Tag: changes and its classification

Questions Related to changes and its classification

Change of water into vapor (Vaporization) is which of the following change

chemistry phenomena around us changes and its classification types of changes classification of changes

  1. Physical and reversible change.

  2. Chemical and reversible change.

  3. Physical and irreversible change.

  4. Irreversible change

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Correct Option: A
Explanation:

Vapor is another physical state of water. Water can be obtained from the  condensation of vapor. This is a physical and reversible change.

Burning of Magnesium ribbon is a _______

chemistry phenomena around us changes and its classification types of changes classification of changes

  1. Chemical change

  2. Physical change

  3. Reversible change

  4. None of the above

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Correct Option: A
Explanation:

Magnesium ribbon burns with dazzling light in air and forms magnesium oxide.
$2Mg+O _2\rightarrow 2MgO$.
The above change is a chemical changes as new substance is  formed after change. Original
substances cannot be retrieved by simple physical processes.So it is chemical change.
Hence option A is correct.

Things or processes which can be reversed are called

chemistry phenomena around us changes and its classification types of changes classification of changes

  1. Reversible process

  2. Irreversible process

  3. Cyclic process

  4. None of the above

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Correct Option: A
Explanation:

Things or processes which can be reversed are called reversible. For example, ice melts into water and water freeze into ice which is reversible. Hence, option A is correct.

Calcium carbide produces acetylene on reaction with water. Ethylene can be obtained by reduction of ${C} _{2}{H} _{2}$. Polythene is produced by polymerization of ${C} _{2}{H} _{4}$. Calculate the theoretical yield of polythene per kilogram of $Ca{C} _{2}$ :

chemistry phenomena around us changes and its classification types of changes classification of changes

  1. $0.6457kg$

  2. $0.4375kg$

  3. $0.5113kg$

  4. $0.3948kg$

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Correct Option: B

Examples of slow reaction are:

chemistry phenomena around us changes and its classification types of changes classification of changes

  1. rusting of iron

  2. weathering of rocks

  3. neutralization of sodium hydroxide by hydrochloric acid

  4. formation of coal

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Correct Option: A,B,D
Explanation:
Reactions that take a while are slow reactions and those which occur within a few seconds are fast reactions. The rusting of iron, the fermentation of sugar into alcohol, the chemical weathering of rocks (breaking down of rocks), the photosynthesis process in plants, coal formation are slow reactions. Whereas neutralization reaction of a strong base like sodium hydroxide and strong acid like $HCl$ is a fast reaction.
option A,B,D are correct

Which of the following is a chemical change

chemistry phenomena around us changes and its classification types of changes classification of changes

  1. Burning of coal

  2. Dissolving sugar in water

  3. Dissolving salt in water

  4. Melting of ice

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Correct Option: A
Explanation:

A chemical change is the process in which chemical composition of the substance is changed,and physical composition may or may not changed burning of coal that is carbon(C) in presence of oxygen gives a different chemical substance $CO _2$. So, it is a chemical change. Hence option A is correct.

Melting of wax is

chemistry phenomena around us changes and its classification types of changes classification of changes

  1. Reversible change

  2. Irreversible change

  3. Both A,B

  4. None of the above

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Correct Option: A
Explanation:

In melting of wax, only the physical state of the wax changes from solid to liquid. Solid wax can be obtained from molten wax. Molten wax can be again converted to solid wax. This is an example of physical and reversible change. Hence, option A is correct.