Q&A - PSLE Science

[tianzhu]

Hi Drdj


Could you help to provide the sources of your questions eg ACS P6 Sci Q35 SA2 2008?

It appears to me that the questions are from different levels? Just curious, are you a parent or student?

The scanned image may be slightly blurred and small and it may helpful to refer to the originals from http://www.wendykoh.com. Otherwise, it's very taxing for an old man like me to read.

[Dharma]

Drdj:

Dear tianzhu and dharma,


Thanks so much !! Appreciate your detailed explanations !!
Have scanned some further queries from various sources - hope you can help me with them - apologies for the many attachments, as I'm not sure how to do it all in 1 !!
Thanks again

http://www.postimage.org/image.php?v=PqmEELA

Dear Drdj,

Q4) Volume of air will be 500cm3 and 300cm3 in Flask A and B respectively.
Air does not have a definate volume and will spread to occupy the whole container it is in. The capacity of Flask A is 500cm3, so no matter how much air is pumped in, air will compress to occupy the capacity of the flask.

As for flask B, there is 200cm3 of water in it which cannot be compressed. So, air can only occupy the balance 300cm3 space in the flask.

[Dharma]

Drdj:

Dear tianzhu and dharma,


Thanks so much !! Appreciate your detailed explanations !!
Have scanned some further queries from various sources - hope you can help me with them - apologies for the many attachments, as I'm not sure how to do it all in 1 !!
Thanks again

http://www.postimage.org/image.php?v=PqmEHfJ

Air will compress to occupy the max. space in the jar (200cm3)

[Dharma]

Drdj:

Dear tianzhu and dharma,


Thanks so much !! Appreciate your detailed explanations !!
Have scanned some further queries from various sources - hope you can help me with them - apologies for the many attachments, as I'm not sure how to do it all in 1 !!
Thanks again

http://www.postimage.org/image.php?v=PqmEJKS

Q46
a) To find out how different temperatures of water in which the test tube containing yeast with sugar solution is immersed affect the amount of CO2 produced by the yeast.

b) 60 degrees celcius.

c) Sorry, I cant read the Qn

[Dharma]

Drdj:

Dear tianzhu and dharma,


Thanks so much !! Appreciate your detailed explanations !!
Have scanned some further queries from various sources - hope you can help me with them - apologies for the many attachments, as I'm not sure how to do it all in 1 !!
Thanks again

http://www.postimage.org/image.php?v=PqmEMf0

Q8)

I will go for A and C. From the diagram, A looks like ice cubes with water.

If glass contains frozen ice ...NO water (melting has not taken place)...then answer is B and C.

[Dharma]

Drdj:

Dear all,


Further queries Thanks in advance

http://www.postimage.org/image.php?v=gx1amH8r

Hi

Q45b

Length of the day is determined by the time taken by the planet to make 1 rotation on its own axis while 1 revolution is the number of days taken by the planet to revolve round the Sun. There is no relationship between rotation and revolution of the planets.

[Dharma]

Drdj:

Dear all,


Further queries Thanks in advance

http://www.postimage.org/image.php?v=gx1amEEi

Q36b)

1. Machine P has the greatest ratio of radius of wheel to radius of axle of 3.0 so it will require only 5/3kg effort at the wheel to lift the 5kg load at the axle.

2. The effort is applied at the wheel (larger radius) for Machine P. So effort will move a longer distance than the load. Therefore, Machine P will require the least effort to lift the 5kg load.

Qn 36c
Machine Q has a ratio of radius of wheel to radius of axle of 2.0. It will require 2.5kg effort at the wheel to lift the 5kg load at the axle.
Machine Q has

[Dharma]

Drdj:

Dear all,


Further queries Thanks in advance
http://www.postimage.org/image.php?v=gx1amC99

The question already tells u that Sam is investigating one of the functions the roots of plants.
We know that roots absorb water for the plant. The layer of oil is to ensure that the possibility of water loss through evaporation is eliminated.
The red colouring is to enable Sam to see that water has been absorbed by the roots when the leaves turn red.

Answer - Sam is investigating if plants use their roots to absorb water.

[Drdj]

Dear Dharma,


Thanks for your explanation. However, since air can be compressed, doesn't it mean 250 cm3 of air can fit into the flask volume of 200 cm3?
Or does it mean that no matter how much air there is, the flask volume is limited??

Dharma:

Drdj:

Dear tianzhu and dharma,

Thanks so much !! Appreciate your detailed explanations !!
Have scanned some further queries from various sources - hope you can help me with them - apologies for the many attachments, as I'm not sure how to do it all in 1 !!
Thanks again

http://www.postimage.org/image.php?v=PqmEHfJ

Air will compress to occupy the max. space in the jar (200cm3)

[Drdj]

Dear Dharma,


My apologies...the question part (c) should read \"Explain the difference between in the results from the two test-tubes\". Thanks.

Dharma:

Drdj:

Dear tianzhu and dharma,

Thanks so much !! Appreciate your detailed explanations !!
Have scanned some further queries from various sources - hope you can help me with them - apologies for the many attachments, as I'm not sure how to do it all in 1 !!
Thanks again

http://www.postimage.org/image.php?v=PqmEJKS

Q46
a) To find out how different temperatures of water in which the test tube containing yeast with sugar solution is immersed affect the amount of CO2 produced by the yeast.

b) 60 degrees celcius.

c) Sorry, I cant read the Qn