Q&A - PSLE Science

[htn]

Leon Wee Onn Leon:

htn:

need help, Rosyth preliminary 2010


Q22. A block of ice is put in a sealed plastic box.The box is then placed in the middle of a classroomon a hot day.

What will happen to the temperature of the melting ice, the water and the air in the box after some time?


Temperature of

melting ice water air in the box

1.remains the same increases decreases
2.decreases remains the same increases
3.remains the same decreases decreases
4.increases remains the same increases

what is the ans?

TIA

I think the answer should be (1).

When an ice cube melts, it's temperature will still remain at 0 Degrees Celsius, only when the ice melts completely, the water from it will increase in temperature. The warm air in the container loses heat to the ice cube, thus making the air to drop in temperature. As a result, the ice gained heat and will melt.

Leon Wee Onn Leon

Thanks

[Nebbermind]

For the melting ice problem, shdn’t it be :


remain, remain & decrease? (since it stated ‘melting ice’, so water must be ‘0’)

[Angrybirdlover]

P5G:

Please help.
[quote]

http://i56.tinypic.com/x5s28l.gif\">


TIA.[/quote]Bubbles will soon appear :imdrowning:

[Angrybirdlover]

Nebbermind:

For the melting ice problem, shdn't it be :


remain, remain & decrease? (since it stated 'melting ice', so water must be '0')

Ice will remain the same since it is melting at 0 degrees. Water will gain temperature since it's not melting :imcool:

[Angrybirdlover]

P5G:

Please help.


http://i56.tinypic.com/x5s28l.gif\">


TIA.

Then the leaf will absorb water if it does not photosynthesise it will not be able to get rid of the water. The green parts will photosynthesise so water will not enter, causing leaf to be lighter and float. :?

[andante]

Newkiasu2011:

Does anyone have answers to booklet A for nan hua science prelims 2011? Pls help, if you do. TIA

Hi,
Does anyone know where to download Nanhua prelims 2011 science paper ?

Thx

[Guitar]

Verysuperkiasu:

Anyone can share about the swasthikaa answer keys for section A prelim 2011? My son didn't agree with quite a few of them. Hope someone could verify...


Unfortunately I don't have a scanner. One of them is as follows

Which of the following statements about the organism below are correct? Picture shows a frog.

A. It has many cells of various shapes and sizes.
B. It has cells which contain nuclei that pass hereditary materials down.
C. It has different cells to carry out different functions.
D. Cell division takes place as it grows.
E. It has some cells that are surrounded by cellulose walls.

(1) A, B and C only
(2) A, B and D only
(3) A, B, C and D only
(4) A, C, D and E only

Son's answer is (3) but answer key is (2). Which is correct?

Qn 12 : Stephanie counted the no of plants & animals in her garden. Her findings are shown in the graph below.

No. of plants that grow on the ground = 10
No. of plants that grow on trees = 7
No of grasshoppers = 5
No of Lime Butterflies = 6
No of caterpillars of lime butterflies = 8

Based on the graph above (supposed to be a graph), which of the following statemets are definitely true?

A: There are at least 3 populations of animals
B: There are more plants than animals in Stephanie's garden.
There are at least 2 populations of plants.
There is only one garden community

(1) A only
(2) B and C only
(3) C and D only
(4) A, C and D only

Son's answer is (3) but answer key is (4)

For q12 my DD asked her science teacher. He said that 3 is the correct ans. The young of the lime butterfly is not considered a different population.

[atutor2001]

P5G:

Please help.


http://i52.tinypic.com/i3gzux.gif\">

TIA.

(a) When the nuclei are removed, the cells will die because the nucleus control all the activities in a cell.

(b) Our skin will wrinkle after soaking in water because the cell membrane of our skin allows water to pass through causing it to expand. However, the expansion is not even causing our skin to wrinkle. (This is definitely out of syllabus)

[atutor2001]

P5G:

Please help.


http://i56.tinypic.com/x5s28l.gif\">


TIA.

(a) Bubbles can be seen on the surface of the green discs but there will be no bubble on surface of the white discs.

(b) The green discs contain chlorophyll and can carry out photosynthesis, releasing oxygen which appears as bubbles. Bubbles on the surfaces of the green discs help the green discs to float to the surface. The white discs do not contain chlorophyll and cannot photosynthesize.

[atutor2001]

P5G:

Please help.


http://i56.tinypic.com/34isp44.gif\">


TIA.

(a) Part A will grow new shoots while part B will wither and die.

(b) Part A has roots to absorb water and nutrient from the ground. It also has food stored in its stems and roots. Therefore, it can grow new shoots.

Part B has leaves which allow water vapour from part B to be released through the stomata. However, it does not have roots to absorb water. With water being lost continuously through the leaves, part B will wither and die.