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
51. What is the difference between the mass number of Parent nucleus and Daughter nucleus in an alpha-decay process?
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Correct Answer: B [4]
Notes:
In α-decay, the mass number of the product nucleus (daughter nucleus) is four less than that of the decaying nucleus (parent nucleus), while the atomic number decreases by two.
52. Which of these processes is responsible for the energy released in an atom bomb?
[A] Nuclear Fission
[B] Nuclear Fusion
[C] Gamma decay
[D] None
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Correct Answer: A [Nuclear Fission]
Notes:
The source of energy in nuclear reactors, which produce electricity, is nuclear fission. The enormous energy released in an atom bomb comes from uncontrolled nuclear fission.
53. Which of the following gas is used to prevent the chips from getting oxidised?
[A] Oxygen
[B] Nitrogen
[C] Helium
[D] Lithium
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Correct Answer: B [Nitrogen]
Notes:
The chips manufacturers usually flush bags of chips with gas such as nitrogen to prevent the chips from getting oxidised.
54. Which of the following equation represents combination of Hydrogen gas with nitrogen to form ammonia?
[A] 2H2 + N –> NH3
[B] 2H + N3 –> NH3
[C] 3H2 + N2 –> 2NH3
[D] None of the above
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Correct Answer: C [3H2 + N2 –> 2NH3]
Notes:
3H2 + N2 –> 2NH3 is the balance equation which represents combination of Hydrogen gas with nitrogen to form ammonia.
55. Which of the following is correct about the properties of the elements as per the Mendeleev’s Periodic Law?
[A] they are a periodic function of the element’s atomic number
[B] they are a periodic function of the element’s atomic weight
[C] they don’t depend on the element’s atomic weight
[D] they are same for every 4th element
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Correct Answer: B [they are a periodic function of the element’s atomic weight]
Notes:
As per Mendeleev’s Periodic Law, the properties of the elements are a periodic function of their atomic weights.
56. Which of the following was equal to the atomic weight of the middle element in the Dobereiner’s Triads?
[A] arithmetic mean of the atomic weights of the other two elements
[B] geometric mean of the atomic weights of the other two elements
[C] difference between the atomic weights of the other two elements
[D] sum of the atomic weights of the other two elements
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Correct Answer: A [arithmetic mean of the atomic weights of the other two elements]
Notes:
Dobereiner was the first scientist to classify the elements in some groups. In the triads of elements the atomic weight of the middle element was the arithmetic mean of the atomic weights of the other two.
57. Who gave the law of octaves for arrangement of elements?
[A] Lothar Meyer
[B] Dmitri Mendeleev
[C] John Alexander Newlands
[D] Johann Dobereiner
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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.
58. Which of the following is correct about Mendeleev’s Periodic Table?
[A] Argon is placed before Potassium
[B] Cobalt is placed before Nickel
[C] Tellurium is placed before iodine
[D] All of the above
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Correct Answer: D [All of the above]
Notes:
All statements represent the anomalous pairs of elements in Mendeleev’s Periodic Table. The atomic mass of argon is 39.9 and that of potassium 39.1. But argon is placed before potassium in the periodic table. Similarly, Tellurium is placed before iodine and Cobalt is placed before Nickel.
59. Which of the following elements have ns1 outermost electronic configuration?
[A] s-block elements
[B] p-block elements
[C] d-block elements
[D] f-block elements
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Correct Answer: A [s-block elements]
Notes:
The elements of Group 1 (alkali metals) and Group 2 (alkaline earth metals) which have ns1 and ns1 outermost electronic configuration belong to the s-Block Elements.
60. Which of the following elements is identified by the 7th group and 4th period of the modern periodic table?
[A] Copper
[B] Iron
[C] Manganese
[D] Chromium
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Correct Answer: C [Manganese]
Notes:
Manganese is placed in the 7th group and 4th period of the modern periodic table. Its Atomic number is 25 and is placed group VII A.
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