Saturday, September 29, 2007

Chemistry Questions - Redox Reaction

How about another Chemistry Question on Redox Reactions as a food for thoughts over the weekend...

Q) Which of the following conversions is a redox reaction (involves oxidation/reduction)?

A)H+ => H20
B)NO2 => NO3^-
C)SO2 => SO3^2-
D)SO3 => SO4^2-

Enjoy and take care.


Friday, September 28, 2007

Chemistry Question - Electrolysis/Mole Concept

Hey student,

Here is another one for you to think about. Yup. O Level Prelimary Chemistry question. Think about it and let me know.

Q)A certain quantity of electricity liberates 9g of aluminiun. The volume of oxygen liberated at r.t.p from dilute sulphuric acid by the same quantity of electricity is:

A)6 dm^3
B)8 dm^3
C)12 dm^3
D)24 dm^3

Happy trying. Rmbr: Best thing is to write it down and play around with the equations. You will see the light in the tunnel....


Qn answered and explained under comments

A-Math More Trigo Graphs

On the same diagram, sketch the graphs of

y=sin 3x & y=cos2x,
for x between 0 degree and 180 degree
Hence state the number of soutions to the equation
sin 3x=cos 2x
in the interval 0 degree less than or equals to x which is less then or equals to 180 degree

Click on image to have a larger view

Thursday, September 27, 2007

Chemistry Question - Bonding

Q) Since HCL has strong covalent bonds, why is it that they dissociate easily into H+ ions and Cl- ions when put in water?


In GCE O Level education, this question is usually not posed. In Junior Collleges, detailed explaination will be given in general chemistry classes.

Suggested Answer:

The hydrogen chloride molecule HCl is a simple diatomic molecule consisting of a hydrogen atom H and a chlorine atom Cl connected with a covalent single bond. Since the chlorine atom is much more electronegative than the hydrogen atom, the covalent bond between the atoms is quite polar. Consequently the molecule has a large dipole moment with a negative partial charge δ- at the chlorine atom and a positive partial charge δ+ at the hydrogen atom. In part due to its high polarity, HCl is very soluble in water (and in other polar solvents).
Upon contact with water, it immediately ionizes, forming hydronium cations H3O+ and chloride anions Cl- through a reversible chemical reaction with the water:
HCl + H2O → H3O+ + Cl−
The resulting solution is called hydrochloric acid and is a strong acid.


Wednesday, September 26, 2007

Balancing of Chemical Equations - Tips


We received an enquiry from "Vintage Deadly" for tips on balancing chemicals equations. Yes. We noticed that students in Singapore seems to be weak in Balancing of Chemical Equations and Mole Concepts.

There are indeed TIPS on balancing chemical equations, and i think schools might not have shared this TIPS - or i would just like to say - Simple Rules, to follow when balancing equations.

Rules for Balancing Equations

1. Determine the correct formulas for all the reactants and products in the reaction.

2. Write the formulas for the reactants on the left and the formulas for the products on the right with an arrow in between. If two or more reactants or products are involved, separate their formulas with plus signs.

3. Count the number of atoms of each element in the reactants and products. A polyatomic ion appearing unchanged on both sides of the equation is counted as a single unit.

4. Balance the elements one at a time by using coefficients. A coefficient is a small whole number that appears in front of a formula of an equation. When no coefficient is written, it is assumed to be 1.

5. It is best to begin with an element other than hydrogen or oxygen. These two elements often occur more than twice in an equation. Start with the Metals (Grp 1, 2 Transition metals), follows by the none metals (Grp 4-7). Oxygen atoms is the second last and Hydrogen atoms shall be the last. (Most Impt Information that is usually not shared.Not sure why also)

You must not attempt to balance an equation by changing the subscripts in the chemical formula of a substance.

6. Check each atom or polyatomic ion to be sure that the equation is balanced.

7. Finally, make sure that all the coefficients are in the lowest possible ratio

Hope this helps. Let me know if you need further assistance.


Tuesday, September 25, 2007

A-Math Trigo Qn

If p =( 1 + cosx )/sinx, 1/p= ( 1 - cosx )/( sinx ), find sinx and cosx in terms of p.

How to gain most?

first of all, we would love to thanks all those who have posted your comments, shared your thoughts, asked your questions :)

Keep them coming! we welcome all! Since O Level is coming by in 25 days time, we would love to continue to see this blog active. btw, did i mention that there are on average 100 of you viewing this blog daily? not a huge number but both me and sean are happy that there are people who visit this blog. and we will continue to provide you with tips to do well.

well, to ensure that you gain the most of out this, you yourself must participate! yeah participate is the key! ask all sorts of qns, answer qns the way u think is correct, just do it anyway! it is through participation that we can truly experience and learn at the maximum potential.

so when there are qns, have a pen and paper and work things out! see if your concepts and understanding are firm and clear.

keep the fire burning!


