Chemistry MCQ Quiz - Objective Question with Answer for Chemistry - Download Free PDF
Last updated on Jun 13, 2025
Latest Chemistry MCQ Objective Questions
Chemistry Question 1:
Which one of the following nitrogen oxides may dimerize?
Answer (Detailed Solution Below)
Chemistry Question 1 Detailed Solution
CONCEPT:
Dimerization of Nitrogen Oxides
- Some nitrogen oxides can undergo dimerization under specific conditions to form stable dimers.
- Dimerization usually occurs when the monomer has an unpaired electron or is a free radical. This allows the molecules to pair up and stabilize by forming a covalent bond or through other interactions.
EXPLANATION:
- NO₂ (Nitrogen dioxide): This molecule has an unpaired electron, making it a free radical. As a result, it can dimerize to form N₂O₄ (dinitrogen tetroxide) under suitable conditions, such as low temperatures.
Therefore, the nitrogen oxide that may dimerize is NO₂.
Reaction for dimerization of NO₂:
2NO₂ → N₂O₄
Chemistry Question 2:
Which of the following vitamin is most easily destroyed vitamin while cooking?
Answer (Detailed Solution Below)
Chemistry Question 2 Detailed Solution
The correct answer is Vitamin C.
Concept:
- Vitamins are organic substances that we need in sufficient quantities to maintain good health.
- Our body, however, cannot synthesize them. Therefore, we need to consume natural sources such as fruits and vegetables.
- Vitamins are divided into two groups– water-soluble vitamins (Vitamins of B group and Vitamin C) and fat-soluble vitamins (Vitamins A, D, E, and K).
Explanation:
- Vitamin C is the vitamin that is destroyed by heat during cooking.
- When we boil something that contains vitamin C, it reduces its content more than any other method of cooking.
- Broccoli, spinach, and lettuce, for example, lose up to or more than 50% of their vitamin C when they are cooked.
- Water-soluble vitamins are also temperature-sensitive vitamins.
- When the temperature drops below 86°F, vitamin C begins to denature.
- Vitamin C is primarily found in oranges, strawberries, tomatoes, broccoli, and green peppers, among other fruits and vegetables.
- When vitamin C is exposed to air, it is easily destroyed, which is what happens when food is overheated.
- When fat-soluble vitamins are heated or exposed to air, they are not destroyed.
Chemistry Question 3:
Which of the following vitamin is tocopherol?
Answer (Detailed Solution Below)
Chemistry Question 3 Detailed Solution
The correct answer is E.
Key Points
- Vitamin E is tocopherol.
- Vitamin E represents a group of compounds that contain both tocopherol and tocotrienol.
- It is good for the immune system and it fights toxins.
- It is a fat-soluble vitamin.
- It is a very powerful antioxidant.
- Weak muscles and fertility problems are signs of deficiency of vitamin E.
- Its deficiency also causes hair damage and skin problems.
Important Points
Name of Vitamin | Chemical Name |
A | Retinol |
B1 | Thiamine |
B2 | Riboflavin |
B12 | Cyanocobalamin |
C | Ascorbic acid |
D | Ergocalciferol, Cholecalciferol |
K | Phylloquinone |
Chemistry Question 4:
Consider the following reactions
A + NaCl + H2SO4 \(\rightarrow\) CrO2 Cl2 + Side Products
Little
amount
CrO2 Cl2(Vapour) + NaOH → B + NaCl + H2O
B + H+ → C + H2 O
The number of terminal 'O' present in the compound 'C' is _________.
Answer (Detailed Solution Below) 6
Chemistry Question 4 Detailed Solution
CONCEPT:
Terminal Oxygen Atoms in Chemical Compounds
- Terminal Oxygen Atoms: These are oxygen atoms that are at the end of a bond or functional group, typically attached to a central atom (like chromium in this case) and are not involved in further bonding.
- Chemical Reactions: The reactions provided involve chromium compounds, where the terminal oxygen atoms come from the formation of the dichromate ion (Cr₂O₇²⁻) in the final compound.
