Tag: changes and its classification

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

Which of the following is true?

  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.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

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

Which of the following is true?

  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.
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

Choose the incorrect statement(s).

  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.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Physical changes are generally reversible (e.g., melting ice), whereas chemical changes are generally irreversible. Therefore, the statement that physical changes are not reversible is incorrect.

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

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

  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
Reveal answer Fill a bubble to check yourself
B,C Correct answer
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.
Multiple choice chemistry phenomena around us changes and its classification types of changes classification of changes

Cooking of rice is an example of:

  1. irreversible change

  2. endothermic reaction
  3. both $A$ & $B$

  4. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

The growth of seedlings in a crop is a:

  1. undesirable change

  2. desirable change

  3. reversible change

  4. physical change
Reveal answer Fill a bubble to check yourself
B Correct answer
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...

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

A seed growing into a tree is an example of:

  1. slow physical change

  2. fast periodic change

  3. slow natural change

  4. man-made reversible change
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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?

  1. Irreversible changes

  2. Chemical changes

  3. Periodic changes

  4. Undesired changes
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.