Monday, September 24, 2007

A-Math More P & C Qn! On forming numbers

How many even 5-digit numbers more than 50000 can be formed using the digits, 1,2,3,4,5,6,7 if no digit is to be repeated?

#1: Even
#2: 5-digit number
#3: no digit is to be repeated

Case 1:When the first digit is odd (must be more than or equal to 5)

2C1 * 5P3 * 3C1

Logic & Reasoning:

first digit: either 5 or 7 so 2C1
last digit: either 2,4 or 6 so 3C1
the remaining 3 digits can be choosen from the leftover 5 numbers so 5C1*4C1*3C1 also = 5P3

Case 2:When the first digit is even

5P3 * 2C1

Logic & Reasoning:

first digit: 6 so no need to choose just put!
last digit: either 2 or 4 so 2C1
the remaining 3 digits can be choosen from the leftover 5 numbers so 5C1*4C1*3C1 also = 5P3

Total even 5-digit numbers more than 50000 can be formed using the digits, 1,2,3,4,5,6,7 if no digit is to be repeated = Case 1 + Case 2 = 480


Application of Differentiation - Maximum/Minimum & Rate of Change

A closed box with a square base of length x and height h, is to have a volume, F, of 150m^3. The material for the top and bottom of the box costs $2 per square metre, and the material for the sides of the box costs $1.50 per square metre. Fnd the value of x and h, correct to 3 decimal places, if the total cost of the materials, C is to be a minimum.
A viscous liquid is poured onto a flat surface. It forms a circular patch which grows at a steady rate of 6cm^2/s. Find,
a) the radius r, in pie, of the patch 24 seconds after pouring has commenced.
b) the rate of increase of the radius at this instant, correct to 2 decimal places.

Done reading the qns? Do and see if your answers are correct!


Click on image for enlarged view.

Saturday, September 22, 2007

Do you know some curves are famous?

Have you heard about butterfly curve?
Wanna see its formation live?
Check them out here>>

Celebrity Curves

Click on the curves on the left hand side and see them live on the right white box.


Trouble with Integration of Ln & Expo

I seem to have trouble now with integrating ln and e.

Haha, you are having trouble because you are learning sth you don't have to know at O'Level. You don't have to know how to Integrate Ln directly.

Having said this, you note that you must know how to Differentiate Ln, e and Integrate e

For more info on how to differentiate Ln and e, refer to this post >>

Okie how to Int e
Int e^(2x+3) = e^(2x+3)/2 + c (since there are no limits given)

In short to Int e^(wadever) = e^(wadever) OVER (Differentiate wadever)

A-Math P & C Qn!

The no. of applicants for a job is 15. (i)Calculate the no. of ways in which 6 applicants can be selceted for the interview.

The six selected applicants on a particular day. (ii)Caluculate the no. of ways in which the order of the six interviews can be arranged.

Of the 6 applicants, 3 have backgrounds in business, 2 have backgrounds in education and 1 has a background in recreation. Calculate the number of ways in which the order of the 6 interviews can be arranged, when applicants having the same background are interviewed in succesion.

Who's up for this challenge?


Of the 6 applicants, 3 have backgrounds in business, 2 have backgrounds in education and 1 has a background in recreation. Calculate the number of ways in which the order of the 6 interviews can be arranged, when applicants having the same background are interviewed in succesion.


So there are 3 groups of people and there are 3! ways of arranging these 3 groups
Within BBB group, there are 3! ways of arrange these 3 B people, similar within EE group, there are 2! ways of arrange these 2E people
so Total = Arrange Big Groups * Arrange within each group = 3! * 3! * 2!

Friday, September 21, 2007

A-Math Qn Involving Ln / Log

Hi, i have a question which i can't solve it.
Qn: Peter deposited $540000 in a bank at the beginning of 1980, which gave a compound interest of 1.8% per annum, which pays directly into his bank account. After a period of t years, the amount of money that peter has in the bank was given by 540000( 1.018)^t. Find
a) the amount of money peter has at the beginning of 1993.
b) the year, in which he would have one million dollars.
If peter wants to have one million dollars in 20 years, he needs to find a bank that gives a compound interest of r% per annum. Find the value of r.

a) 1993-->1980 = 13
when t = 13, amount of $ he has = 540000( 1.018)^(13)

b)1,000 000 = 540000( 1.018)^t
1.85 = ( 1.018)^t
Either take Ln or Log on both sides of the equation ,

Ln1.85 = t Ln1.018
t=34.5 years = 35 years to have the 1 million dollars
1980 + 35 = 2015

let r be the compound interest rate
1,000 000=540000(1+(r/100))^20
1.85= (1+(r/100))^20

Taking Ln on both sides,
Ln1.85= 20 Ln(1+(r/100))

When your unknown is located in the POWER, in order to bring it down, you can either Log or Ln both sides of the equations.

