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Comment on the following statements. (...

Comment on the following statements.
(a) Evaporation produces cooling.
(b) Rate of evaporation of an aqueous solution decreases with increase in humidity .
(c) Sponge though compressible is a solid.

Text Solution

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(a) Evaporation produces cooling. This is based on the fact that when a liquid evaporates, it takes (or draws) the latent heat of vaporisation from 'another matter' which it touches. This 'another matter' looses heat and gets cooled. Therefore, evaporation causes cooling.
(b) If humidity is high, then air is already saturated with water vapour, i.e., it has a lot of water vapours. Therefore, it will not take more water vapours easily. Hence, rate of evaporation decreases.
(c) Sponge has minutes holes in which air is trapped. The material is also so rigid. On pressing this, air is expelled out, that is why it can be compressed but is solid as it has a definite shape and volume and does not change its shape unless compressed.
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Knowledge Check

  • Speed of sound waves in air a) is independent of temperature b) increases with pressure c) increases with increase in humidity d) decreases with increase in humidity.

    A
    is independent of temperature
    B
    increases with pressure
    C
    increases with increase in humidity
    D
    decreases with increase in humidity.

  • Rank the following reaction A, B and C in order of increasing rate,

    A
    `B gt A gt C`
    B
    `B gt C gt A`
    C
    `A gt B gt C`
    D
    `A gt C gt B`

  • Which of the following statement is correct? A)The rate of a reaction decreases with passage of time as the concentration of reactants decreases. B)The rate of a reaction is same at any time during the reaction C)The rate of a reaction is independent of temperature change D)The rate of a reaction decreases with increase in concentration of reactant(s)

    A
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    B
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