Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. Which among the following compound is most commonly used in the Photochromic lenses?
[A] Potassium Dichromate
[B] Silver Chloride
[C] Potassium ferrate
[D] Ferric Chloride
Show Answer
Correct Answer: B [Silver Chloride]
Notes:
Photochromatic or Photochromic glass acquires a darker shade when exposed to bright light and returns to its original lighter shade in dim light. This happens because silver halides (iodide or chloride) is added to this glass
2. Which among the following happens in an oxidation reaction ?
[A] Electrons are gained
[B] Electrons are lost
[C] Protons are gained
[D] Protons are lost
Show Answer
Correct Answer: B [Electrons are lost ]
Notes:
Oxidation is the loss of electrons during a reaction by a molecule, atom or ion. When oxidation occurs, an element loses electrons and its oxidation number increases .i.e. it becomes more positive.
3. Which of the following is the correct term used to describe Graphite, Carbon and Diamonds?
[A] Isotopes
[B] Isomers
[C] Isotones
[D] Allotropes
Show Answer
Correct Answer: D [Allotropes]
Notes:
Allotropes refer to two or more different physical forms in which an element can exist. The property is due to different ways atoms bond together. The most common instance is the element carbon, which exists in several different forms, including diamond, graphite, and fullerenes, making it an allotropic element. It’s crucial to note that allotropy applies to elements, not compounds.
4. Amalgam’ is a term used for an alloy of a metal with :
[A] Copper
[B] Mercury
[C] Lead
[D] Aluminium
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Correct Answer: B [Mercury]
Notes:
The correct answer is Mercury. An amalgam is a specific type of alloy that primarily consists of mercury mixed with another metal, commonly used in dental fillings due to its durability and ease of use. Historically, amalgams have been used since ancient times, with the earliest known use dating back to the 9th century in China.
5. Which of the following is NOT correct about the use of Quick lime?
[A] Manufacturing of cement
[B] Manufacture of sodium carbonate
[C] Purification of sugar
[D] used to extinguish fire
Show Answer
Correct Answer: D [used to extinguish fire]
Notes:
(i) It is an important primary material for manufacturing cement and is the cheapest form of alkali. (ii) It is used in the manufacture of sodium carbonate from caustic soda. (iii) It is employed in the purification of sugar and in the manufacture of dye stuffs.
6. What is the hemihydrate of calcium sulphate commonly known as?
[A] Gypsum
[B] Plaster of Paris
[C] Chloroform
[D] Limestone
Show Answer
Correct Answer: B [Plaster of Paris]
Notes:
Plaster of Paris is the common name of calcium sulphate hemihydrate because half molecule of water is attached with calcium sulphate. The chemical formula of plaster of Paris is CaSO4.1/2H2O.
7. Which of the following is the composition of vinegar?
[A] 65-75% solution of acetic acid in water
[B] 45-60% solution of acetic acid in water
[C] 28-35% solution of acetic acid in water
[D] 5-8% solution of acetic acid in water
Show Answer
Correct Answer: D [5-8% solution of acetic acid in water]
Notes:
5-8% solution of acetic acid in water is called vinegar and is used widely as a preservative in pickles
8. Which of these is NOT a compound of carbon?
[A] Acetic acid
[B] Chloroform
[C] Caustic Soda
[D] Methane
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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.
9. What is an alloy of mercury with some other metal generally known as?
[A] Galinston
[B] Amalgam
[C] Megalium
[D] Yellow metal
Show Answer
Correct Answer: B [Amalgam]
Notes:
Amalgam is the general name given to an alloy of mercury with some other metal. It can be a solid, liquid or a soft paste depending on the composition of the constituents.
10. Who gave the law of octaves for arrangement of elements?
[A] Lothar Meyer
[B] Dmitri Mendeleev
[C] John Alexander Newlands
[D] Johann Dobereiner
Show Answer
Correct Answer: C [John Alexander Newlands]
Notes:
Newland law of octaves states that If the elements are arranged in order of their increasing atomic weights, every 8th element had similar properties to the first one. It was similar as the first and eighth note in music.
