Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
11. Choose the correct about Methyl Orange as an indicator?
[A] It turns red in acidic medium and green in basic medium
[B] It turns colourless in acidic medium and yellow in basic medium
[C] It turns red in acidic medium and yellow in basic medium
[D] It turns colourless in acidic medium and red in basic medium
Show Answer
Correct Answer: C [It turns red in acidic medium and yellow in basic medium]
Notes:
Methyl orange is a pH indicator for testing acids and bases. Methyl orange shows red color in acidic medium and yellow color in basic medium.
12. What do we call the device which uses electrical energy to carry non-spontaneous chemical reactions?
[A] Voltaic cell
[B] Galvanic cell
[C] Daniel cell
[D] Electrolytic cell
Show Answer
Correct Answer: D [Electrolytic cell]
Notes:
An electrolytic cell is an electrochemical cell which uses electrical energy to drive a non-spontaneous redox reaction.
13. Where does the oxidation takes place in a Galvanic cell?
[A] Anode
[B] Cathode
[C] Oxidation does not take place
[D] None of the above
Show Answer
Correct Answer: A [Anode]
Notes:
In a galvanic cell, the half-cell in which oxidation takes place is called anode and it has a negative potential with respect to the solution. The other half-cell in which reduction takes place is called cathode and it has a positive potential with respect to the solution.
14. Which of these non-metals finds its use as a diluent for oxygen in modern diving apparatus?
[A] Neon
[B] Helium
[C] Bromine
[D] Argon
Show Answer
Correct Answer: B [ Helium ]
Notes:
Helium is used as a diluent for oxygen in modern diving apparatus because of its very low solubility in blood. Helium is a non-inflammable and light gas.
15. Which of the following gas is also known as laughing gas?
[A] Nitrous oxide
[B] Nitrogen dioxide
[C] Nitrogen hydroxide
[D] Nitrogen peroxide
Show Answer
Correct Answer: A [ Nitrous oxide]
Notes:
Nitrous oxide, commonly known as laughing gas is a colourless non-flammable gas, with a slight metallic scent and taste. It is also used in surgery and dentistry, for its anesthetic and pain reducing effects.
16. Which among the following metals is the hardest metal?
[A] Platinum
[B] Gold
[C] Iron
[D] Tungsten
Show Answer
Correct Answer: D [Tungsten]
Notes:
Tungsten has the highest tensile strength of any natural metal, with an ultimate strength of 1510 megapascals. Tungsten has the highest melting point (3422 °C, 6192 °F), lowest vapor pressure (at temperatures above 1650 °C, 3000 °F).
17. What happens when the temperature of water falls from 30°C and 0°C?
[A] The volume of ice formed will be less than volume of water
[B] The volume of ice formed will be more than the volume of water
[C] Water will not freeze at 0°C
[D] None of the above
Show Answer
Correct Answer: B [The volume of ice formed will be more than the volume of water]
Notes:
The formation of ice will took place as temperature falls from 30 degree Celsius to 0 degree Celsius. The volume of ice thus formed will be more than the volume of water.
18. Which of the following is the process by which metal surface is coated with thin layer of zinc? (UPSC Prelims 1982)
[A] Vulcanising
[B] Galvanising
[C] Electroplating
[D] None of these
Show Answer
Correct Answer: B [Galvanising]
Notes:
Galvanization is a process in which coat of zinc is applied to the thicker base metal surface which are prone to corrosion such as iron. The most common method is hot-dip galvanizing, in which the parts are submerged in a bath of molten zinc.
19. Which among the following is the common ore of aluminium? (UPSC Prelims 1983)
[A] Bauxite
[B] Chromite
[C] Cryolite
[D] Monazite
Show Answer
Correct Answer: A [Bauxite]
Notes:
Bauxite ore is the main source of aluminum. It contains the aluminum minerals gibbsite, boehmite, and diaspore.
20. Which of the following is not an alloy? (UPSC Prelims 1984)
[A] Bronze
[B] Brass
[C] Steel
[D] Zinc
Show Answer
Correct Answer: D [Zinc]
Notes:
• Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (such as aluminium, manganese, nickel or zinc) and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon.
• Brass is an alloy of copper and zinc, in proportions which can be varied to achieve varying mechanical and electrical properties.
• Steel, alloy of iron and carbon in which the carbon content ranges up to 2 percent (with a higher carbon content, the material is defined as cast iron).
• Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a blue-silvery appearance.
