Matter — Nature and States

9 practice questions on Matter — Nature and States for NSEJS, with answers

Shishya's practice questions, written with AI. Each answer was checked by an automated second pass, not by a person.

1. 1.At room temperature, a substance expands to fill any container and can be easily compressed. What is the state of this substance?

   • (A)Solid
   • (B)Liquid
   • (C)Gas
   • (D)Plasma
   Show the answer and solution

   Answer: (C) Gas

   Solution: Gases have negligible intermolecular forces, so they expand to fill containers and are easily compressible, unlike solids or liquids.

   Report an error

2. 2.Which of the following correctly describes the arrangement of particles in a solid?

   • (A)Particles are far apart and move freely in all directions
   • (B)Particles are close together and vibrate about fixed positions
   • (C)Particles are close but slide past each other easily
   • (D)Particles have no definite arrangement and fill available space
   Show the answer and solution

   Answer: (B) Particles are close together and vibrate about fixed positions

   Solution: In solids, particles are closely packed in a regular arrangement. They have strong intermolecular forces that hold them in fixed positions. The particles can only vibrate about their mean positions and cannot move freely. This gives solids their definite shape and volume.

   Report an error

3. 3.The process by which a solid directly changes into a gas without passing through the liquid state is called:

   • (A)Evaporation
   • (B)Condensation
   • (C)Sublimation
   • (D)Deposition
   Show the answer and solution

   Answer: (C) Sublimation

   Solution: Sublimation is the process where a solid converts directly into gas without becoming liquid first. Common examples include dry ice (solid CO2) and camphor. Evaporation is liquid to gas, condensation is gas to liquid, and deposition is gas to solid.

   Report an error

4. 4.During the melting of ice at 0°C, heat is supplied but the temperature remains constant. This heat energy is used to:

   • (A)Increase the kinetic energy of water molecules
   • (B)Overcome the intermolecular forces between ice molecules
   • (C)Increase the potential energy of surrounding air
   • (D)Decrease the density of ice
   Show the answer and solution

   Answer: (B) Overcome the intermolecular forces between ice molecules

   Solution: During a phase change at constant temperature, the heat supplied is called latent heat. This energy is used to overcome the intermolecular forces holding the particles in fixed positions. The kinetic energy of particles remains unchanged during melting, which is why temperature stays constant.

   Report an error

5. 5.Wet clothes dry faster on a windy day than on a calm day at the same temperature. This is because wind:

   • (A)Increases the temperature of the clothes
   • (B)Decreases the boiling point of water
   • (C)Removes water vapour from near the clothes, increasing evaporation rate
   • (D)Increases the latent heat of vaporisation
   Show the answer and solution

   Answer: (C) Removes water vapour from near the clothes, increasing evaporation rate

   Solution: Evaporation is a surface phenomenon where liquid molecules escape into the air. When wind blows, it carries away the water vapour molecules from near the clothes' surface. This reduces the humidity near the clothes and creates a concentration gradient that speeds up evaporation.

   Report an error

6. 6.A gas at 27°C and 1 atm pressure occupies a volume of 5 L. If the temperature is increased to 127°C at constant pressure, what will be the new volume?

   • (A)5.83 L
   • (B)6.25 L
   • (C)6.67 L
   • (D)7.14 L
   Show the answer and solution

   Answer: (C) 6.67 L

   Solution: Using Charles's Law V₁/T₁ = V₂/T₂, with T in Kelvin: V₂ = V₁ × (T₂/T₁) = 5 × (400/300) = 5 × (4/3) = 6.67 L.

   Report an error

7. 7.A closed container holds water at 90°C. If the pressure above the water surface is gradually reduced, which of the following will occur?

   • (A)The water will freeze
   • (B)The water will start boiling below 100°C
   • (C)The evaporation rate will decrease
   • (D)The water temperature will increase automatically
   Show the answer and solution

   Answer: (B) The water will start boiling below 100°C

   Solution: The boiling point of a liquid depends on the external pressure. When pressure decreases, the boiling point also decreases. At reduced pressure, water molecules need less energy to escape, so water can boil at temperatures below 100°C. This principle is used in vacuum evaporation techniques.

   Report an error

8. 8.A substance has a fixed volume but takes the shape of its container. It is also incompressible. The substance is most likely in which state?

   • (A)Solid
   • (B)Liquid
   • (C)Gas
   • (D)Plasma
   Show the answer and solution

   Answer: (B) Liquid

   Solution: Liquids have a definite volume but no definite shape, so they take the shape of their container. Due to strong intermolecular forces compared to gases, liquids are nearly incompressible. Solids have both definite shape and volume, while gases have neither and are highly compressible.

   Report an error

9. 9.How much heat energy is required to convert 500 g of ice at 0°C completely into water at 0°C? (Latent heat of fusion of ice = 336 J/g)

   • (A)168 kJ
   • (B)336 kJ
   • (C)672 kJ
   • (D)84 kJ
   Show the answer and solution

   Answer: (A) 168 kJ

   Solution: The heat required for phase change is calculated using Q = m × L, where m is mass and L is latent heat. Here, Q = 500 g × 336 J/g = 168000 J = 168 kJ. This heat is used only to break the bonds between ice molecules, not to raise temperature.

   Report an error