Here are 50 sample MCQs of Chemistry for learning purposes and preparing for various entry tests.
1. What happens to the rate of forward and backward reactions when a chemical equilibrium is reached?
A) Both rates become zero
B) The forward rate is greater than the backward rate
C) The forward rate is equal to the backward rate
D) The backward rate is greater than the forward rate
2. Le Chatelier’s Principle states that if a system at equilibrium is disturbed, it will tend to:
A) Decrease the temperature
B) Shift to the right to relieve the stress
C) Increase the concentration of products
D) Maintain the equilibrium constant
3. Which of the following factors does not affect the equilibrium constant?
A) Temperature
B) Pressure
C) Concentration
D) Catalyst
4. In the equilibrium reaction: N2(g) + 3H2(g) ⇌ 2NH3(g), an increase in the concentration of N2 will:
A) Increase the concentration of NH3
B) Decrease the concentration of NH3
C) Have no effect on the concentration of NH3
D) Increase the concentration of H2
5. Which of the following is a strong acid?
A) CH3COOH
B) H2SO3
C) HCl
D) H2CO3
6. The pH value of a neutral solution is:
A) 0
B) 7
C) 14
D) -7
7. Which of the following is a weak base?
A) NaOH
B) KOH
C) NH3
D) Ca(OH)2
8. What happens when an acid reacts with a metal carbonate?
A) Formation of salt and water
B) Formation of salt, water, and carbon dioxide
C) Formation of salt and carbon dioxide
D) Formation of salt and hydrogen gas
9. Alkanes are hydrocarbons that contain:
A) Only single bonds
B) Only double bonds
C) Both single and double bonds
D) Only triple bonds
10. Which of the following is the general formula of alkenes?
A) CnH2n+2
B) CnH2n
C) CnH2n-2
D) CnH2n-4
11. Ethene is an example of:
A) Alkane
B) Alkene
C) Alkyne
D) Aromatic hydrocarbon
12. What is the general formula of alkanes?
A) CnH2n
B) CnH2n+2
C) CnH2n-2
D) CnH2n-4
13. Which of the following is an unsaturated hydrocarbon?
A) Methane
B) Ethane
C) Ethene
D) Propane
14. The process of breaking down long-chain hydrocarbons into smaller, more useful molecules is called:
A) Substitution
B) Isomerization
C) Cracking
D) Polymerization
15. Which biomolecule is the main source of energy for living organisms?
A) Proteins
B) Carbohydrates
C) Lipids
D) Nucleic acids
16. Enzymes are:
A) Lipids
B) Proteins
C) Carbohydrates
D) Nucleic acids
17. The basic unit of a protein is:
A) Nucleotide
B) Amino acid
C) Glucose
D) Fatty acid
18. Which of the following gases is not a major component of the Earth’s atmosphere?
A) Oxygen
B) Nitrogen
C) Carbon dioxide
D) Helium
19. What is the primary cause of the greenhouse effect?
A) Ozone depletion
B) Methane emissions
C) Carbon dioxide emissions
D) Nitrous oxide emissions
20. The ozone layer is located in which region of the Earth’s atmosphere?
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Thermosphere
21. Hard water is characterized by the presence of high concentrations of:
A) Calcium and magnesium ions
B) Sodium and potassium ions
C) Chloride and sulfate ions
D) Nitrate and phosphate ions
22. Water pollution caused by the addition of detergents can lead to:
A) Eutrophication
B) Acid rain
C) Global warming
D) Ozone depletion
23. The process of removing salt from seawater to obtain fresh water is called:
A) Desalination
B) Distillation
C) Filtration
D) Sedimentation
24. The presence of coliform bacteria in water indicates:
A) Pollution by industrial waste
B) Pollution by organic matter
C) Pollution by radioactive substances
D) Pollution by heavy metals
25. The main cause of thermal pollution in water bodies is:
A) Industrial waste discharge
B) Agricultural runoff
C) Nuclear accidents
D) Discharge of hot water from power plants
26. Acid rain is mainly caused by the emission of:
A) Sulfur dioxide and nitrogen oxides
B) Carbon dioxide and methane
C) Chlorofluorocarbons
D) Particulate matter
27. Which of the following is a source of non-point water pollution?
A) Industrial effluents