EXPLANATION:
\(\mathrm{Cr}_2\mathrm{O}_7^{2-} + \mathrm{NaCl} + \mathrm{H}_2\mathrm{SO}_4 \rightarrow \mathrm{CrO}_2\mathrm{Cl}_2 \\ \mathrm{CrO}_2\mathrm{Cl}_2 (\text{Vapour}) + \mathrm{NaOH} \rightarrow \mathrm{Na}_2\mathrm{CrO}_4 + \mathrm{NaCl} + \mathrm{H}_2\mathrm{O} \\ \mathrm{Na}_2\mathrm{CrO}_4 + \mathrm{H}^{\oplus} \rightarrow \mathrm{Na}_2\mathrm{Cr}_2\mathrm{O}_7 + \mathrm{H}_2\mathrm{O} \\ \hspace{8cm} (C) \\ \mathrm{Na}_2\mathrm{Cr}_2\mathrm{O}_7 \rightarrow 2\mathrm{Na}^{\oplus} + \mathrm{Cr}_2\mathrm{O}_7^{2-}\)No of terminal "O" = 6
Therefore, the correct answer is: The number of terminal "O" present in compound C is 6.
Chemistry Question 5:
0.5 g of an organic compound on combustion gave 1.46 g of CO2 and 0.9 g of H2 O. The percentage of carbon in the compound is ____. (Nearest integer) [Given : Molar mass (in g mol–1) C : 12, H : 1, O : 16]
Answer (Detailed Solution Below) 80
Chemistry Question 5 Detailed Solution
CONCEPT:
Determining the Percentage of Carbon in an Organic Compound
%C = (mass of C in the compound / mass of the compound) × 100
- When an organic compound undergoes combustion, it reacts with oxygen to form CO2 and H2O. From the masses of CO2 and H2O produced, the percentage of carbon and hydrogen in the compound can be calculated.
- The mass of carbon in CO2 is calculated by finding the moles of CO2 produced, then multiplying by the molar mass of carbon (12 g/mol).
- The percentage of carbon in the compound is then calculated using the formula:
EXPLANATION:
- Given:
- Mass of organic compound = 0.5 g
- Mass of CO2 produced = 1.46 g
- Mass of H2O produced = 0.9 g
- To calculate the mass of carbon in the compound:
- Moles of CO2 = mass of CO2 / molar mass of CO2
- Molar mass of CO2 = 12 (for C) + 32 (for O) = 44 g/mol
- Moles of CO2 = 1.46 g / 44 g/mol = 0.03318 mol
- Since each mole of CO2 contains 1 mole of carbon, the moles of carbon in the compound are also 0.03318 mol.
- Mass of carbon = moles of carbon × molar mass of carbon = 0.03318 mol × 12 g/mol = 0.3982 g
- Now, calculate the percentage of carbon in the compound:
%C = (0.3982 g / 0.5 g) × 100 = 79.64%
Therefore, the percentage of carbon in the compound is: 80% (rounded to the nearest integer).
Top Chemistry MCQ Objective Questions
Drug which reduce fever is known as
Answer (Detailed Solution Below)
Chemistry Question 6 Detailed Solution
Download Solution PDFThe correct answer is Antipyretic.
- Antipyretic is a drug that reduces fever.
- Antipyretics cause the hypothalamus to override a prostaglandin-induced increase in temperature.
- The body then works to lower the temperature, which results in a reduction in fever.
Additional Information
- Barbiturates are a type of central nervous system (CNS) depressant used to treat insomnia, seizures, and headaches.
- Antiseptic slows or stops the growth of micro-organisms on external surfaces of the body and helps to prevent infections.
- Antibiotics include a range of powerful drugs that kill bacteria or slow their growth.
- They treat bacterial infections.
Which one of the following sodium compounds is used for softening hard water?
Answer (Detailed Solution Below)
Chemistry Question 7 Detailed Solution
Download Solution PDFThe correct answer is Na2CO3.
Key Points
- The sodium compound is used for softening hard water. Washing soda or sodium carbonate is used for removing the permanent hardness of the water.
- Washing soda has a chemical formula Na2CO3.10H2O.
- It binds calcium and magnesium molecules in water.
- Water can be softened by adding sodium carbonate (washing soda) or bypassing the water through an ion-exchange column.
- For large-scale municipal operations, a process known as the lime-soda process is used to remove Ca2+ and Mg2+ from the water supply.
