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Practice MCQ Questions and answers on Chemistry-GK

Learn and practice General Knowledge questions and answers on Chemistry with very easy and understandable explanations. GK questions are very helpful different type of competitive exams. Page-6 section-1

Each section contains 100 MCQs on Chemistry .
51
The iron ore magnetite consists of
Discuss
Answer & Solution
Answer: Option A
Solution:
The iron ore magnetite consists of Fe2O3.
52
The ionisation energy of hydrogen atom in the ground state is x KJ. The energy required for an electron to jump from 2nd orbit to 3rd orbit is
Discuss
Answer & Solution
Answer: Option A
Solution:
The ionisation energy for the hydrogen atom can be written as:
Ionisation energy = energy in first orbit - energy in infinite orbit
Ionisation energy = ​ E = -E0 / n2 , where E0  = 13.6 eV (1 eV = 1.602×10-19  Joules) and n = 1,2,3… and so on.
The difference in energy = Einfinity - E1
so the ionisation energy from the ground state = x KJ = 0-( -E0 /12 ) = E0
The energy required to jump the elctron from second to the third stage is: Chemistry mcq solution image
53
The major constituent of air is
Discuss
Answer & Solution
Answer: Option B
Solution:
Below a height of about 86 kilometers, the three main gaseous elements, which together account for about 99.9% of the total atmosphere, exist in essentially constant proportion to the total: nitrogen comprises 78% of air by volume, oxygen comprises 21% of air by volume, and argon comprises another 0.9%.
54
The main chemical constituent of clay is
Discuss
Answer & Solution
Answer: Option D
Solution:
Aluminium silicate is the main Chemical constituent of clay.
55
The mineral containing both magnesium and calcium is
Discuss
Answer & Solution
Answer: Option D
Solution:
The mineral containing both magnesium and calcium is Dolomite.
56
The metal does not give H2 on treatment with dilute HCL is
Discuss
Answer & Solution
Answer: Option C
Solution:
The metal does not give H2 on treatment with dilute HCL is Ag.
57
The number of g-molecule of oxygen in 6.02 x 1024 CO molecules is
Discuss
Answer & Solution
Answer: Option C
Solution:
In this question gram molecules simply means number of moles of O2 molecules.
So we have 6.02*10^24 atoms of Oxygen means 3.01*10^24 molecules of O2.
3.01*10^24 molecules of O2 are equal to 5 moles.

Source : Quora.com

58
The most extensive, commercially useful source of thorium as monazite sand occurs in India at
Discuss
Answer & Solution
Answer: Option B
Solution:
The most extensive, commercially useful source of thorium as monazite sand occurs in India at Travancore coast.
59
The main active constituent of tea and coffee is
Discuss
Answer & Solution
Answer: Option C
Solution:
Caffeine is the main active constituent of tea and coffee.
60
The maximum number of isomers for an alkene with molecular formula C4H8 is
Discuss
Answer & Solution
Answer: Option B
Solution:
The maximum number of isomers for an alkene with molecular formula C4H8 is 4.