Q&A - PSLE Science

[Cockroach]

http://i56.tinypic.com/i6wi8h.jpg\"> :rahrah:

can someone help me with this post?
TIA

[Cockroach]

http://i51.tinypic.com/348kmc3.jpg\"> larger version

[atutor2001]

ss501:

hi,

pls help to explain, thanks .
http://i54.tinypic.com/30hq0ow.jpg\">

The water level in the bottle will drop because when ice changes from solid to liquid state, its volume will decrease.

There will be water droplets on the out surface of the bottle. Water vapour from the surrounding air comes into contact with the cold surface of the bottle and condenses, forming water droplets on the outer surface of the bottle.

[ss501]

hi,

pls help to explain, thanks .

http://i56.tinypic.com/155jmza.jpg\">
http://i51.tinypic.com/2rrrzw3.jpg\">
http://i55.tinypic.com/etz6sw.jpg\">

[Cockroach]

http://i51.tinypic.com/2dhto9j.jpg\">

someone help me pls
TIA

[ss501]

atutor2001:

There will be water droplets on the out surface of the bottle. Water vapour from the surrounding air comes into contact with the cold surface of the bottle and condenses, forming water droplets on the outer surface of the bottle.

@atutor: Thanks a lot

[Cockroach]

http://i52.tinypic.com/2yywjmt.jpg\">

someone help pls
TIA

[atutor2001]

ss501:

hi,

The answer given is 3, pls help to explain, thanks.
http://i56.tinypic.com/24yrc6e.jpg\">

This is the type of the question (not covered in syllabus) where the hint for the answer is given in the question. The key words are \"iron interact with oxygen\" which means iron will combine with oxygen. Therefore, the oxygen inside the tube will be used up and the volume of air inside will decrease. Hence, water will rise to take up the space previously occupied by oxygen.

About 1/5 of air is oxygen. Notice that the air above the water level is nicely divided into 5 equal parts and so answer is (3)

[atutor2001]

ss501:

hi,

The answer given is 2, pls help to explain, thanks.
http://i51.tinypic.com/egy4qc.jpg\">

Behavioural adaptation is action taken by the partridge i.e. the way they sit - facing outward, close together
Structural adaptation is how the are born with i.e. pattern on the egg shell

[atutor2001]

ss501:

hi,

pls help to explain, thanks .

http://i51.tinypic.com/2mi1a1v.jpg\">
http://i56.tinypic.com/szifds.jpg\">

By selecting T,V & X, it shows that Henry is trying to find out the effect of temperature of water on the rate of evaporation. So just specify the other factors that will affect evaporation and keep them the same :

Humidity of the surrounding air must be the same (put at same location)
Wind condition must be the same (put at same location)
Temperature of surround air must be the same (put at same location)