Additional Information
Na2SO4 |
Sodium Sulphate Formula: Na2SO4 Molar mass: 142.04 g/mol Density: 2.66 g/cm³ Boiling point: 1,429 °C Melting point: 884 °C Soluble in: Water |
NaOH |
Sodium Hydroxide Formula: NaOH Molar mass: 39.997 g/mol Density: 2.13 g/cm³ Boiling point: 1,388 °C IUPAC ID: Sodium hydroxide, Sodium oxidanide Soluble in: Water, Ethanol, Methanol |
NaHCO3 |
Bicarbonate of Soda Formula: NaHCO₃ IUPAC ID: Sodium hydrogen carbonate Molar mass: 84.007 g/mol Density: 2.2 g/cm³ Molar entropy: 102 J/(mol⋅K) Soluble in: Water |
Which of the following vitamin is tocopherol?
Answer (Detailed Solution Below)
Chemistry Question 8 Detailed Solution
Download Solution PDFThe correct answer is E.
Key Points
- Vitamin E is tocopherol.
- Vitamin E represents a group of compounds that contain both tocopherol and tocotrienol.
- It is good for the immune system and it fights toxins.
- It is a fat-soluble vitamin.
- It is a very powerful antioxidant.
- Weak muscles and fertility problems are signs of deficiency of vitamin E.
- Its deficiency also causes hair damage and skin problems.
Important Points
Name of Vitamin | Chemical Name |
A | Retinol |
B1 | Thiamine |
B2 | Riboflavin |
B12 | Cyanocobalamin |
C | Ascorbic acid |
D | Ergocalciferol, Cholecalciferol |
K | Phylloquinone |
What is the nature of bleaching powder?
Answer (Detailed Solution Below)
Chemistry Question 9 Detailed Solution
Download Solution PDFBleaching powder by its nature is an Oxidising agent.
- Stable bleaching powder is widely used as a disinfectant in water purification, as well as in the textile and pulp and paper industries.
- "Bleaching powder" is made by the action of chloride gas on calcium hydroxide.
- The reaction being essentially:
- 2Ca (OH)2 + 2Cl2 → Ca(OCl)2 + CaCl2 + 2H2O.
- In the production of bleaching powder, slaked lime spread on the floors of large rectangular chambers of lead or concrete is exposed to chlorine gas.
- Bleaching powder, a solid combination of chlorine and slaked lime, was introduced in 1799 by Scottish chemist Charles Tennant.
Which of the following is an example of homogeneous mixtures?
Answer (Detailed Solution Below)
Chemistry Question 10 Detailed Solution
Download Solution PDFThe correct answer is Sugar in water.
Key Points
- The physical properties help in separating the homogenous mixtures.
- Those mixtures in which the substances are completely mixed together and are indistinguishable from one another are called homogeneous mixtures.
- A homogeneous mixture is a mixture in which the composition is uniform throughout the mixture.
- Many homogeneous mixtures are commonly referred to as solutions.
- Some of the examples of homogeneous mixtures (or solutions) are Sugar solution, Salt solution, Copper sulphate solution, Seawater, Alcohol and water mixture, Petrol and oil mixture, Soda water etc.
- Heterogeneous mixture:
- A heterogeneous mixture is a mixture with a non-uniform composition that contains components in different phases.
- The composition varies from one region to another with at least two phases that remain separate from each other, with clearly identifiable properties.
- Heterogeneous mixtures contain particles that retain their chemical properties when they are mixed and can be distinguished after they are mixed.
- The components of heterogeneous mixtures can be separated by the filtration of chemical procedures.
- The two types of heterogeneous mixtures are suspensions and colloids.
- Sugar and sand form a heterogeneous mixture. If you look closely, you can identify tiny sugar crystals and particles of sand.
- Ice cubes in cola form a heterogeneous mixture.
In the reaction H2O2 + Cl2 → 2HCl + O2, H2O2 acts as:
Answer (Detailed Solution Below)
Chemistry Question 11 Detailed Solution
Download Solution PDFThe correct answer is A reducing agent.
Key Points
- Hydrogen peroxide H2O2 is acting as a reducing agent here.
- A reducing agent is a compound that oxidises itself and reduces the other compound in a chemical reaction.
- A reducing agent will lose electrons in a chemical reaction, and thus get oxidized.
- Here, the charge on Chlorine (Cl) is earlier 0, but after reaction, the charge on each Cl atom is -1, this shows that it has been reduced. Thus, Hydrogen peroxide has worked as a reducing agent.
