Mrs Singh placed materials J, K, L and M in between two steel cups and poured water at 95 oC into each of the steel cups as shown below. She covered each inner cup with a plastic lid and measured the temperature of the water after 20 minutes. The temperatures of water recorded at the end of the experiment are shown below.
Which material would be able to allow ice to melt at the slowest rate?
(1) Material J
(2) Material K
(3) Material L
(4) Material M ( )
2) 4 identical beakers of tap water were heated using different number of burners of the same type. Beakers A and B was each filled with 50 ml of water while beakers C and D was each filled with 150 ml of water.
50ml 50ml 150ml 150ml
Which of the following shows the correct order of time taken for each beaker of water to boil, beginning from the shortest to the longest time?
(1) A, B, C, D
(2) A, B, D, C
(3) C, D, B, A
(4) D, A, B, C ( )
3) Rashid poured an equal amount of water at 100 oC into three containers of the same size and equal thickness. The three containers were made of different materials.
The table below shows the time taken for the temperature of water to reach room temperature.
Container
|
P
|
Q
|
R
|
Time taken to reach room temperature (min)
|
20
|
60
|
45
|
4) Peter carried out an experiment to learn more about the transfer of heat.
He placed a piece of ice on End A of a metal plate as shown in the diagram below.
(a) After 10 minutes, End B of the metal plate felt cold. Explain clearly why. [2m]
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Next, Peter took out two similar ice-cubes from the freezer and put them on two similar plates. He crushed one of the ice-cubes. Then, using a stopwatch, he measured the time taken for the ice on each plate to melt completely into water.
(b) Which will melt faster, the ice cube or the crushed ice? Give a reason for your answer. [2m]
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Answer Key
Qn
|
Answer
|
(1)
|
1
|
(2)
|
2
|
3a) 30oC (1m)
b) Graph should start from 100oC and end at 30oC at 20 minute. (1m)
c) Container P. The temperature of water in Container P dropped at the fastest rate/ takes the shortest time to reach room temperature. (1m)
4a) The heat travelled / is transferred from End B to End A through the metal plate, causing heat loss at End B. (2m)
b) Crushed ice. It has the greater exposed surface area. (1m)
