Lower Secondary Science

[Dr.033430Daniel]

Sysy:

Explain why the walls of atria are thinner than that of the walls of ventricles

Can pls help to explain the qn ?

The atria receive blood and then only distribute it a very short distance into the ventricles, so the blood inside the atria is not at a high pressure. The ventricles need to pump the blood to other parts of the body, either the lungs or the rest of the body. So the walls of the ventricles are thick and muscular to provide the pumping action and to withstand the higher pressure.

The right ventricle pumps blood to the lungs. So it has a thinner wall than the left ventricle which has to pump blood to the entire body.

[superkiasume]

anneshirleygilbert:

How do you balance this equation, please.


__Cu + __ HNO3 == __ CU (NO3)2 + __ NO2 + __ H2O

I've tried several times but can't get it.

TIA

According to the guidebook* that I am going through with my son, you should balance chemical equations in this order:
1) Metallic atoms
2) Polyatomic ions
3) Non-metallic atoms other than hydrogen and oxygen
4) Hydrogen and oxygen

So my answer is:
Cu + 4HNO3 --> Cu(NO3)2 + 2NO2 + 2H2O

*Guidebook used: Smashing Exams series.

[concerned_parent1976]

My son is given holiday assignments and the teacher give them this question which he havent learnt ,can some kind soul help me to find the answer for this and the reason why that is the correct answer ?


http://4.bp.blogspot.com/-J330LCXfae4/U3-Q8fK7eYI/AAAAAAAAAKI/QbpwxM2IGQE/s1600/question_chemistry_24may2014.png\">

[Dr.033430Daniel]

concerned_parent1976:

My son is given holiday assignments and the teacher give them this question which he havent learnt ,can some kind soul help me to find the answer for this and the reason why that is the correct answer ?


http://4.bp.blogspot.com/-J330LCXfae4/U3-Q8fK7eYI/AAAAAAAAAKI/QbpwxM2IGQE/s1600/question_chemistry_24may2014.png\">

Choice D

The liquids essentially represent two resistors in series, so both liquids must be good conductors for the bulb to light up. Mercury is a liquid metal and is highly conductive since it is a metal. The HCl will dissociate in water to form H+ ions and Cl- ions which makes the solution a good conductor.

For the other choices: In A sugar doesn't split into ions in solution, so it wont help make the water more conductive. Ethanol and propanol are not conductive as they do not split into ions, so B and C are not correct.

[hopefulparent]

I am thinking of buying the yearly TYS for my boy. He is taking the O-levels in a few months’ time.


Does anyone have any experience as to which TYS is preferable? I saw EPH, SAP, Shinglee and some other brands at Popular. Are they all the same?

Thank you.

[Dr.033430Daniel]

hopefulparent:

I am thinking of buying the yearly TYS for my boy. He is taking the O-levels in a few months' time.


Does anyone have any experience as to which TYS is preferable? I saw EPH, SAP, Shinglee and some other brands at Popular. Are they all the same?

Thank you.

The ones that are topical are good. That way the student can revise by topic. I use the ones from SAP..

[hopefulparent]

Dr.Daniel:

hopefulparent:

I am thinking of buying the yearly TYS for my boy. He is taking the O-levels in a few months' time.


Does anyone have any experience as to which TYS is preferable? I saw EPH, SAP, Shinglee and some other brands at Popular. Are they all the same?

Thank you.

The ones that are topical are good. That way the student can revise by topic. I use the ones from SAP..

Thank you for the advise, Dr Daniel.

[Bookshop]

The differences in the yearly TYS are:

1) The answer key provided. In terms of the answers provided, SAP seems to have come a long way. The answer keys used to be littered with errors here and there. But they have improved signficantly, and now generally provide answers that are more trusted than the other publishers.
2) Pricing. Popular bookshops are offering higher discounts for EPH, as it's their in-house brand.
3) Size of the book. Shinglee and EPH books are of A4 sizes, which is the O-Level standard. Also, their pages have been specially designed so that they can be torn out from the book for separate yearly revision.

You have to decide which of the above factors is the most important.

hopefulparent:

I am thinking of buying the yearly TYS for my boy. He is taking the O-levels in a few months' time.

Does anyone have any experience as to which TYS is preferable? I saw EPH, SAP, Shinglee and some other brands at Popular. Are they all the same?

Thank you.

[Bookshop]

Bookshop:

The differences in the yearly TYS are:

1) The answer key provided. In terms of the answers provided, SAP seems to have come a long way. The answer keys used to be littered with errors here and there. But they have improved signficantly, and now generally provide answers that are more trusted than the other publishers.
2) Pricing. Popular bookshops are offering higher discounts for EPH, as it's their in-house brand.
3) Size of the book. Shinglee and EPH books are of A4 sizes, which is the O-Level standard. Also, their pages have been specially designed so that they can be torn out from the book for separate yearly revision.

You have to decide which of the above factors is the most important.

hopefulparent:

I am thinking of buying the yearly TYS for my boy. He is taking the O-levels in a few months' time.

Does anyone have any experience as to which TYS is preferable? I saw EPH, SAP, Shinglee and some other brands at Popular. Are they all the same?

Thank you.

Thank you for the advise, Bookshop.

Do you have any recommendations for Physics and Chemistry revision books, where there are notes and formulas. Do you think they will be useful for last minute revision?

[Dr.033430Daniel]

hopefulparent:

Do you have any recommendations for Physics and Chemistry revision books, where there are notes and formulas. Do you think they will be useful for last minute revision?

GLM publishes Conceptual Learning Physics (red in color by Tan Ming Eng) and Conceptual Learning Chemistry (blue in color by Ong Yean Ling). These both have notes as well as example problems. They are good for revision although I never recommend \"last minute\" revision because both Physics and Chemistry require more in depth conceptual understanding to have a good shot at an A on the O'Level.

A good strategy is to start now in June and review 1-2 chapters a week. Persuading the student to follow this course though is often a challenge:) In the long run, consistency of study habits is more efficient. A person can spend less time preparing and there is a greater chance that they remember what they learn for the next level, be it JC or poly.