Physics
Assertion (A) : Glass containers with narrow necks are more likely to break when hot water is poured into them suddenly.
Reason (R) : Glass is a good conductor of heat.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Heat Energy
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Answer
Assertion is true but reason is false
Explanation
Assertion (A) is true because when hot liquid is poured into a glass container, the inner surface of the glass becomes hot, while its outer surface remains at the room temperature. Therefore, the inner surface of the container expands, while its outer surface does not expand so this unequal expansion cracks and ultimately breaks the glass container.
Reason (R) is false because glass is a poor conductor of heat.
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Related Questions
The correct statement is:
- Iron rims are cooled before they are placed on the cart wheels.
- A glass stopper gets tightened on warming the neck of the bottle.
- Telephone wires sag in winter, but become tight in summer.
- A little space is left between two rails on a railway track.
Assertion (A) : A humid environment slows the rate of evaporation.
Reason (R) : In humid environment, vapour molecules do not find the space to escape.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Assertion (A) : A gas expands less than a liquid for the same rise in temperature.
Reason (R) : Gases have negligible intermolecular forces of attraction.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Fill in the blanks:
(a) Boiling occurs at …………… .
(b) Evaporation takes place at …………… .
(c) The molecules of liquid …………… heat from surroundings in evaporation.
(d) Heat is …………… during boiling.
(e) Cooling is produced in …………… .
(f) A longer rod expands …………… than a shorter rod on being heated to the same temperature.
(g) Liquids expand …………… than the solids.
(h) Gases expand …………… than the liquids.
(i) Alcohol expands …………… than water.
(j) Iron expands …………… than copper.