Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
11. Which of the following is NOT correct about Group 14 elements?
[A] All of them are solids
[B] Melting points are much higher than those of corresponding elements of group 13
[C] Carbon is a non-metal
[D] Germanium is a metal
Show Answer
Correct Answer: D [Germanium is a metal]
Notes:
All members of group 14 are solids. Carbon and silicon are non-metals, germanium is a metalloid, whereas tin and lead are soft metals. Melting points and boiling points of group 14 elements are much higher than those of corresponding elements of group 13.
12. Water Gas is a mixture of?
[A] CO and H2
[B] CO and H2O
[C] CO2 and H2
[D] None of the Above
Show Answer
Correct Answer: A [CO and H2]
Notes:
The mixture of CO and H2 produced is known as water gas or synthesis gas.
13. What is dry ice?
[A] solidified form of Carbon dioxide
[B] frozen heavy water
[C] isotope of Hydrogen
[D] popular name of Benzene
Show Answer
Correct Answer: A [solidified form of Carbon dioxide]
Notes:
Carbon dioxide can be obtained as a solid in the form of dry ice by allowing the liquified CO2 to expand rapidly.
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. Which of the following is an example of colloidal solution?
[A] Milk
[B] Fog
[C] Smoke
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Milk, Fog, Smoke, Cheese, Clouds, Mist, Shaving cream, Butter, Jelly etc. are some of the examples of colloidal solution.
16. Which of the following is / are correct statement(s) about Gypsum?
[A] It’s a mineral composed of calcium sulfate dihydrate
[B] It is a soft mineral
[C] It is commonly added to saline soils to reduce salinity
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Gypsum is a mineral composed of calcium sulfate dihydrate. It’s a soft mineral and colorless to white in color. It is commonly added to saline soils to reduce salinity and also used in wallboard (drywall) and plaster of paris.
17. Galena is an ore of which of the following metals?
[A] Tin
[B] Copper
[C] Lead
[D] Gold
Show Answer
Correct Answer: C [Lead]
Notes:
Galena is an ore of Lead. It is also known as lead glance. It is the natural mineral form of lead sulfide (PbS).
18. Which of the following quantum number is also known as orbital angular momentum?
[A] Principal quantum number
[B] Azimuthal quantum number
[C] Magnetic quantum number
[D] Electron spin quantum number
Show Answer
Correct Answer: B [Azimuthal quantum number]
Notes:
Azimuthal quantum number is also known as orbital angular momentum or subsidiary quantum number. It is represented by ‘l’.
19. What is the bond angle in case of Ammonia molecule?
[A] 120°
[B] 150°
[C] 66°
[D] 107°
Show Answer
Correct Answer: D [107°]
Notes:
The bond angle in case of Ammonia molecule is 107° and the molecular geometry is trigonal pyramidal. The number of bond pairs in Ammonia is 3 and lone pair is 1.
20. Which of the following represents the bond order in Molecular orbital theory?
[A] half the difference between the number of bonding and antibonding electrons
[B] twice the difference between the number of bonding and antibonding electrons
[C] the difference between the number of bonding and antibonding electrons
[D] the sum of the number of bonding and antibonding electrons
Show Answer
Correct Answer: A [half the difference between the number of bonding and antibonding electrons]
Notes:
The bond order in Molecular orbital theory is given by half the difference between the number of bonding and antibonding electrons.
