Q&A - P5 Science
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cftan:
Impurities can lower the melting point of a substance or raise its boiling point.How impurities can affect the melting point?
a)the melting point is raised.
b) it lowers the melting point.
Which is correct? Or both acceptable? -
dioprem:
Son's answer is : when impurities is added, the boiling point is raised, the melting and freezing point are lowered.
Impurities can lower the melting point of a substance or raise its boiling point.cftan:
How impurities can affect the melting point?
a)the melting point is raised.
b) it lowers the melting point.
Which is correct? Or both acceptable?
But teacher corrected as: boiling and melting is raised, freezing point is lowered.
So confusing... -
dioprem:
Son's answer is : when impurities is added, the boiling point is raised, the melting and freezing point are lowered.
Impurities can lower the melting point of a substance or raise its boiling point.cftan:
How impurities can affect the melting point?
a)the melting point is raised.
b) it lowers the melting point.
Which is correct? Or both acceptable?
But teacher corrected as: boiling and melting is raised, freezing point is lowered.
So confusing... -
cftan:
Son's answer is : when impurities is added, the boiling point is raised, the melting and freezing point are lowered.
Impurities can lower the melting point of a substance or raise its boiling point.dioprem:
[quote=\"cftan\"]How impurities can affect the melting point?
a)the melting point is raised.
b) it lowers the melting point.
Which is correct? Or both acceptable?
But teacher corrected as: boiling and melting is raised, freezing point is lowered.
So confusing...[/quote]You son is actually correct. Freezing point is actually melting point. So the teacher's answer is contradicting when she says that melting point is raised while freezing point is lowered when they are the same.
However there are some exceptions where the substances melting point is actually different from its freezing point, but that is not covered even in the O level syllabus. Quite sure it isn't covered in the A level syllabus as well. -
dioprem:
Son's answer is : when impurities is added, the boiling point is raised, the melting and freezing point are lowered.
Impurities can lower the melting point of a substance or raise its boiling point.cftan:
How impurities can affect the melting point?
a)the melting point is raised.
b) it lowers the melting point.
Which is correct? Or both acceptable?
But teacher corrected as: boiling and melting is raised, freezing point is lowered.
So confusing... -
Thank you, dioprem. Will clarify with teacher again.
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Hi all,
Can I check if anyone has children in Pri 5 whose school CA/SA papers had tested on osmosis before? It basically showed a Visking tubing containing starch solution in a test tube containing iodine, and then ask what will happen.
tks… -
It’s quite a common question.
Although osmosis is not in the syllabus,
the idea of a visking tubing being like the
cell membrane is always tested. -
No test but it was in her worksheet.
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Thanks!
Then it raises the question as to why is it (osmosis) not in the pri sci syllabus if it is so relevant.
It’s upsetting as students are tested more and more on out-of-syllabus knowledge. If MOE feels that some topics are too early for Pri Sch, then why is it that knowledge related to these topics is being tested on, even if it is not directly or exactly the same?
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