Chemistry
Assertion (A): Conversion of a substance in solid state to its liquid state is called melting.
Reason (R): On heating, the kinetic energy of solid molecules increases.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
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Answer
Both A and R are true but R is not the correct explanation of A.
Explanation — A is true as the process by which a substance changes from solid to liquid is called melting or fusion.
R is true as on heating, the kinetic energy of solid molecules increases. However, this statement only gives the effect of heating and does not fully explain melting as the change of a solid into a liquid at its melting point by overcoming intermolecular forces of attraction.
Therefore, Both A and R are true but R is not the correct explanation of A is the correct option.
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Fill in the blanks:
(a) The change of a solid into a liquid is called …………… .
(b) The process in which a solid directly changes into gas is called …………… .
(c) The change of water vapour into water is called …………… .
(d) The temperature at which a liquid starts changing into its vapour state is …………… .
(e) A gas can be changed into a liquid and then into solid by ............... its pressure and cooling .
(f) LPG cylinders contain cooking gas in ............... state at high pressure.
(g) In a chemical reaction, the total mass of the reactants is ............... to the total mass of the products.