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10 questions
The process of converting solid directly into gas is known as _________________________
Condensation
Sublimation
Melting
Evaporation
Which of the following is a reversible change ?
Burning of forests
Ripening of fruits
Burning of candle
Melting of ice
Iron rim is made slightly smaller than the wooden wheel. The rim is usually heated before fixing into the wooden wheel, because on heating the iron rim -
Expands and fits onto the wooden wheel.
Contracts and fits onto the wooden wheel.
No change in the size takes place.
Expands first, then on cooling contracts and fits onto the wooden wheel.
Salt can be separated from its solution (salt dissolved in water), because -
Mixing of salt in water is a change that can be reversed by heating and melting of salt.
Mixing of salt in water is a change that cannot be reversed.
Mixing of salt in water is a permanent change.
Mixing of salt in water is a change that can be reversed by evaporation.
Melting is a process when -
Water changes into ice
Ice changes into water
Water changes into vapours
Ice changes into vapours
State whether yes or no.- Can the change in the length of the candle that occurred during burning, be reversed ?
Yes
No
Changes can occur by their own also .
Yes, in every case
Never
True
False
Changes may occur -
Only by mixing a substance with some other substance
Only by heating a substance
Both by heating a substance and by mixing it with some other
None of these options is correct
The following change can not be reversed -
Paper aeroplane to a paper
Fully blown balloon to the balloon
Baked roti to the ball of dough
Rolled out roti to a ball of dough
On continuously heating water into a pan -
The quantity of water in the pan decreases
The quantity of water in the pan increases
The quantity of water in the pan remains constant
Can’t say anything in this case
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