Thursday, September 20, 2007

O level Chemistry Question - Mole Concept

Halo all students preparing for your O Level exams,

Do try out the following Chemistry Question from the Top 5 Sec Schools in Singapore during their Preliminary Examinations:

Q) The number of atoms in 25g of Butane is:

A. 3 X 10^23
B. 3.6 x 10^24
C. 4.2 x 10^23
D. 4.2 x 10^24

Do try and send me your answers, probably by the email or leave a comment.

All the Best

Wednesday, September 19, 2007

Drawing of Trigo Graphs

Can you give an example of a drawing of tangent graphs? For eg, 3tan2x + 1, what does each stand for and how do i go about drawing?

From the drawing, you see only 1 diagram instead of a few diagrams as what most people will have.

The secret is............ I drew my x and y axis LAST which is the reason why my diagram is so neat and it takes me less than 2 min to complete : )

Click on diagram to have an larger view

Tuesday, September 18, 2007

Amazing 3D Road Art By Julian Beever

Pavment Art

Monday, September 17, 2007

Differentiation of e

How to differentiate e^tanx?

first of all to differentiate e^anything = (Diff anything)*e^anything

so to differentiate e^tanx = (Diff tanx)*e^tanx = sec^2x*e^tanx


btw, i couldn't remember what is Diff tanx = to, but i know how to sinx & cosx
so tanx=sinx/cosx Diff using quotient rule, get the ans within 30s :)

Sunday, September 16, 2007

Emails Keep Coming In

I guess the recent earthquake tremors in Singapore are affecting my gmail as well.
My mailbox seems to have more emails as a result of the shake. LOL

It's a good sign I think. I assume more of you are seriously studying mugging harder than ever for the BIG THING. I've put a timer there if you didn't notice. 36 days and counting to the first paper, a-math.

With more emails, coming in. Pls be notified by me and "bear" might take a while to answers the questions you post. But we will be working triply hard too!

For those who know of this blog, you might want to share them with your friends as well or even better would be putting a link your blog!

You guys are pretty rather in blog designs, I've seen many creativity in you!


Pls ensure you verify your subscription.

For those who wish to be instantly informed on updates of the blog, after keying in your email address.

Within 30s, You should log into your email to check for a verfication note (it might be in your junk mail). This is the security feature to ensure that there's no spam i.e someone cant type in other's email

Read the info in the verfication email and click on the link to confirm subscription.

NO email will be sent to you unless you confirm your subscription.

Saturday, September 15, 2007

A-Math Differentiation with Ln

Qn frm email

Differentiate ln square root (2x+4)

Hint#1: Bring out Laws of Ln which is somewhat the same as Laws Of Log :)
Hint#2: When you are asked to Diff Ln (whatever) = Diff (whatever) OVER (whatever) :)


Amaths Differentiation and Integration techniques.
How to actually remember all the different ways for differentiating and Integrating, I always get mixed up

Hi xxx,

Differentiation = Decrease Power
Integration = Increase Power
(It's often sth OVER another)


Diff e^2x = 2e^2x
Integrate e^2x = (e^2x / 2)

Diff (3x+4)^5 = 5(3x+4)^4 (3)
Integrate (3x+4)^5 = (3x+4)^6/(3*6)

It's suggested that you have a "cheat" sheet with Diff on Left Hand Side and Integration on Right Hand Side.
To familiarise more, work on at least 5 qns just on differentiation and integration :)
You can always scan me any qns or type out any should you face any challenges.


Friday, September 14, 2007

A-Math Relative Velocity

R.V is challenging to most, easy for those can see,draw and understand.
I'm going to use this question to reveal the "secret" of doing R.V qn.

An aircraft flies east from A to B, where AB = 400 km. The speed of the aircraft in still air is 600 km/h and velocity of the wind is 80 km/h, blowing from the direction 048O. Find
(a) the course set by the pilot of the aircraft, giving your answer correct to one decimal place;
(b) the time taken for the journey, giving your answer correct to the nearest minute.[6]

Click on the image to view it clearly.

The "secret" is mastering R.V. is in the drawing. You must know where to draw your lines, label your lines, angles.

To order to do this, it's also important to know the terms like speed of plane in still air. Where should the value be placed?


Thursday, September 13, 2007

Kept getting F9s for all A-Math exams


There is only a month left plus left to Amath O lvls yet i keep getting F9s for all the exams. How do i pass that subject? Have tried doing TYS and practice papers, unsuccessful as i kept getting stuck at all the questions.

