Chapter 1 - "States of Matter" - Long Questions
Chapter 1 - "States of Matter" - Long Questions:-
Question 1 (5 marks)Describe the arrangement, movement, and energy of particles in solids, liquids, and gases. Use particle theory in your explanation.
Answer:
In a solid, particles are closely packed in a regular and fixed arrangement. They have strong forces of attraction between them and can only vibrate about fixed positions. The particles have low kinetic energy.
In a liquid, particles are still close together but arranged randomly. The forces of attraction are weaker than in solids, allowing particles to move and slide past one another. Liquids have more kinetic energy than solids but less than gases.
In a gas, particles are far apart with very weak forces of attraction. They move rapidly and randomly in all directions. Gas particles have the highest kinetic energy of the three states.
Question 2 (5 marks)
Explain why gases are easily compressed but liquids and solids are not.
Answer:
Gases are easily compressed because there are large spaces between gas particles. When pressure is applied, these particles can be pushed closer together without significant resistance.In liquids, particles are already close together with very little empty space between them. This makes liquids difficult to compress. In solids, particles are tightly packed in fixed positions with strong forces of attraction, leaving almost no space for compression. Therefore, solids are practically incompressible.
Question 3 (5 marks)
Describe what happens to particles when a solid is heated until it becomes a gas.
Answer:
When a solid is heated, its particles gain kinetic energy and vibrate more vigorously. As heating continues, the particles gain enough energy to overcome some of the forces of attraction holding them in fixed positions, causing the solid to melt into a liquid.With further heating, liquid particles gain even more kinetic energy and move faster. Eventually, they overcome the remaining forces of attraction and escape from the liquid to form a gas. In the gas state, particles move freely and are far apart.
Question 4 (5 marks)
Explain evaporation using the kinetic particle theory and state why evaporation causes cooling.
Answer:
Evaporation occurs when some particles at the surface of a liquid gain enough kinetic energy to escape into the gas phase. These particles have higher energy than the average particle in the liquid.When high-energy particles leave the liquid, the average kinetic energy of the remaining particles decreases. As temperature is a measure of average kinetic energy, the liquid cools down. This is why evaporation causes cooling and can occur at any temperature.
Question 5 (5 marks)
Describe diffusion in gases and explain why it happens faster in gases than in liquids.
Answer:
Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. In gases, particles move rapidly and randomly in all directions.Gas particles are far apart and have high kinetic energy, allowing them to spread quickly. In liquids, particles move more slowly and are closer together, which slows down diffusion. As a result, diffusion occurs much faster in gases than in liquids.
Question 6 (5 marks)
Explain what happens to particle motion and energy during melting.
Answer:
During melting, a solid absorbs heat energy from its surroundings. This energy is used to overcome the forces of attraction between particles rather than increasing temperature.The particles gain energy and vibrate more until they break free from their fixed positions. Once melted, the particles are able to move past each other, forming a liquid. The temperature remains constant during melting because the energy is used to change the state, not to increase kinetic energy.
Question 7 (5 marks)
Explain condensation using particle theory and changes in energy.
Answer:
Condensation occurs when a gas cools and changes into a liquid. As gas particles lose kinetic energy, they move more slowly.The particles come closer together as forces of attraction become stronger. Eventually, the particles form a liquid where they are close together but still able to move past one another. Energy is released to the surroundings during condensation.
Question 8 (5 marks)
A balloon shrinks when placed in a freezer. Explain this observation using particle theory.
Answer:
When the balloon is placed in a freezer, the gas particles inside lose kinetic energy. As a result, the particles move more slowly.Because the particles move less vigorously, they collide with the walls of the balloon less frequently and with less force. This reduces the pressure inside the balloon, causing it to shrink as the gas occupies a smaller volume.
Question 9 (5 marks)
Explain why the temperature stays constant during boiling even though heat is supplied.
Answer:
During boiling, heat energy is supplied to the liquid, but the temperature remains constant. This is because the energy is used to overcome the forces of attraction between particles rather than increasing their kinetic energy.The particles gain enough energy to change from the liquid state to the gas state. As a result, the temperature does not rise until all the liquid has boiled and changed into gas.
Question 10 (5 marks)
Describe and explain the changes in particle arrangement and energy when a gas is cooled until it becomes a solid.
Answer:
When a gas is cooled, its particles lose kinetic energy and move more slowly. The particles come closer together and condense to form a liquid.With further cooling, liquid particles lose more energy and the forces of attraction become strong enough to hold them in fixed positions. The liquid freezes to form a solid. In the solid state, particles have low kinetic energy and only vibrate about fixed positions.
