Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination. These questions are part of GKToday’s 35000+ MCQs Bank Course in GKToday Android App
11. What is the maximum stress after which the wire breaks called as?
[A] Tensile strength
[B] Shear strength
[C] Bulk strength
[D] Hooke’s strength
Show Answer
Correct Answer: A [Tensile strength]
Notes:
The maximum stress after which the wire begin to flow and breaks, is called breaking stress or tensile strength. The force by application of which the wire breaks is called the breaking force.
12. How many groups of p–block elements are there in the periodic table?
[A] 4
[B] 6
[C] 8
[D] 3
Show Answer
Correct Answer: B [6]
Notes:
There are six groups of p–block elements in the periodic table numbering from 13 to 18.
13. Which of these is NOT a compound of carbon?
[A] Acetic acid
[B] Chloroform
[C] Caustic Soda
[D] Methane
Show Answer
Correct Answer: C [Caustic Soda]
Notes:
Caustic soda is a compound of sodium where as Acetic acid, Chloroform and Methane are the compounds of carbon.
14. Which of the following metal is alloyed with pure gold to make gold ornaments?
[A] Silver
[B] Copper
[C] Zinc
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
24 carat gold is considered to be the purest form of gold but it is too soft to be made into jewellery. It is alloyed with metals like zinc, cadmium, silver or copper to make it hard.
15. What is the S.I unit of activity?
[A] becquerel
[B] curie
[C] candela
[D] henry
Show Answer
Correct Answer: A [becquerel]
Notes:
The SI unit for activity is becquerel, named after the discoverer of radioactivity, Henry Becquerel. The c.g.s unit of activity is curie.
16. 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
Show Answer
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.
17. What is the reason for the increase in the electronegativity across a period from left to right?
[A] attraction between the valence electrons and the nucleus increases
[B] attraction between the valence electrons and the nucleus decreases
[C] increase in the atomic weight
[D] None of the above
Show Answer
Correct Answer: A [attraction between the valence electrons and the nucleus increases]
Notes:
The attraction between the outer (or valence) electrons and the nucleus increases as the atomic radius decreases in a period. The electronegativity also increases.
18. Choose the correct statement:
[A] A cation and an anion are smaller than their parent atom
[B] An Anion with the greater negative charge has larger radius
[C] Both a and b
[D] None of the above
Show Answer
Correct Answer: B [An Anion with the greater negative charge has larger radius]
Notes:
A cation is smaller than its parent atom because it has fewer electrons while its nuclear charge remains the same. The size of an anion will be larger than that of the parent atom because the addition of one or more electrons would result in increased repulsion among the electrons and a decrease in effective nuclear charge. Also, An Anion with the greater negative charge has larger radius.
19. What amount of carbon dioxide is present in earth’s atmosphere?
[A] 12%
[B] 1%
[C] 0.04%
[D] 3.8%
Show Answer
Correct Answer: C [0.04%]
Notes:
Earth’s atmosphere contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases.
20. What is the common name of But-2-yne?
[A] Acetylene
[B] Methylacetylene
[C] Ethylacetylene
[D] Dimethylacetylene
Show Answer
Correct Answer: D [Dimethylacetylene]
Notes:
Dimethylacetylene is the common name of But-2-yne. Ethylacetylene is the common name of But-1-yne. Methylacetylene is the common name of Propyne. Acetylene is the common name of Ethyne.
