Assertion and Reason


Direction: Choose the correct alternative from the following options as given below for the Assertion (A) and Reason (R) given in each of the questions.

  1. Assertion (A)
    Alcohol rather than mercury is used in a thermometer to measure a temperature of - 60 C.
    Reason (R)
    Alcohol has a lower freezing point than mercury.









  1. View Hint View Answer Discuss in Forum

    We know that, mercury freezes at -39 C, while alcohol freezes at a point far below - 100 C. So, alcohol is used to measure lower temperatures. Similarly, mercury boils at 357 C, while alcohol boils at 78 C. So, mercury is used to measure high temperature.

    Correct Option: A

    We know that, mercury freezes at -39 C, while alcohol freezes at a point far below - 100 C. So, alcohol is used to measure lower temperatures. Similarly, mercury boils at 357 C, while alcohol boils at 78 C. So, mercury is used to measure high temperature.


  1. Assertion (A)
    Tides indicate the regular and periodic rise and fall in sea level.
    Reason (R)
    Tides are caused by the gravitational pull of the Moon and sea level.









  1. View Hint View Answer Discuss in Forum

    Both the assertion and reason are true but reason are true but reason is not the correct explanation of assertion.

    Correct Option: B

    Both the assertion and reason are true but reason are true but reason is not the correct explanation of assertion.



  1. Assertion (A)
    Graphite is slippery and used as a lubricant.
    Reason (R)
    Graphite has free electrons.









  1. View Hint View Answer Discuss in Forum

    In graphite, each carbon atoms is linked to three other carbon atoms, while one electron in the carbon atom is delocalised. So, graphite has free electrons and it is also used as a lubricant but reason does not explains assertion.

    Correct Option: B

    In graphite, each carbon atoms is linked to three other carbon atoms, while one electron in the carbon atom is delocalised. So, graphite has free electrons and it is also used as a lubricant but reason does not explains assertion.


  1. Assertion (A)
    When common salt is kept open, it absorbs moisture from the air.
    Reason (R)
    Common salt contains magnesium chloride.









  1. View Hint View Answer Discuss in Forum

    We know that, common salt contains magnesium chloride. Therefore, it absorbs moisture from the air.

    Correct Option: A

    We know that, common salt contains magnesium chloride. Therefore, it absorbs moisture from the air.



  1. Assertion (A)
    The steam engine was invented by James Watt.
    Reason (R)
    There was a problem of taking out water from flooded mines.









  1. View Hint View Answer Discuss in Forum

    Assertion is correct but reason is false.

    Correct Option: C

    Assertion is correct but reason is false.