1. What is the molecular formula of water?
a) H₂O₂
b) H₂O
c) HO₂
d) H₃O
Answer: b) H₂O
2. Which type of bond holds the hydrogen and oxygen atoms together in a water molecule?
a) Ionic bond
b) Covalent bond
c) Metallic bond
d) Hydrogen bond
Answer: b) Covalent bond
3. Water exhibits high surface tension due to:
a) Ionic bonding
b) Hydrogen bonding
c) Covalent bonding
d) Van der Waals forces
Answer: b) Hydrogen bonding
4. The angle between the hydrogen atoms in a water molecule is approximately:
a) 90°
b) 104.5°
c) 120°
d) 180°
Answer: b) 104.5°
5. Water has a high specific heat capacity. What is the approximate value?
a) 1 cal/g°C
b) 4.18 J/g°C
c) 4.18 cal/g°C
d) 1 J/g°C
Answer: b) 4.18 J/g°C
6. What is the boiling point of water at 1 atm pressure?
a) 90°C
b) 100°C
c) 110°C
d) 120°C
Answer: b) 100°C
7. Water is called the “universal solvent” because:
a) It dissolves only acids
b) It dissolves most substances
c) It is neutral in pH
d) It has low surface tension
Answer: b) It dissolves most substances
8. What is the pH of pure water at 25°C?
a) 6
b) 7
c) 8
d) 5
Answer: b) 7
9. Which property of water is responsible for capillary action in plants?
a) Cohesion and adhesion
b) High density
c) Low boiling point
d) Polarity only
Answer: a) Cohesion and adhesion
10. The property of water that allows insects to walk on its surface is called:
a) Viscosity
b) Surface tension
c) Capillarity
d) Polarity
Answer: b) Surface tension
11. Water is a polar molecule because:
a) Oxygen is less electronegative than hydrogen
b) It has an unequal sharing of electrons
c) It has no bond angle
d) It is linear
Answer: b) It has an unequal sharing of electrons
12. Which form of water has the highest density?
a) Ice
b) Liquid water
c) Water vapor
d) All are equal
Answer: b) Liquid water
13. The maximum density of water occurs at:
a) 0°C
b) 4°C
c) 25°C
d) 100°C
Answer: b) 4°C
14. Water has high heat of vaporization. This property is important for:
a) Cooling living organisms
b) Freezing water quickly
c) Dissolving salts
d) Increasing viscosity
Answer: a) Cooling living organisms
15. The process by which water moves through a semipermeable membrane is called:
a) Filtration
b) Osmosis
c) Diffusion
d) Evaporation
Answer: b) Osmosis
16. Water can dissolve ionic compounds because:
a) Water is non-polar
b) Water forms hydrogen bonds with ions
c) Water has high viscosity
d) Water has low heat capacity
Answer: b) Water forms hydrogen bonds with ions
17. What fraction of the Earth’s surface is covered by water?
a) 50%
b) 60%
c) 70%
d) 80%
Answer: c) 70%
18. Water expands upon freezing due to:
a) Increased kinetic energy
b) Formation of hydrogen-bonded lattice
c) Decrease in polarity
d) Decrease in molecular size
Answer: b) Formation of hydrogen-bonded lattice
19. Water has high dielectric constant. This property allows it to:
a) Resist electrical conduction
b) Dissolve salts and ions
c) Evaporate quickly
d) Freeze easily
Answer: b) Dissolve salts and ions
20. Water participates in many chemical reactions. It is often called:
a) Reactant
b) Solvent
c) Both reactant and solvent
d) Product only
Answer: c) Both reactant and solvent
21. Water’s triple point occurs when:
a) Solid, liquid, and gas coexist
b) Water boils
c) Water freezes
d) Water evaporates
Answer: a) Solid, liquid, and gas coexist
22. Which property of water helps in moderating Earth’s climate?
a) High surface tension
b) High specific heat capacity
c) Low density
d) High vapor pressure
Answer: b) High specific heat capacity
23. Which of the following is NOT a property of water?
a) Polar molecule
b) High boiling point
c) Low cohesion
d) High heat of vaporization
Answer: c) Low cohesion
24. Water can form hydrogen bonds because:
a) Oxygen has lone pairs and hydrogen is partially positive
b) It is non-polar
c) Hydrogen is negatively charged
d) Oxygen has no electrons
Answer: a) Oxygen has lone pairs and hydrogen is partially positive
25. Water vapor in the air contributes to:
a) Humidity
b) Freezing
c) Salinity
d) Viscosity
Answer: a) Humidity
26. Water shows high adhesion. Which phenomenon is caused by this property?
a) Ice floating
b) Capillary rise
c) Low boiling point
d) Evaporation
Answer: b) Capillary rise
27. The latent heat of fusion of water is approximately:
a) 80 cal/g
b) 540 cal/g
c) 100 cal/g
d) 334 cal/g
Answer: d) 334 cal/g
28. Which of the following is a physical property of water?
a) Reacts with metals
b) Freezes at 0°C
c) Hydrolyzes esters
d) Forms oxides
Answer: b) Freezes at 0°C
29. Water is essential for life primarily because:
a) It has low density
b) It is a universal solvent and participates in reactions
c) It boils at 50°C
d) It is non-polar
Answer: b) It is a universal solvent and participates in reactions
30. Ice floats on water because:
a) Ice is denser than water
b) Ice has a lower density than water
c) Ice melts at high temperature
d) Water is heavier than ice
Answer: b) Ice has a lower density than water