Tag: classification of changes

Questions Related to classification of changes

Which of the following is true?

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

  1. Melting of ice is reversible change.

  2. Burning of magnesium is reversible change.

  3. Rusting of iron is reversible change.

  4. All of the above.

Show answer
Correct Option: A
Explanation:

The statement (A) is true.
Melting of ice is reversible change.
Burning of magnesium is irreversible change.
Rusting of iron is irreversible change.

Which of the following is true?

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

  1. A physical change can never be reversible.

  2. A chemical change can never be reversible.

  3. Both of the above

  4. A physical change may be reversible.
    Also, a chemical change may be reversible.

Show answer
Correct Option: D
Explanation:

A physical change may be reversible. For example, melting of ice is a reversible change.
Also, a chemical change may be reversible. For example, the reaction between $\displaystyle N _2$ and $\displaystyle H _2$ to form $\displaystyle NH _3$ is a reversible chemical change.

Choose the incorrect statement(s).

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

  1. Chemical reactions are characterized by the change in colour.

  2. Chemical reactions are not alone characterized by change in state.

  3. Physical changes are characterized by the change in colour of reacting substances.

  4. Physical changes are not reversible.

Show answer
Correct Option: D

When sugar is stirred with a spoon in a glass of water, more sugar is dissolved and faster. Why?

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

  1. Spoon acts as a catalyst

  2. On stirring, temperature increases

  3. Stirring increases the rate of interaction

  4. Spoon increases the attraction between the molecules of water and sugar

Show answer
Correct Option: B,C
Explanation:
Stirring, or agitation helps to disperse the particles of sugar throughout the water, which is another way of increasing the surface area of the sugar and accelerating the time it takes to dissolve. The stirring motion also increases kinetic energy, which increases the temperature of the solution – and that's the next way to make sugar dissolve more quickly. An increase in the kinetic energy of the constituent particle increases the rate of interaction as well as the temperature of the solution.

Hence, option (B) & (C)  are correct.

Cooking of rice is an example of:

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

  1. irreversible change

  2. endothermic reaction

  3. both $A$ & $B$

  4. none of the above

Show answer
Correct Option: C
Explanation:

Cooking of rice is both irreversible and endothermic reaction. i.e once cooked rice cannot be made rice back and the rice absorbs heat from the external sources and utilizes for its cooking so it is endothermic.

The growth of seedlings in a crop is a:

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

  1. undesirable change

  2. desirable change

  3. reversible change

  4. physical change

Show answer
Correct Option: B
Explanation:

The growth of seedlings in a crop is a desirable change i.e the changes which are beneficial to nature or which does not cause any harm to nature.

Few of the examples are curdling of milk, seed germination etc...

A seed growing into a tree is an example of:

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

  1. slow physical change

  2. fast periodic change

  3. slow natural change

  4. man-made reversible change

Show answer
Correct Option: C
Explanation:

A seed growing into a tree is an example of a slow and natural process. Slow because it takes days to sometimes months for a seed to develop into a sapling and then years to a develop into a tree. All these processes occur naturally using all natural resources like water, sunlight, soil.

What's common among motion of the planets around the sun, blinking of traffic lights and motion of blades of a fan rotating at uniform speed?

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

  1. Irreversible changes

  2. Chemical changes

  3. Periodic changes

  4. Undesired changes

Show answer
Correct Option: C
Explanation:

The planets around the sun, blinking of traffic lights and motion of blades of a fan rotating at uniform speed are all periodic changes.
Changes which are repeated after regular intervals are called periodic changes.

If two substances interact to produce a change, they will do so:

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

  1. under any condition

  2. no matter what kind of interaction there is

  3. only if the interaction is of the right kind and under the right conditions

  4. only if they are in close contact with each other

Show answer
Correct Option: C
Explanation:

According to transition state theory, two molecules interact with each other when they are aligned in a proper orientation.

Hence, two substance interact to produce a change only if the interaction is of the right kind under right conditions.

Halley's comet revolves around the sun once in every 76 Years. This is a:

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

  1. photochemical change

  2. periodic change

  3. chemical change

  4. irreversible change

Show answer
Correct Option: B
Explanation:

It is a periodic change $-$ because changes that occur after a fix interval of time is known as periodic change.

Here periodic change in $76$ years
photochemical change is due to light chemical change $-$ where reactant react to produce products.