Chemistry MCQ Questions with Answer for all Competitive Exams

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Chemistry MCQ Questions with Answer


Q51. Match List-I with List-II and select the correct answer from the codes given below:

A. Silicon carbide1. Photosynthesis
B. Carbon fiber2. Refrigerant
C. Carbon dioxide3. Artificial diamond
D. Dichloro-difluoro4. Aircraft methane

Codes: A B C D

(a)        4 3 1 2

(b)       3 4 1 2

(c)        2 3 1 4

(d)       3 2 1 4

Answer: ​(b)

Explanation: ​As a gemstone used in jewelry, silicon carbide is called “synthetic moissanite” or just “moissanite”. Moissanite is similar to diamond in several important respects it is transparent and hard. Moissanite has become popular as a diamond substitute and may be misidentified as diamond since its thermal conductivity is close to that of the diamond, more than any other diamond substitute.

The properties of carbon fibers, such as high stiffness, high tensile strength, low weight, high chemical resistance, high-temperature tolerance, and low thermal expansion, make them very popular in aerospace, civil engineering, military, and motorsports. ​​

Dichlorodifluoromethane (R-12) is a colorless gas and usually sold under the brand name Freon-12, which is a chlorofluorocarbon halo-methane (CFC), used as a refrigerant and aerosol spray propellant. ​​

In photosynthesis, solar energy is converted to chemical energy. The chemical energy is stored in the form of glucose (sugar). Carbon dioxide, water, and sunlight are used to produce glucose, oxygen, and water.

Q52. What is Rusting of Iron?

(a) Physical change

(b) Electric change

(c) Photo Chemical change

(d) None of the above

Answer: (d)

Explanation: Rusting of iron is a chemical change. Chemical changes are the changes in which a new product is formed and the properties of this new product are completely different from the base substances. The product formed by the chemical change cannot be reversed in its base matter Example Rusting of Iron, curding of Milk, cooking of food, burning of the candle, etc.

Q53. Regarding the atom of a chemical element, the magnetic quantum number refers to

(a) Orientation

(b) Shape

(c) Size

(d) Spin

Answer: (a)

Explanation: Magnetic quantum number represents the number of orbitals present in the sub-shell magnetic quantum number about the orientation of the orbital.

Q54. Which one among the following statements regarding the properties of mixtures and compounds is not correct?

​(a)​ A mixture shows the properties of its constituents but the properties of a compound are entirely different from its constituents ​

(b)​ A mixture may be homogeneous or heterogeneous but a compound is a homogeneous substance

​(c)​ The constituents of a mixture can be separated by physical methods but those of a compound cannot be separated by physical methods ​

(d)​ Energy is either absorbed or evolved during the preparation of a mixture but not in the preparation of a compound

Answer: (d)​

Explanation: The compound is always formed by absorption or evolution of energy but no energy is released or absorbed during the formation of the mixture.


Q55. The sour taste of lemon is due to the presence of which of the following?

(a) Citric acid

(b) Acetic acid

(c) Oxalic acid

(d) Formic acid

Answer: (a)

Explanation: Citric acid is found in the juice of citrus fruits such as lemons, limes, galgals and oranges. Lemon juice contains 7–10% citric acid.

Q56. Which of the following is/are not correctly matched? ​

(I)​ Absolute alcohol​–​100% ethanol

​(II) ​Power alcohol​–​90 – 95% ethanol ​

(III)​ Rectified spirit​–​5% ethanol ​

(a)​ I only

​(b) ​II only

(c)​ III only

​(d)​ II and III

Answer: (d)​

Explanation: The rectified spirit is a mixture with a composition of 95% ethanol and 5% water. Absolute alcohol is 100% concentrated ethanol. Power alcohol is a mixture of 75-80% petrol, 20-25% ethanol, and minute amounts of aromatic compounds.

Q57. Brass is an alloy of –

​(a) ​Copper and iron ​

(b)​ Zinc and iron

​(c)​ Copper and zinc

​(d) ​Iron and nickel

Answer: (c) ​

Explanation: Brass is an alloy of copper and zinc. The proportions of zinc and copper can vary between different types of brass alloys having different mechanical and electrical properties.

Q58. Baking Soda is –​

(a)​ Sodium Hydrogen Carbonate ​

(b)​ Sodium Dihydrogen Carbonate ​

(c)​ Disodium Hydrogen Carbonate ​

(d)​ Sodium Carbonate ​

(e) ​None of the above

Answer: (a) ​

Explanation: Baking soda is sodium bicarbonate with chemical formula NaHCO3. It is primarily used in baking industries as a leavening agent.

Q59. Why hard water does not give lather with soap?

​(a)​ Hard water contains calcium and magnesium ions which form a precipitate with soap ​

(b) ​Hard water contains sulfate and chloride ions which form precipitate ​

(c)​ pH of hard water is high ​

(d)​ pH of hard water is less

Answer: (a)​

Explanation: The main cause of hardness of the water in the presence of Ca or Mg ions. When hard water containing these ions is treated with soap solution it reacts to form white cruddy ppt known as scum.

Q60. In a dry cell (battery), which of the following are used as electrolytes?

(a) Ammonium chloride and Zinc chloride

(b) Sodium chloride and Calcium chloride

(c) Magnesium chloride and Zinc chloride

(d) Ammonium chloride and Calcium chloride

Answer: (a)

Explanation: A dry cell has the electrolyte immobilized as a paste, with only enough moisture in the paste to allow current to flow. The electrolyte is ammonium chloride in the form of a paste next to the zinc anode. In some more modern types of so-called ‘high power’ batteries, the ammonium chloride has been replaced by zinc chloride.

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