Understanding Substances and Mixtures

What is a pure substance?

• A pure substance is a material with a uniform and definite composition, consisting of only one type of particle.

• A pure substance has varying composition depending on its environment.

• A pure substance is always a liquid or gas.

• A pure substance can contain multiple types of particles.

Define a mixture.

• A mixture is a solution that dissolves completely.

• A mixture is a chemical reaction between two substances.

• A mixture is a combination of two or more substances.

• A mixture is a single substance with uniform composition.

Give an example of a homogeneous mixture.

• Air

• Salt and water

• Sand

• Oil in water

How can one separate pebbles from rice?

• Centrifugation

• Threshing

• Handpicking

• Filtration

How can we separate naphthalene and salt?

• Decantation

• Sublimation

• Filtration

• separating funnel

Describe the process of evaporation.

• Evaporation occurs when water vapor condenses into liquid.

• Evaporation is the process of freezing water into ice.

• Evaporation is the transformation of liquid water into water vapor due to energy absorption.

• Evaporation is the mixing of water with other liquids.

How does winnowing work in separating mixtures?

• Winnowing separates materials based on their color rather than weight.

• Winnowing involves mixing materials to create a uniform blend.

• Winnowing uses heat to melt heavier materials away from lighter ones.

• Winnowing works by using air to separate lighter materials from heavier ones in a mixture.

What is the role of sedimentation in separation techniques?

• Sedimentation aids in separating solid particles from fluids based on density and size.

• Sedimentation is used to increase the temperature of fluids.

• Sedimentation is a technique for filtering air pollutants.

• Sedimentation helps in mixing different types of fluids together.

What is magnetic separation and when is it applicable?

• Magnetic separation is a technique used to separate magnetic materials from non-magnetic materials.

• A method to enhance magnetic properties of materials

• A technique for separating liquids based on density

The process of intermixing of particles on their own as they get into each other's spaces is called-