B) Sewage treatment plants
C) Runoff from agricultural fields
D) Oil spills
28. Biochemical oxygen demand (BOD) is a measure of:
A) The amount of oxygen required for respiration by aquatic organisms
B) The amount of oxygen produced during photosynthesis
C) The amount of oxygen dissolved in water
D) The amount of oxygen consumed by decomposing organic matter in water
29. The process of adding chlorine to water to kill harmful bacteria and pathogens is called:
A) Filtration
B) Coagulation
C) Sedimentation
D) Chlorination
30. The major anthropogenic source of mercury pollution in water bodies is:
A) Industrial discharge
B) Agricultural runoff
C) Deforestation
D) Domestic sewage
31. Which of the following substances is a primary pollutant of water bodies due to its excessive use in fertilizers?
A) Phosphorus
B) Nitrogen
C) Potassium
D) Calcium
32. The term “eutrophication” refers to:
A) The increase in water temperature due to human activities
B) The process of removing dissolved salts from water
C) The excessive growth of algae in water bodies due to nutrient pollution
D) The accumulation of heavy metals in aquatic organisms
33. Which of the following is not a method of water purification?
A) Chlorination
B) Sedimentation
C) Decantation
D) Distillation
34. What is the main objective of sewage treatment plants?
A) To remove dissolved salts from wastewater
B) To remove heavy metals from wastewater
C) To remove organic matter and harmful microorganisms from wastewater
D) To remove suspended solids from wastewater
35. The process of removing large suspended particles from water by allowing them to settle at the bottom of a tank is called:
A) Chlorination
B) Filtration
C) Coagulation
D) Sedimentation
36. The presence of which of the following ions in drinking water can lead to dental fluorosis?
A) Chloride ions
B) Fluoride ions
C) Nitrate ions
D) Sulfate ions
37. Which of the following diseases is not transmitted through contaminated water?
A) Cholera
B) Typhoid
C) Malaria
D) Dysentery
38. The main cause of groundwater pollution is:
A) Industrial discharge
B) Agricultural runoff
C) Oil spills
D) Sewage leakage
39. Which of the following is not a method of controlling water pollution?
A) Recycling wastewater
B) Treating wastewater before discharge
C) Discharging untreated wastewater directly into water bodies
D) Implementing strict regulations on industrial waste disposal
40. The process of breaking down harmful substances in water into less harmful or non-toxic compounds is called:
A) Filtration
B) Oxidation
C) Bioremediation
D) Sedimentation
41. The pH of natural rainwater is around:
A) 5.5
B) 7
C) 9
D) 11
42. The substance responsible for the depletion of the ozone layer is:
A) Chlorofluorocarbons (CFCs)
B) Sulfur dioxide
C) Nitrogen oxides
D) Carbon monoxide
43. Which of the following is not a greenhouse gas?
A) Carbon dioxide
B) Methane
C) Nitrous oxide
D) Oxygen
44. Acid rain can cause damage to:
A) Buildings and monuments
B) Aquatic ecosystems
C) Agricultural crops
D) All of the above
45. The layer of the Earth’s atmosphere where most weather phenomena occur is the:
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Thermosphere
46. What is the most abundant gas in the Earth’s atmosphere?
A) Nitrogen
B) Oxygen
C) Carbon dioxide
D) Argon
47. Which of the following pollutants is a major contributor to smog formation?
A) Carbon monoxide
B) Sulfur dioxide
C) Nitrogen oxides
D) Lead
48. The process by which plants release water vapor into the atmosphere is called:
A) Condensation
B) Transpiration
C) Precipitation
D) Evaporation
49. The primary source of carbon monoxide emissions is:
A) Automobiles
B) Power plants
C) Industrial processes
D) Deforestation
50. The process by which carbon dioxide is removed from the atmosphere and stored in the oceans or plants is called:
A) Photosynthesis
B) Respiration
C) Combustion D) Carbon sequestration
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