As promised, here are the answers for the questions posed. Remember to revise through your past year topics each week. One topic/question a week will go a long way to help you for your final revision for PSLE. Lets' work hard together!
Answer for (a)
She would observe the drop of blue ink rising up the glass tube.
Explanation: Most matter expand when heated. When heat is supplied to the flask, it gains heat. The air in the flask also gets heated. This air expands, increases in volume and moves up the glass tube, pushing the drop of ink up the glass tube.
Answer for (b)
The drop of ink would move down the glass tube.
Explanation: When the flask is placed in ice water, the flask and air cool down, contract and decrease in volume. The drop of blue ink oves down the glass tube.
Answer for (c)
It shows hot air expands when heated and contracts when cooled.
Explanation: The concept here is showing expansion and contraction when heated and cooled respectively. The matter involved is air.
Answer:
1. Good conductors of heat:
Aluminium, Copper, Silver
2. Poor conductors of heat:
Wool, Sawdust, Cotton
Alternative answer:
1. Metals:
Aluminium, Copper, Silver
2. Non-metals:
Wool, Sawdust, Cotton
Sincerely,
Mr Nelson Ong
it usually falls before it rises dose nt it?
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