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 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.
2. Calamine is an ore of which among the following?
[A] Zinc
[B] Copper
[C] Mercury
[D] Iron
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Correct Answer: A [Zinc]
Notes:
Calamine is an ore that contains zinc carbonate along with impurities like iron oxide. Through smelting, the zinc carbonate in calamine can be reduced to extract pure zinc metal. Other common zinc ores are sphalerite (zinc sulfide) and smithsonite (zinc carbonate). So calamine is considered a zinc ore due to its zinc carbonate content.
3. What are Sodium Alkyl Sulphate and Benzene Sulphate examples of?
[A] Explosives
[B] Insecticides
[C] Fungicides
[D] Synthetic Detergents
Show Answer
Correct Answer: D [Synthetic Detergents]
Notes:
Sodium Alkyl Sulphate and Benzene Sulphate are typical examples of Synthetic Detergents. Synthetic detergents are man-made cleansing agents that function similarly to soap. These compounds were developed during World War II when a shortage of natural oils led to a search of alternative substances. The advanced features of synthetic detergents include improved cleansing efficacy, resistance to water hardness, and the ability to function in acidic conditions.
4. Which among the following suspension in water is often called milk of magnesia because of its milk-like appearance?
[A] Magnesium Carbonate
[B] Magnesium Hydroxide
[C] Magnesium Lactate
[D] Magnesium Oxide
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Correct Answer: B [Magnesium Hydroxide]
Notes:
Magnesium Hydroxide in water is often called milk of magnesia because of its milk-like appearance. Magnesium hydroxide is the inorganic compound and occurs in nature as the mineral brucite.
5. Which among the following acid is used to ascertain, whether pure Ghee has been adulterated with Vanaspati or Margarine?
[A] Sulphuric Acid
[B] Nitric Acid
[C] Hydrochloric Acid
[D] Boric Acid
Show Answer
Correct Answer: C [Hydrochloric Acid]
Notes:
The correct answer is Hydrochloric Acid. When testing for adulteration of pure ghee with vanaspati or margarine, hydrochloric acid is used because it reacts with the fats present in these substances, producing a distinct color change. This method is based on the principle that the presence of unsaturated fats in vanaspati or margarine will lead to a different reaction compared to pure ghee. Hydrochloric acid is commonly used in food testing due to its effectiveness in identifying such adulterants.
6. PAN (Peroxyacetyl nitrate) is a secondary gaseous compound found in _?
[A] Classical smog
[B] Volatile organic compound
[C] Photochemical smog
[D] Green manure
Show Answer
Correct Answer: C [ Photochemical smog]
Notes:
Third option is the correct answer
Photochemical smog is the chemical reaction of sunlight, nitrogen oxides and volatile organic compounds in the atmosphere, which leaves airborne particles and ground-level ozone.
7. Which of the following chemicals is also known as "sweet oil of vitriol"?
[A] Diethyl ether
[B] Aluminium sulphate
[C] Sulphuric acid
[D] Iron(III) sulphate
Show Answer
Correct Answer: A [ Diethyl ether]
Notes:
Diethyl ether is a colourless, highly volatile & flammable organic compound. It was earlier used for anaesthesia but after the development of non-flammable drugs, its uses as anaesthetic has been reduced.
8. Which of the following is the use of washing soda?
[A] softening of water
[B] manufacture of glass
[C] manufacture of paints
[D] All of the above
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Correct Answer: D [All of the above]
Notes:
It is used for softening of water, laundering, cleaning, manufacture of glass, soap, borax, paper, paints and textile It is also extensively used as laboratory reagent.
9. Which of the following is correct about the first ionization enthalpy of alkaline earth metals?
[A] It is higher than corresponding Group 1 metals
[B] It is lower than corresponding Group 1 metals
[C] No fix pattern exist
[D] None of the above
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Correct Answer: A [It is higher than corresponding Group 1 metals]
Notes:
The first ionization enthalpy of these metals is higher than corresponding Group 1 metals due to the small size of these elements compared to the corresponding alkali metals. The second ionization enthalpy of these metals is lower than corresponding alkali metals.
10. How many groups of p–block elements are there in the periodic table?
[A] 4
[B] 6
[C] 8
[D] 3
Show Answer
Correct Answer: B [6]
Notes:
There are six groups of p–block elements in the periodic table numbering from 13 to 18.
