Tag: classification of changes

Questions Related to classification of changes

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

Show answer
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

Show answer
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. $0.3948kg$

Show answer
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

Show answer
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

Show answer
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

Show answer
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.

 Heat gain makes ice to:

chemistry changes around us can all changes be reversed? substances and objects classification of changes

  1. freeze

  2. evaporate

  3. melt

  4. dissolve

Show answer
Correct Option: C
Explanation:

When heat flows through the ice, the ice will melt. 

The liquid has more energy than the solid, mainly because the molecular bonds in the solid adjust to low-energy positions. So energy, when flowed in, will convert the solid to the liquid.
Freezing will happen if the there is heat loss to ice.
Evaporation will happen if the heat gain is very high that makes the ice to convert to water vapor.
The correct answer is option $ C$.

Which of the following is/are different ways to bring a change?

chemistry changes around us can all changes be reversed? substances and objects classification of changes

  1. Expansion

  2. Contraction

  3. Evaporation

  4. All of the above.

Show answer
Correct Option: D
Explanation:

All of the following is/are different ways to bring a change.
Expansion, Contraction, Evaporation,Melting.

What are the different conditions for a chemical reaction to take place?

chemistry changes around us can all changes be reversed? substances and objects classification of changes

  1. Heating

  2. Mixing

  3. Boiling

  4. All of the above

Show answer
Correct Option: D
Explanation:

D, Temperature and close contact plays important roles in chemical reactions. These factors affects the activation energy of the reaction.

In the tools which are used to dig the soil, the iron blade in these tools fixed to the wooden handle. Which of the following is used during the change?

chemistry changes around us can all changes be reversed? substances and objects classification of changes

  1. Expansion

  2. Contraction

  3. Both expansion and contraction.

  4. Neither expansion and contraction.

Show answer
Correct Option: C
Explanation:

Both expansion and contraction is used during the change.
The iron blade has a ring in which the wooden handle is fixed. The ring is slightly smaller in size than the wooden handle.The ring is heated and it becomes slightly larger in size (expands). The handle  fits into the ring. When the ring cools it contracts and tightly fits on the handle.