Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. The Helium atoms that have lost two electrons are called ________?
[A] Alpha rays
[B] Beta rays
[C] Gamma rays
[D] None of the above
Show Answer
Correct Answer: A [Alpha rays]
Notes:
Helium atoms that have lost two electrons are called alpha rays. Alpha rays are also called alpha particles or alpha radiation. Alpha particles are made up of two protons and two neutrons bound together into a particle that is identical to a helium-4 nucleus.
Alpha particles are named after the first letter in the Greek alphabet, α. They were the first nuclear radiation to be discovered.
When a helium atom loses its electrons, it is left with only the nucleus. This is called an alpha particle.
2. How many noble gases occur naturally?
[A] Three
[B] Four
[C] Five
[D] Six
Show Answer
Correct Answer: D [Six]
Notes:
Noble gases are characterized by their low reactivity. The reason for this is their full electron shell, which makes them very stable and unlikely to engage in chemical reactions. The six noble gases that occur naturally are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn). Despite the inertness of noble gases, some of them like Xenon are known to form compounds.
3. 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.
4. If a baby diaper is subjected to different solutions, which of the following will it absorb the maximum quantity of?
[A] Distilled Water
[B] Drinking Water
[C] Hard Water
[D] Urine
Show Answer
Correct Answer: A [Distilled Water]
Notes:
A baby diaper can absorb the maximum quantity of distilled water as it lacks impurities such as minerals and ions that are present in other type of water. The absorbent materials in diapers, often polymers called sodium polyacrylate, can hold up to 30 times their weight in distilled water, making them highly efficient.
5. L.P.G. is a hydrocarbon consisting of a mixture of :
[A] Methane and Butane
[B] Propane and Butane
[C] Ethane and Propane
[D] Ethane and Butane
Show Answer
Correct Answer: B [Propane and Butane]
Notes:
L.P.G. (Liquefied Petroleum Gas) primarily consists of propane and butane. It is used as fuel for heating, cooking, and vehicles. Propane (C3H8) and butane (C4H10) are both byproducts of natural gas processing and petroleum refining. LPG is favored for its high energy content and clean-burning properties.
6. Consider the following:
- Hydrogen (H2)
- Carbon monoxide (CO)
- Carbon dioxide (CO2)
- Methane (CH4)
Which of the above is/are component(s) of high-quality (100% pure) Syngas?
[A] 1 Only
[B] 1 & 2 Only
[C] 1, 2 & 3 Only
[D] 1, 2, 3 & 4
Show Answer
Correct Answer: B [ 1 & 2 Only]
Notes:
The high-quality (100% Pure) Syngas has the main components of (H2 + CO)
7. 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
Show Answer
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.
8. What do we call the compounds having identical molecular formula but different structures?
[A] Functional isomers
[B] Structural isomers
[C] Mirror isomers
[D] Branched isomers
Show Answer
Correct Answer: B [Structural isomers]
Notes:
The compounds with identical molecular formula but different structures are called structural isomers.
9. Choose the incorrect ‘Alloy – constituent metal’ pair:
[A] Lockalloy – Iron
[B] Vitallium – Cobalt
[C] Italma – Aluminium
[D] Constantan – Copper
Show Answer
Correct Answer: A [Lockalloy – Iron]
Notes:
Lockalloy is an alloy that contains 62% beryllium and 38% aluminum. All other pairs are correctly matched.
10. Which of these ores is not an oxide?
[A] Sphalerite
[B] Haematite
[C] Cuprite
[D] Magnetite
Show Answer
Correct Answer: A [Sphalerite]
Notes:
Sphalerite (ZnS) is a sulphide. All others are oxides. Haematite and Magnetite are the oxides of iron and Cuprite is an oxide of Copper.