- Also, in terms of hydrogen, adding hydrogen is termed as reduction, whereas removing it is termed as oxidation. Since hydrogen is added to chlorine, chlorine is reducing, and hence we can say that Hydrogen peroxide has worked as a reducing agent.
Molarity will decrease when we _________ temperature.
Answer (Detailed Solution Below)
Chemistry Question 12 Detailed Solution
Download Solution PDFThe correct answer is Increase.
Concept:
- Molarity:
- It is defined as the moles of a solute per litres of a solution.
- It is also known as the molar concentration of a solution.
- Molality:
- It is defined as the number of moles of solute per kilogram of solvent.
- Mole fraction:
- It is the ratio of moles of a component with the total moles of solute and solvent.
- Mass%:
- It is the percentage of the mass of solute or solvent w.r.t total mass of solution.
- Formulas:
Explanation:
- Molarity depends on the volume of the solution.
- And volume is directly proportional to temperature.
- And when we increase the temperature the volume will increase.
- So the increase in volume leads to a decrease in Molarity as Molarity is inversely proportional to the volume of solution.
Additional Information
Notes:
- Normality:
- It is defined as the number of gram equivalent per litre of solution.
- Also known as equivalent concentration.
- Normality = Number of gram equivalents / [volume of solution in litres]
- Normality is inversely proportional to temperature.
- Volume is directly proportional to temperature.
- Molarity is inversely proportional to volume.
- Molarity is inversely proportional to temperature.
- Molality is not dependent on temperature.
The chief ore of aluminium is
Answer (Detailed Solution Below)
Chemistry Question 13 Detailed Solution
Download Solution PDFThe correct answer is Bauxite.Key Points
- Bauxite is an aluminium-rich sedimentary rock formed from laterite soil.
- It is found in tropical or subtropical regions.
- Bauxite is used for the production of Aluminium.
- Bauxite is a non-ferrous metallic mineral that is used in the manufacturing of aluminium.
- Bauxite is found mainly in tertiary deposits and is associated with laterite rocks.
Important Points
- Odisha is the largest bauxite-producing state in India.
- More than half of India's bauxite deposits are found in Odisha.
- Bauxite is an important mineral used in the production of aluminium.
Additional Information
Important ores:
Aluminium | Bauxite Kaolinite (a form of clay) |
Iron | Haematite Magnetite Siderite Iron pyrites |
Copper | Copper pyrites Malachite Cuprite Copper glance |
Zinc | Zinc blend/Sphalerite Calamine Zincite |
Which of the following acids is used in the purification of gold and silver?
Answer (Detailed Solution Below)
Chemistry Question 14 Detailed Solution
Download Solution PDFThe correct answer is Nitric acid.
- Nitric acid is used in the purification of gold and silver.
Key Points
- Nitric acid is used in the purification of gold. The acid mixture aqua regia, or royal water, dissolves gold and is used to purify scrap alloy containing gold.
- Aqua regia is a mixture of hydrochloric acid and nitric acid in a 3:1 ratio.
- Nitric acid is a nitrogen oxoacid of formula HNO3 in which the nitrogen atom is bonded to a hydroxy group and by equivalent bonds to the remaining two oxygen atoms.
Important Points
Acid Name | Details |
Acetic acid |
|
Maleic acid |
|
Formic acid |
|
Which of the following is NOT present in DNA?
Answer (Detailed Solution Below)
Chemistry Question 15 Detailed Solution
Download Solution PDFThe correct answer is Uracil.
Key Points
- In DNA, Adenine, Guanine, Thymine, and Cytosine are present.
- In RNA Adenine, Guanine, Cytosine, and Uracil are present.
- Uracil
- It is one of the four nucleobases in nucleic acid RNA.
- In DNA, Uracil nucleobases are replaced by thymine.
- Its formula is C4H4N2O2.
Additional Information
- Guanine
- It is one of the four main nucleobases found in the nucleic acids DNA and RNA.
- It is used to make one of the building blocks of DNA and RNA.
- Adenine
- It is also one of the four main nucleobases found in the nucleic acids DNA and RNA.
- It is part of many substances in the body that give energy to cells.
- Cytosine
- It is pyrimidine and one of the nitrogenous bases found in RNA and DNA acid for making genetic code.
- It Plays an essential role in forming base pairs by bonding with guanine.