Question 11 (5 marks)
Describe what happens to particles during melting.
Answer:
When a solid is heated, its particles gain kinetic energy and vibrate more strongly. At the melting point, the energy supplied is used to overcome the forces of attraction between particles. The particles break free from their fixed positions and begin to move past each other, forming a liquid.
Question 12 (5 marks)
Explain evaporation using the kinetic particle theory.
Answer:
Evaporation occurs when some particles at the surface of a liquid gain enough kinetic energy to escape into the gas state. These high-energy particles leave the liquid, reducing the average kinetic energy of the remaining particles. As a result, the temperature of the liquid decreases.
Question 13 (5 marks)
Explain why evaporation causes cooling.
Answer:
During evaporation, the fastest and most energetic particles leave the liquid. This lowers the average kinetic energy of the remaining particles. Since temperature depends on average kinetic energy, the liquid cools down.
Question 14 (5 marks)
State Boyle’s Law and explain it using particle theory.
Answer:
Boyle’s Law states that for a fixed mass of gas at constant temperature, pressure is inversely proportional to volume. When a gas is compressed, particles are forced closer together and collide with the container walls more frequently. This increases pressure.
Question 15 (5 marks)
Explain what happens to gas pressure when volume decreases at constant temperature.
Answer:
When volume decreases, gas particles are confined to a smaller space. They collide with the walls of the container more often. This increases the pressure exerted by the gas.
Question 16 (5 marks)
State Charles’s Law and explain it using particle theory.
Answer:
Charles’s Law states that the volume of a gas is directly proportional to its absolute temperature at constant pressure. When temperature increases, gas particles gain kinetic energy and move faster. This causes them to spread out and occupy a larger volume.
Question 17 (5 marks)
State the pressure law and explain it.
Answer:
The pressure law states that the pressure of a gas is directly proportional to its absolute temperature at constant volume. An increase in temperature increases particle speed, leading to more frequent collisions and higher pressure.
Question 18 (5 marks)
Describe the Combined Gas Law.
Answer:
The Combined Gas Law combines Boyle’s Law and Charles’s Law. It shows the relationship between pressure, volume, and temperature for a fixed mass of gas. A change in one variable affects the others.
Question 19 (5 marks)
State the Ideal Gas Equation and explain each term.
Answer:
The Ideal Gas Equation is PV = nRT. P represents pressure, V is volume, n is the number of moles of gas, R is the gas constant, and T is temperature in Kelvin. The equation relates all gas variables in one expression.
Question 20 (5 marks)
Explain how volume changes when pressure increases and temperature decreases.
Answer:
Increasing pressure forces gas particles closer together, reducing volume. Decreasing temperature lowers particle kinetic energy, also reducing volume. Together, both changes cause a significant decrease in gas volume.
Question 21 (5 marks)
The graph shows the relationship between pressure and volume for a fixed mass of gas at constant temperature. Describe and explain the graph.
Answer:
The graph shows that as the volume of the gas increases, the pressure decreases. This is an inverse relationship. When the gas is compressed into a smaller volume, gas particles are closer together and collide with the walls of the container more frequently. These frequent collisions increase the pressure. When the volume increases, collisions become less frequent, so pressure decreases.
Question 22 (5 marks)
The graph shows how the volume of a gas changes with temperature at constant pressure. Explain the shape of the graph using particle theory.
Answer:
The graph is a straight line showing that volume increases as temperature increases. As temperature rises, gas particles gain kinetic energy and move faster. The particles spread further apart, causing the gas to occupy a larger volume. This direct relationship explains the straight-line graph.
Question 23 (5 marks)
Explain how breathing in humans depends on gas laws and particle movement
Answer:
During inhalation, the volume of the lungs increases. This causes the pressure inside the lungs to decrease. Air then moves from the higher pressure outside into the lungs. During exhalation, lung volume decreases, pressure increases, and air is forced out. These changes are explained by Boyle’s Law and the movement of gas particles.
Question 24 (5 marks)
Aerosol cans are labelled “Do not expose to heat.” Explain why heating an aerosol can is dangerous.
Answer:
When an aerosol can is heated, the gas particles inside gain kinetic energy and move faster. Since the volume of the can is fixed, the pressure increases as particles collide more frequently and forcefully with the walls. If the pressure becomes too high, the can may explode.
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