Q&A - PSLE Science

[ApronMama]

csc:

Hi Vanilla Cake,


Upon heating a beaker of water, some bubbles will be seen escaping from the water - those bubbles contain AIR.

If we continue heating the beaker of water until it starts to boil - the water should be bubbling and larger bubbles are seen escaping from it. These bubbles now contain STEAM as water is changed into steam at boiling point.

This is what I gathered a few years back when my son asked the same question in Pr 4. Hope it helps.

Just to be sure : steam is not air at boiling point but water droplet (liquid)form when water vapour at boiling point condense due to heat lose when contacting the surrounding room temperature. (correct me if I am wrong)

[csc]

ApronMama:

Just to be sure : steam is not air at boiling point but water droplet (liquid)form when water vapour at boiling point condense due to heat lose when contacting the surrounding room temperature. (correct me if I am wrong)

Steam in NOT water droplets but it is actually hot water vapour which is formed when water boils. If steam condenses on contact with a the colder surrounding temperature, it will become tiny water droplets known as mist. And air is a mixture of gases of which water vapour is one of it.

[tianzhu]

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When the water filled up, the candle would be raised up closer to the spiral. Hot air rises causing the spiral to twirl/spin.

In this question, we assume that the candle must be of a reasonable distance from the spiral before the rising hot air can cause it to spin
Let’s take it a bit further, if the candle is placed nearer to the spiral, will the spiral spin faster or slower. Please explain your answer. I am not sure whether this has been asked before.

[tianzhu]

Thank you for your time.

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[tianzhu]

tianzhu:

Evaporation and Condensation


Your loving mother put some hot Tiong Bahru Paos (buns) in a transparent plastic hood. After a few minutes , water droplets are observed to be formed on the inner surface of the hood. Is it right to say that hot water vapours from the paos (buns) condensed into water droplets when they touched the cooler interior surface.

Finally, I can find some logical explanation to show where does the water vapour of the paos come from.It may come from the dough used to make the pao skin(water is mixed with flour) and perhaps water used in mixing internal fillings.During the steaming of the paos at an earlier time,water had been absorbed.

[tianzhu]

tianzhu:

Thank you for your time.

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I got some help from another site(onsponge),the following link may help in answering this interesting diving question.
http://www.popsci.com/node/23385

[tianzhu]

Some useful Science websites.


http://www.howstuffworks.com/
http://www.sciberdiver.edu.sg/default.asp
http://classroom.jc-schools.net/sci-units/

You may want to add more to the list.Any recommendation?

[dedi]

[Moderator's note: Topics merged.]


Anyone can confirm if this year's PSLE Sci paper will be based on new or old syllabus?

The new sci syllabus omits topics like the Solar System and Simple Machines. So do students need to revise such topics for their PSLE? Anyone has any idea when will PSLE Sci incorporate the new syllabus? :?

[tianzhu]

dedi:

Anyone can confirm if this year's PSLE Sci paper will be based on new or old syllabus?


The new sci syllabus omits topics like the Solar System and Simple Machines. So do students need to revise such topics for their PSLE? Anyone has any idea when will PSLE Sci incorporate the new syllabus? :?

PSLE Science 2009 is still using the old syllabus. The Solar system and Simple machines are included.Only P6 students are still using the old textbooks. Those in P5 and below are using the new textbooks(lower block/upper block)

[matrix0405]

It still the old syllabus. The PSLE 5-year series are out, make sure you get a copy.