Tag: physical changes

Questions Related to physical changes

Maximum conductivity would be of : 

chemistry changes - physical and chemical physical changes changes and their classification physical changes

  1. $K _{3}Fe(CN) _{6}[0.1 M Solution]$

  2. $K _{3}Ni(CN) _{6}[0.1 M Solution]$

  3. $FeSO _{4}.Al _{2}(SO _{4}) _{3}.24H _{2}O[0.1 M Solution]$

  4. $Na _{3}[Ag(S _{2}O _{3}) _{2}][0.1 M Solution]$

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Correct Option: C

Which of them is not the characteristics of a physical change?

chemistry change around us physical changes changes and their classification physical changes

  1. Change in the physical properties

  2. New substances are formed

  3. Reversible reaction

  4. Original substance can be riveted back

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Correct Option: B
Explanation:

1) A physical change is temporary and is usually reversible.
2) No new substances are formed during a physical change.
3) There is no change in mass of the substance during a physical change.
4) There is no net absorption or release of energy during a physical change.

The process in which the state of a substance changes from solid to liquid is called:

chemistry change around us physical changes changes and their classification physical changes

  1. boiling

  2. condensation

  3. freezing

  4. melting

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Correct Option: D
Explanation:

When a solid is heated, the particles are given more energy and start to vibrate faster. At a certain temperature, the particles vibrate so much that their ordered structure breaks down. At this point the solid melts into liquid. This temperature change from solid to liquid is called  the melting point. Each solid has a set melting point at normal air pressure, but at higher altitudes the melting point lowers.

On decreasing temperature, a liquid turns into solid. This is:

chemistry change around us physical changes changes and their classification physical changes

  1. condensation

  2. melting

  3. freezing

  4. sublimation

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Correct Option: C
Explanation:

On decreasing temperature, a liquid turns in to solid, this process is called Freezing. Freezing or solidification is a phase transition state.
Most liquids freeze by crystallization. formation of crystalline solid from the uniform liquid. this is a first-order thermodynamic phase transition i.e as long as solid and liquid coexist the temperature of the whole system remains very nearly equal to the melting point due to slow removal of heat when in contact with the air, which is a poor heat conductor.

When a solid directly turns into gaseous state, it is called:

chemistry change around us physical changes changes and their classification physical changes

  1. sublimation

  2. condensation

  3. polymerisation

  4. melting

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Correct Option: A
Explanation:

Sublimation is the transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase. Sublimation is an endothermic phase transition that occurs at temperatures and pressures below a substance's triple point in its phase diagram. The reverse process of sublimation is desublimation or deposition.

Properties like shape, magnetic properties etc. are changed in:

chemistry change around us physical changes changes and their classification physical changes

  1. chemical change

  2. physical change

  3. Both A and B

  4. None of the above

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Correct Option: B
Explanation:

During a physical change, physical properties such as colour, volume, size, shape and magnetic properties etc. of the substances may change.

Dissolution of common salt or sugar in water is an example of:

chemistry change around us physical changes changes and their classification physical changes

  1. physical change

  2. chemical change

  3. both A and B

  4. none of the above

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Correct Option: A
Explanation:

A change in which only the physical properties of the substance get changed, when the chemical composition remain unchanged is called a physical change. Here we can obtain the sugar by boiling water.

Example of the physical change is :
chemistry change around us physical changes changes and their classification physical changes

  1. respiration (inhaling oxygen gas and exhaling carbon dioxide gas)

  2. mixing vinegar and baking soda

  3. evaporating water

  4. burning fuel in your car

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Correct Option: C
Explanation:

In evaporation of water, only the physical state of water changes from liquid to gas, but not the chemical composition of water.

Hence the correct answer is option C.

When salt is dissolved in a glass of water, how many new substances are formed?

chemistry change around us physical changes changes and their classification physical changes

  1. $1$

  2. $2$

  3. $3$

  4. None

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Correct Option: B

Which of the following is a physical change?

chemistry change around us physical changes changes and their classification physical changes

  1. Magnetisation of iron

  2. Curdling of milk

  3. Burning of a candle

  4. Cooking of food

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Correct Option: A
Explanation:

Magnetization of iron is a physical change and not a chemical change as there is no change of state, no change of temperature, no smell and no evolution of gas. It is because: - No Chemical process is involved. - After demagnetizing the iron it will lose its magnetic power.