[G3 LSS] Particulate Nature of Matter & Diffusion

Draw a facial expression that best represents how you feel about this chapter.

Why do scientists develop models?

• To create complex equations.

• To eliminate the need for experiments.

• To simplify complex observations and make predictions.

• To create confusion in scientific discussions.

Answer explanation

Scientists develop models to simplify complex observations and make predictions, allowing them to understand and communicate scientific concepts more effectively.

Which of the following is/are characteristic of the particulate nature of matter?

• Particles are always in motion

• Particles are discrete and separate

• Particles move randomly

Answer explanation

The particulate nature of matter is characterized by particles being in constant motion, being discrete and separate, and moving randomly. All three statements accurately describe this fundamental concept.

In 1827, Robert Brown found that small particles suspended in liquid moved randomly.

In 1888, Leon Guoy discovered that particle movements were due to collision.

In 1905, Albert Einstein developed a mathematical model for Brownian motion.

What does this tell us about the scientific knowledge?

• Scientific knowledge is static and does not evolve over time.

• Science is a cumulative and collaborative process that builds on previous discoveries.

• Science is solely based on individual discoveries.

• Scientific knowledge is solely based on assumptions.

Answer explanation

The progression from Brown's observation to Einstein's model shows that scientific knowledge builds on earlier findings, highlighting that science is a cumulative and collaborative process.

You see dust flickering in the light near the curtains of the window.

Which of the following best describes why the dust particles move?

• The dust particles are attracted to the light.

• The dust is being pushed by gravity.

• The dust particles are able to move on their own.

• The dust particles collide onto the moving air particles.

Answer explanation

The dust particles move due to collisions with moving air particles, which create currents that push the dust around. This explains the flickering motion seen in the light.

Which of the following has the highest concentration of salt?

• Adding five teaspoons of salt into 100 ml of water

• Adding ten teaspoons of salt into 100 ml of water

• Adding ten teaspoons of salt into 1000 ml of water

Answer explanation

Adding ten teaspoons of salt into 100 ml of water results in a higher concentration of salt compared to the other options, as it has the most salt per unit of water.

Diffusion is the ​ (a)   movement of particles from a region of ​ (b)   concentration to a region of ​ (c)   concentration.

• higher

• lower

• net

• overall

• complete

Answer explanation

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration. This process occurs until equilibrium is reached, highlighting the terms 'higher', 'lower', and 'net'.

Which of the following is an example of diffusion in liquids?

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A drop of ink is added into water. Which of the following will be the observation after 1 h?

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• 
• 
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In which temperature of water will ink particles diffuse faster?

• Cold water because particles move slowly.

• Cold water because particles move quickly.

• Hot water because particles move slowly.

• Hot water because particles move quickly.

Answer explanation

Ink particles diffuse faster in hot water because the increased temperature causes the water molecules to move more quickly, facilitating faster movement and mixing of the ink particles.