Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
21. Which of the following is an example of a Thermosetting plastic?
[A] Melamine
[B] Bakelite
[C] Formaldehyde resin
[D] Teflon
Show Answer
Correct Answer: D [Teflon]
Notes:
A Thermosetting polymer can be heated only once when it permanently sets into a solid which can not be remelted and remoulded. The thermosetting plastic is cross linked and is permanently rigid. The common example are bakelite, melamine, formaldehyde resin, etc. Teflon is a thermoplastic.
22. What do we call the polymer which is formed from more than one kind of monomer?
[A] Homopolymer
[B] Copolymer
[C] Megapolymer
[D] Heteropolymer
Show Answer
Correct Answer: B [Copolymer]
Notes:
A polymer formed from more than one kind of monomer units is called copolymer or mixed polymer. A polymer formed from only one kind of monomers is called homopolymer.
23. Which of the following non-metal is used for bleaching woodpulp?
[A] Argon
[B] Chlorine
[C] Fluorine
[D] Gallium
Show Answer
Correct Answer: B [ Chlorine ]
Notes:
Chlorine is used for bleaching woodpulp, which is required for the manufacture of paper and rayon). It is a greenish yellow gas with pungent and suffocating odour.
24. Which of these cannot be the reason for the permanent hardness in water?
[A] calcium sulphate
[B] calcium chloride
[C] calcium bicarbonate
[D] None of the above
Show Answer
Correct Answer: C [calcium bicarbonate]
Notes:
The permanent hardness in water is due to the presence of calcium sulphate/calcium chloride and/or magnesium sulphate/magnesium chloride in water.
25. What salts are soaps commonly made up of?
[A] Sodium or Potassium salts of long chain fatty acids
[B] Magnesium or Aluminium salts of long chain fatty acids
[C] Cobalt or Copper salts of long chain fatty acids
[D] All of the above
Show Answer
Correct Answer: A [Sodium or Potassium salts of long chain fatty acids]
Notes:
Soaps used for cleaning purpose are sodium or potassium salts of long chain fatty acids, e.g., stearic, oleic and palmitic acids.
26. Which of these drugs is called as the ‘love drug’?
[A] Mescalin
[B] MDMA
[C] Dextromethorphan
[D] Ketamine
Show Answer
Correct Answer: B [ MDMA]
Notes:
MDMA or 3,4-methylenedioxy-methamphetamine is a synthetic drug that alters mood and perception (awareness of surrounding objects and conditions). It is called as the love drug when used recreationally.
27. 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.
28. What is dry ice?
[A] Liquid nitrogen
[B] Water ice
[C] Solid carbon dioxide
[D] Frozen ethanol
Show Answer
Correct Answer: C [Solid carbon dioxide]
Notes:
“Dry ice” is solid carbon dioxide (CO2). Carbon dioxide freezes at -78.5 degrees Centigrade. When dry ice “melts” it undergoes a process called sublimation. This means that it is converted from a solid directly to a gas, bypassing the intermediate liquid stage. This is where the name “dry ice” comes from – when it melts, you never get any liquid, hence it’s “dry”.
29. Who among the following invented Dynamite?
[A] JB Dunlop
[B] Alfred Nobel
[C] James Simons
[D] Peter Hargreaves
Show Answer
Correct Answer: B [Alfred Nobel]
Notes:
Alfred Bernhard Nobel was a Swedish businessman, chemist, engineer, inventor, and philanthropist. Nobel held 355 different patents, dynamite being the most famous. The synthetic element nobelium was named after him.
30. Which of the following is a characteristic of an exothermic reaction?
[A] Release of heat
[B] Absorption of heat
[C] Doesn’t involve any change in temperature
[D] None of the above
Show Answer
Correct Answer: A [Release of heat]
Notes:
An exothermic reaction is a chemical reaction that releases energy through light or heat. It is the opposite of an endothermic reaction. Expressed in a chemical equation: reactants – products + energy.
