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 of the following is also known as wood alcohol?
[A] Methanol
[B] Ethanol
[C] Propanal
[D] Butanol
Show Answer
Correct Answer: A [Methanol]
Notes:
Methanol (CH3OH) is also known as Wood Alcohol. It’s a solvent in many chemical processes and is a component of automobile antifreeze.
2. Which among the following oxides cause the Acid rain?
[A] Carbon monoxide and carbon dioxide
[B] Nitrous oxide and sulphur dioxide
[C] Carbon dioxide and nitrous oxide
[D] Sulphur dioxide and carbon monoxide
Show Answer
Correct Answer: B [Nitrous oxide and sulphur dioxide ]
Notes:
Acid rain is caused by nitrous oxides (NOx) and sulfur dioxide (SO2) emissions, which react with water molecules in the atmosphere to form nitric and sulfuric acids. These acids then fall to the ground in rain, snow, fog, or dust particles.
3. Which among the following scientists had discovered Radium?
[A] Marie and Pierre Curie
[B] Andre-Louis Debierne
[C] Kasimir Fajans
[D] Oswald Helmuth Gohring
Show Answer
Correct Answer: A [Marie and Pierre Curie]
Notes:
Radium(Ra) with atomic number 88 was discovered by Marie and Pierre Curie in 1898 as Radium Chloride. However, it was Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne through the electrolysis of radium chloride in 1911.
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 basic atoms are must in an Alkaloid?
[A] Sodium
[B] Nitrogen
[C] Magnesium
[D] Potassium
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Correct Answer: B [Nitrogen]
Notes:
Alkaloids are a class of naturally occurring organic compounds that mostly contain basic nitrogen atoms. Nitrogen is essential in their structure, contributing to their pharmacological properties. Common examples of alkaloids include morphine, caffeine, and nicotine, all of which contain nitrogen. Sodium, magnesium, and potassium are not fundamental components of alkaloids.
6. Which among the following will undergo a chemical reaction depending on the pH of the solution?
[A] Calcium Oxide
[B] Zinc Oxide
[C] Ferric Oxide
[D] Ferrous Oxide
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Correct Answer: B [Zinc Oxide]
Notes:
Zinc oxide (ZnO) can undergo a chemical reaction depending on the pH of the solution. In acidic conditions, it can react to form zinc ions (Zn²⁺), while in alkaline conditions, it can form zincates. This behavior is due to its amphoteric nature, which allows it to react with both acids and bases. In contrast, calcium oxide (CaO) is basic, ferric oxide (Fe₂O₃) is generally inert in neutral pH, and ferrous oxide (FeO) is less reactive in varying pH levels.
7. Which among the following kinds of Chemical reactions cause the rocks turn red or yellowish?
[A] Hydration
[B] Oxidation
[C] Carbonation
[D] Exfoliation
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Correct Answer: B [Oxidation]
Notes:
The correct answer is Oxidation. This reaction occurs when minerals in rocks, particularly iron-bearing minerals, react with oxygen. This process can lead to the formation of iron oxides, which give rocks a reddish or yellowish hue. For example, rusting of iron in rocks is a common oxidation reaction. Oxidation is a important weathering process, contributing to soil formation and landscape changes.
8. 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
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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.
9. Which of the following element has the highest first ionization enthalpy?
[A] Magnesium
[B] Strontium
[C] Beryllium
[D] Barium
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Correct Answer: C [Beryllium]
Notes:
The alkaline earth metals have low ionization enthalpies due to fairly large size of the atoms. Since the atomic size increases down the group, their ionization enthalpy decreases.
10. What happens to the non-metallic character of elements in the p-block of the periodic table?
[A] non-metallic character decreases down the group
[B] non-metallic character increases down the group
[C] No fix pattern
[D] None
Show Answer
Correct Answer: A [non-metallic character decreases down the group]
Notes:
The non-metallic character of elements decreases down the group. In fact, the heaviest element in each p-block group is the most metallic in nature.