Question

3. Define the following: a. Pure substance b. Mixture c. Evaporation d. Sedimentation e. Threshing e f. Hand-picking ​

Answer 1

Answer:

a)A substance that has a fixed chemical composition throughout is called a pure substance such as water, air, and nitrogen. A pure substance does not have to be of a single element or compound.

b)Mixtures are substances composed of two or more forms of matter. You can separate them by physical methods. Examples include a solution of salt and water, a mixture of sugar and water, different gases, air, etc. In any mixture, the various components do not combine through any kind of chemical changes.

c)Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase.[1] The surrounding gas must not be saturated with the evaporating substance. When the molecules of the liquid collide, they transfer energy to each other based on how they collide with each other. When a molecule near the surface absorbs enough energy to overcome the vapor pressure, it will escape and enter the surrounding air as a gas.[2] When evaporation occurs, the energy removed from the vaporized liquid will reduce the temperature of the liquid, resulting in evaporative cooling.[3]

d)Sedimentation is the process of allowing particles in suspension in water to settle out of the suspension under the effect of gravity. The particles that settle out from the suspension become sediment, and in water treatment is known as sludge.

e)Threshing” is the operation of separating the grains from the plants. These operations may be carried out in the field or on the threshing floor, by hand or with the help of animals or machines.

f)The process used to separate slightly larger particles from a mixture by hand is called handpicking. For example, stone pieces can be separated from wheat or rice by handpicking.

Explanation:

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