarbons burn in air to produce carbon dioxide, water vapor, heat, light and often ashes.

16. Which of the following is used as a catalyst in the hydrogenation of vegetable oil? [RRB ALP & Technician Exam, 21.08.2018 Shift-III]

(1) He
(2) H₂
(3) Ni
(4) Pb

Correct Answer: (3) Ni

Solution:Dring hydrogenation, vegetable oils are reacted with hydrogen gas at about 60°C. A nickel catalyst is used to speed up the reaction. The double bonds are converted to single bonds in the reaction. In this way unsaturated fats can be made into saturated fats.

17. Fill in the blank with the most appropriate option. An element attains stability when it achieves _________ state. [RRB ALP & Technician Exam, 21.08.2018 Shift-III]

(1) an only-duplet
(2) an only-octet
(3) a duplet or octet
(4) a heptate

Correct Answer: (3) a duplet or octet

Solution:The word octet refers to the number eight, and the word duplet is related to "doublet" and refers to a pair or to the number two. An element achieves stability when it achieves these two states.

18. Burning Magnesium ribbon produces white ash, which dissolves in water to form _________ . [RRB ALP & Technician Exam, 21.08.2018 Shift-III]

(1) Magnesium Halides
(2) Magnesium Oxide
(3) Magnesium Hydroxide
(4) Magnesium Sulphate

Correct Answer: (3) Magnesium Hydroxide

Solution:White ash obtained from magnesium ribbon is magnesium oxide, when dissolved in water forms Magnesium hydroxide or Milk of Magnesia.

19. The primitive atmosphere was reducing because: [RRB ALP & Technician Exam, 21.08.2018 Shift-III]

(1) Hydrogen atoms were few
(2) Hydrogen atoms were active and in greater numbers
(3) Oxygen atoms were more
(4) Nitrogen atoms were more

Correct Answer: (2) Hydrogen atoms were active and in greater numbers

Solution:A reducing atmosphere. also known as a reduction atmosphere, is an atmosphere without significant amounts of free oxygen (O₂) and other oxidising gases or vapours thus preventing oxidation. Chemists refer to an atmosphere with abundance of hydrogen atoms, or other substances that readily provide electrons, and a scarcity of oxygen and nitrogen atoms.

20. Which of the following is a chemical change? [RRB ALP & Technician Exam, 29.08.2018 Shift-I]

(1) Butter turning rancid
(2) Making dry ice from CO₂
(3) Heating a platinum wire
(4) Magnetisation of iron

Correct Answer: (1) Butter turning rancid

Solution:The turning of butter into rancid is a purely chemical change. This is because bacteria in the butter turns the lactose and sugars found in butter into lactic acid. Rancidity is a process in which the food containing oil and fat get oxidised, leading to unpleasant smell with an unpleasant taste.

« Previous 123 4 5 Next »