Tag: process of separating components of a mixture

Questions Related to process of separating components of a mixture

What is a chemical change?

chemistry changes around us crystallisation process of separating components of a mixture physical changes

  1. Change in size, shape

  2. Change from one substance to another new substance

  3. Change in temperature from lower to higher

  4. None of above

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Correct Option: B
Explanation:

A chemical change is a process where one or more substances are converted into one or more new substances. Examples: Explosion of fireworks that produces heat, light, sound and unpleasant gases, breaking down of ozone in the ozone layer by the UV radiations.


Hence, the correct option is $B$

Which of the following cause a substance to change into an entirely new substance with a new chemical formula?

chemistry changes around us crystallisation process of separating components of a mixture physical changes

  1. Physical change

  2. Chemical change

  3. Both A and B

  4. None of these

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Correct Option: B
Explanation:

When a substance undergoes chemical change, its chemical properties are altered.

Which of the following is not a chemical change?

chemistry changes around us crystallisation process of separating components of a mixture physical changes

  1. Whipping eggs

  2. Burning wood

  3. Digestion

  4. All of above

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Correct Option: A
Explanation:

In whipping of eggs, the air is introduced into the fluid but no new substance is formed. Hence, it is a physical change. Digestion and burning of wood results in the formation of new substances. Thus, it is a physical change.


Hence, the correct option is $\text{A}$

An example of chemical change is :
chemistry changes around us crystallisation process of separating components of a mixture physical changes

  1. water condensing on the outside of your cold beverage

  2. bending a wire

  3. slicing bread

  4. freezing water

  5. burning a candle

Show answer
Correct Option: E
Explanation:

Burning of candle is a chemical change because the wax gets converted into carbon dioxide whereas the rest of the options represent the physical change.


Hence the correct option is E.

Insoluble impurities from solution during crystallization are removed by :

chemistry changes around us crystallisation process of separating components of a mixture physical changes

  1. drying

  2. filtration

  3. heating

  4. cooling

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Correct Option: B
Explanation:

Heating is the process of increasing the temperature of a body from its original temperature.

Cooling is the process of decreasing the temperature of a body from its original temperature.
Filtration is the process of separating small particles of solid matter from a liquid, by causing the liquid to pass through the pores of some substance, called a filter.
Insoluble impurities from solution during crystallization are removed by filtration as the insoluble solid particles passed through the filter.
Drying is the process of drying up the liquid present on any material by heating the material.
Option B is correct.

While forming crystals, it is important to :

chemistry changes around us crystallisation process of separating components of a mixture physical changes

  1. evaporate to dryness to get purest possible crystals

  2. attach gas syringes to collect fumes

  3. not evaporate water of crystallization

  4. use high flames

Show answer
Correct Option: C
Explanation:

Crystals contain water of crystallization hence during formation of crystals water of crystallization should not be evaporated.

Also, crystallization is the process of formation of crystals. Crystals is defined as the highly organized molecule into a well-known structure.

Crystallisation is an example of chemical change.

chemistry changes around us crystallisation process of separating components of a mixture physical changes

  1. True

  2. False

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Correct Option: B
Explanation:

Crystallization is a process of formation of solid crystals in a homogenous solution. Thus it is a physical process and not a chemical process.

The forbidden gap in germanium crystal is

chemistry changes around us crystallisation process of separating components of a mixture physical changes

  1. 0.7 eV

  2. $1.12X10^{19} J$

  3. Both 1 and 2

  4. $1.1eV$

Show answer
Correct Option: A
Explanation:

The energy difference between the valance and conduction band is called Forbidden energy gap$.$

The forbidden gap in germanium crystal is $0.7 eV$
Hence$,$ o[ption $(A)$ is correct$.$

Which of the following is not a feature of chemical change?


(I) Original substance can be obtained by simple physical methods.
(II) It is a temporary change.
(III) The new substances formed have properties different from those of the reacting substances.

chemistry changes around us crystallisation process of separating components of a mixture physical changes

  1. I, II

  2. I, III

  3. II, III

  4. All of the above

Show answer
Correct Option: A
Explanation:

One more new substances one formed in a chemical change. The new substances formed have properties different from those of the reacting substances. A chemical change is always accompanied by the absorption or evolution of energy in the form of heat, light or sound.

Sun tanning is a/an :

chemistry changes around us crystallisation process of separating components of a mixture physical changes

  1. physical change

  2. chemical change

  3. both a and b

  4. intermediate

Show answer
Correct Option: B
Explanation:

Sun tanning is a chemical change as vitamin D and melanin are produced during tanning. As new products are formed during sun tanning, it is considered to be a chemical change.