Allied solutions

Allied solutions

Grade 7

Physical and Chemical Changes | Exercise

Question 1

Q1) Change is the law of nature and occurs in our everyday life, at all times and in all places.

Differentiate between the following changes with a suitable example.

  1. Desirable and undesirable change
  2. Periodic and non-periodic change
  3. Slow and fast change
  4. Natural and man-made change
  5. Reversible and irreversible change.

Solution:

  1. Desirable and undesirable change
    Desirable Change Undesirable change
    Changes that take place naturally or artificially and produce useful and required results are desirable changes. Changes that take place naturally or artificially and produce not useful or bad results are undesirable changes.
    Example - - Rainfall on crops - Conversion of milk to curd - Growth of seedling into plants. Example - - Rotting of fruits - Falling of trees - Excessive rainfall causing floods
  2. Periodic and non-periodic change
    Periodic Change Non-periodic change
    Changes that take place at regular intervals of time are periodic changes. Changes which take place irregularly and do not repeat are non-periodic changes.
    Example - - Change of seasons - Movement of clock hands - Day turning into night Example - - Rusting of iron - Change in weather - Thunder and lightning
  3. Slow and fast change
    Slow Changes Fast Changes
    Changes that take place gradually over time, days, months or even years are slow changes. Changes that take place quickly in seconds or minutes are fast changes.
    Example - - Growing of trees - Tooth decay - Decomposition of soil Example - - Burning of paper - Bursting of fireworks - Lighting of bulb
  4. Natural and Man-made changes
    Natural Changes Man-made Changes
    Changes that take place naturally and not artificially are natural changes. Changes that do not take place naturally but are artificial and man-made are man-made changes.
    Example - - Growth of the Human Body - Change in seasons Example - - Conversion of metals into alloys - Burning of fuel - Cutting of trees
  5. Reversible and irreversible change.
    Reversible Changes Irreversible Changes
    Changes which are not permanent and can be reversed by another change are reversible changes. Changes which are permanent and cannot be reversed by any change.
    Example - - Melting of wax - Melting of ice - Pulling of rubber band Example - - Burning of paper - Rusting of iron - Curdling of milk

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subject-cta

Question 1

Q1) Change is the law of nature and occurs in our everyday life, at all times and in all places.

Differentiate between the following changes with a suitable example.

  1. Desirable and undesirable change
  2. Periodic and non-periodic change
  3. Slow and fast change
  4. Natural and man-made change
  5. Reversible and irreversible change.

Solution:

  1. Desirable and undesirable change
    Desirable Change Undesirable change
    Changes that take place naturally or artificially and produce useful and required results are desirable changes. Changes that take place naturally or artificially and produce not useful or bad results are undesirable changes.
    Example - - Rainfall on crops - Conversion of milk to curd - Growth of seedling into plants. Example - - Rotting of fruits - Falling of trees - Excessive rainfall causing floods
  2. Periodic and non-periodic change
    Periodic Change Non-periodic change
    Changes that take place at regular intervals of time are periodic changes. Changes which take place irregularly and do not repeat are non-periodic changes.
    Example - - Change of seasons - Movement of clock hands - Day turning into night Example - - Rusting of iron - Change in weather - Thunder and lightning
  3. Slow and fast change
    Slow Changes Fast Changes
    Changes that take place gradually over time, days, months or even years are slow changes. Changes that take place quickly in seconds or minutes are fast changes.
    Example - - Growing of trees - Tooth decay - Decomposition of soil Example - - Burning of paper - Bursting of fireworks - Lighting of bulb
  4. Natural and Man-made changes
    Natural Changes Man-made Changes
    Changes that take place naturally and not artificially are natural changes. Changes that do not take place naturally but are artificial and man-made are man-made changes.
    Example - - Growth of the Human Body - Change in seasons Example - - Conversion of metals into alloys - Burning of fuel - Cutting of trees
  5. Reversible and irreversible change.
    Reversible Changes Irreversible Changes
    Changes which are not permanent and can be reversed by another change are reversible changes. Changes which are permanent and cannot be reversed by any change.
    Example - - Melting of wax - Melting of ice - Pulling of rubber band Example - - Burning of paper - Rusting of iron - Curdling of milk

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subject-cta
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