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 the most active chemically?
[A] Chlorine
[B] Flourine
[C] Lithium
[D] Iodine
Show Answer
Correct Answer: B [Flourine]
Notes:
Fluorine is most active because it has the highest electronegativity.
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. What are the main constituents of LPG?
[A] Methane, Hexane, Ethane
[B] Methane, Butane, Propane
[C] Ethane, Pentane, Hexane
[D] Ethane, Methane, Pentane
Show Answer
Correct Answer: B [Methane, Butane, Propane]
Notes:
LPG is composed hydrocarbons containing three or four carbon atoms. The normal components of LPG thus, are propane (C3H8), butane (C4H10) and Methane (CH4). Small concentrations of other hydrocarbons may also be present.
4. 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.
5. In the E-waste generated by the Mobile Phones, which among the following metal is most abundant?
[A] Copper
[B] Silver
[C] Palladium
[D] Gold
Show Answer
Correct Answer: A [Copper]
Notes:
The sources of e-waste are faulty desktop computers, cables, printers, refrigerators, air conditioners, televisions, electronic and electrical devices. E-waste generated by the Mobile Phones are copper, silver, gold, palladium. Among them copper is found abundantly.
6. Which of the following chemicals is called Philosopher’s Wool?
[A] Brimstone
[B] Zinc oxide
[C] Magnesium hydroxide
[D] Potassium nitrate
Show Answer
Correct Answer: B [ Zinc oxide]
Notes:
The compound zinc oxide (ZnO) is called philosopher's wool. ZnO is a white powder that is insoluble in water. Zinc oxide is used as an additive in sun screens, sun lotions, in rubber manufacturing and in photocopying products. Alchemists, as part of their rituals, burn zinc in air and collect the residue, which formed into white woolly tufts. They called it Lana philosophica in Latin, meaning philosopher's wool.
7. Which of the following does not represent the Atomic number of an atom?
[A] number of protons in the nucleus of an atom
[B] number of electrons in a neutral atom
[C] number of neutrons in the nucleus of an atom
[D] None of the above
Show Answer
Correct Answer: C [number of neutrons in the nucleus of an atom]
Notes:
The number of protons present in the nucleus of an atom or the number of electrons in a neutral atom is equal to its atomic number. It is represented by Z.
8. Which of the following is an endothermic reaction?
[A] Decomposition of calcium carbonate to calcium oxide and carbon dioxide
[B] Respiration
[C] Burning of Natural gas
[D] All of the above
Show Answer
Correct Answer: A [Decomposition of calcium carbonate to calcium oxide and carbon dioxide]
Notes:
Decomposition of calcium carbonate to calcium oxide and carbon dioxide is an endothermic reaction. Respiration and Burning of Natural gas are examples of exothermic reactions.
9. What is the order of the reaction which is independent of the concentration of reactants?
[A] Zero order
[B] First order
[C] Second order
[D] Third order
Show Answer
Correct Answer: A [Zero order]
Notes:
Order of a reaction can be 0, 1, 2, 3 and even a fraction. A zero order reaction means that the rate of reaction is independent of the concentration of reactants.
10. Which of the following is / are correct statements about methane?
- The largest reservoir of methane on earth is under the permafrost at arctic and Antarctic
- Methane has a tetrahedral structure and also known as Hydrogen Carbide
- Methane can be produced by Serpentinite method
Select the correct option from codes given below:
[A] Only 1 & 2
[B] Only 1 & 3
[C] Only 2 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: C [Only 2 & 3 ]
Notes:
Methane has a tetrahedral structure, which is multiplanar, in which carbon atom lies at the centre and the four hydrogen atoms lie at the four corners of a regular tetrahedron. The largest reservoir of methane on earth is under the seafloor. Serpentinite method is a method of producing Methane by inorganic method.
