General Science Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination
41. What do we call the ratio of number of fission produced by a given generation of neutrons to the number of fission of the preceding generation?
[A] Critical factor
[B] Energy factor
[C] Multiplication factor
[D] Moderation factor
Show Answer
Correct Answer: C [Multiplication factor]
Notes:
The multiplication factor is the ratio of number of fission produced by a given generation of neutrons to the number of fission of the preceding generation.
42. Which of the following material is used to make control rods in a nuclear reactor?
[A] Indium
[B] Boron
[C] Cadmium
[D] All of the above
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Correct Answer: D [All of the above]
Notes:
The reaction rate is controlled through control-rods made out of neutron-absorbing materials. They are composed of chemical elements such as boron, silver, indium and cadmium that are capable of absorbing many neutrons without themselves fissioning.
43. Which of the following is emitted in alpha decay?
[A] Helium nucleus
[B] Hydrogen nucleus
[C] Electrons
[D] Carbon nucleus
Show Answer
Correct Answer: A [Helium nucleus]
Notes:
In alpha decay, Helium nucleus is emitted. Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus transforms or ‘decays’ into a different atomic nucleus, with a mass number that is reduced by four and an atomic number that is reduced by two.
44. Which of the following reactions take place when iron nail in a copper sulphate solution becomes brownish in colour?
[A] Decomposition reaction
[B] Displacement reaction
[C] Double Displacement reaction
[D] None of the above
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Correct Answer: B [Displacement reaction]
Notes:
Iron nail in the Copper Sulphate solution become brownish in colour and the blue colour of copper sulphate solution fade. This happens because iron has displaced or removed another element, copper, from copper sulphate solution. This reaction is known as displacement reaction.
45. Which of these methods can be used to prevent rancidity?
[A] Adding antioxidants to the food
[B] Storing food at low temperature
[C] Replace the air with nitrogen in the packing material
[D] All of the above
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Correct Answer: D [All of the above]
Notes:
When food containing fats and oils are exposed to the atmosphere, the oxidation of fat and oil occurs, this is called as Rancidity.
46. What is the sum of powers of the concentration of the reactants called as?
[A] Order of reaction
[B] Stage of reaction
[C] Zone of reaction
[D] None of the above
Show Answer
Correct Answer: A [Order of reaction]
Notes:
The sum of powers of the concentration of the reactants in the rate law expression is known as the order of that chemical reaction.
47. What is the relationship between half-life period and initial concentration of the reacting species for a first order reaction?
[A] Both are directly proportional to each other
[B] Both are inversely proportional to each other
[C] Both are independent of each other
[D] The half life is twice the concentration of reacting species
Show Answer
Correct Answer: C [Both are independent of each other]
Notes:
For a first order reaction, half-life period is constant, i.e., it is independent of initial concentration of the reacting species. for a zero order reaction, it is directly proportional to the initial concentration of the reactants and inversely proportional to the rate constant. .
48. Who gave the law of octaves for arrangement of elements?
[A] Lothar Meyer
[B] Dmitri Mendeleev
[C] John Alexander Newlands
[D] Johann Dobereiner
Show Answer
Correct Answer: C [John Alexander Newlands]
Notes:
Newland law of octaves states that If the elements are arranged in order of their increasing atomic weights, every 8th element had similar properties to the first one. It was similar as the first and eighth note in music.
49. From which element in the modern periodic table, the 3d transition series starts?
[A] Zinc
[B] Iron
[C] Scandium
[D] Copper
Show Answer
Correct Answer: C [Scandium]
Notes:
The 3d transition series starts from scandium (Z = 21) and completes at zinc (Z=30). Reason for this transition series is that before the 4p orbital is filled, filling up of 3d orbitals becomes energetically favourable.
50. The Lanthanoids are part of which of the following block of elements in the periodic table?
[A] p-block
[B] s-block
[C] d-block
[D] f-block
Show Answer
Correct Answer: D [f-block]
Notes:
Lanthanoids form part of the series of chemical elements comprising the 15 metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium. They are a part of f-block of elements in the periodic table
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