Hi xxx,

Good to know that you take action to be better. Since we kept getting stuck at all questions, it might signify your skills and concepts understanding are not firm yet. What I suggest you to do is to look CAREFULLY and examine the questions which you could not continue, ask yourself what is it that you cannnot do.

Is it you dont understand what the qn is asking or you dont have the basic skills in handling the qns?
Well, I can help you but you need to show me 1 question which you have done but couldn't get the answer or couldn't move on.
I will highlight to you what is it that you are lacking.


PS: Time is precious at this moment, get your teacher to help you out or a friend who you think you can trust to push you through this period.

Wednesday, September 12, 2007

A-Math Trigo Graphs

Terms you must understand

1. Amplitude
2. Period

You must be able to sketch given any trigo eqn and vice versa, i'e given graphs, find the unknowns. Just like this 2006 o level a-math p1 qn.

Note the common mistake to avoid!

If diagram appears too small for your @@s, click on the image and it will be enlarged.

Do it yourself first!

If diagram appears too small for your @@s, click on the image and it will be enlarged.

Tuesday, September 11, 2007

Why no complete answers to qns post?

Question:Why no complete answers to qns post?


1. Learning isn't about reading answers;they're about applying your knowledge to solve the questions.

2. We help students only when they take actions, regardless of the size of the action.Sending an email with the queries is an action taken. Sending qns with personal working is another massive action.

3. We believe that most of you will learn best by knowing yourself first. Knowing and recognising your strengths and weakness are important as you acknowledge them.

So if you want answers/solutions for the questions posted,take ACTION by showing us your working and we revert back to you with comments :)

No name will be published, we respect your privacy as much as our own.

Monday, September 10, 2007

Chemistry Phenomenons - Guano Kills The Bridge

As i have mentioned earlier, learning Chemistry is easy when you show aptitude and interest in the subject. Chemistry is happening around us everyday - all the phenomenons.

Below i would like to share with you on a Chemistry Phenomenon that i came across in TODAY papers dated 25th Aug 07.

Title: Did Pigeon Poo Weaken Fallen Minnesota Bridge?

I almost LOL when i read the title of this article. Interesting isn't it. Corny in a way. But after catching my breath and reading through - it is no corny anymore, it is based on scientific knowledge.

Inspectors searching for causes of the collapse of a Minnesota Bridge this month that killed at least 13 people have identified pigeon droppings as a possible factor. It is thought the build-up of Guano over many years could have speeded up the rusting of the steel beams in the eight-lane bridge, which collapsed into the Mississipi River on Aug 1.

Structural engineers had been aware of the problem as early as 1987, when inspectors noted a coating of Guano on the inside of some of the steel girders. Pigeon droppings contain Ammonia and Salt, which, when combined with rainwater, can lead to tiny electrochemical reactions that rust the steel.

"Over a long term, it might in fact cause structural weaknesses." Mr Neal Langerman, of the prestigous American Chemical Society (ACS) said.

The authorities can point to efforts to contain the problem, when screens were put up to prevent pigeons from nesting in some if the openings in the structure. But the build-up of Guano is thought to have continued on the other parts of the bridge.

Guano is just one of the factors that Inspectors are considering as they seek to prevent a repeat of the catastrophe in other ageing bridges in the United States.

Here is what i call CHEMISTRY - The World of Wonders!

Chemistry Made Easy

Learning is NEVER about memorization

I was coaching this girl who was facing some challenges with a-math; she has never passed her a-math before but the interesting thing is that she was doing all right for her e-math. well, both are math subjects, what are reasons for the difference in performance?

i was curious... pretty curious....

my curiosity was killed one day!

I was asking her a simple qn and she couldnt answer not because she wasn't smart. in fact, she's a bright girl...

i was shocked to hear her reason "i didnt bring my a-math exercise book with me, everything is in there, now i can't remember!"

then i told her " you don't have to memorize anything as formulas that are needed for provided in the formulae sheet!" the rest is understanding basic concepts! yup UNDERSTANDING....

i know some of you are already objection! objection! let me prove it to you all.

now imagine in your sci papers, you are asked the question to state the colors of rainbow. if you have learnt this in an interesting manner you will remember for life.

allow me to share with you all a story of how the color of rainbow comes about,

once upon a time, in this place called york, there lived a poor young man. his uneducated dad wanted the family to get richer, richer and called his son richer richer with the hope that his son 'richer' can fulfil his wish...

this young man was very brave despite being poor. when his place was attacked by enemies, he was the rare few who stood out, ready to be part of the warrior team. as the place york was too poor to buy more weapons, 'richer' of york gave his best in the battle against his enemies but his attempt was in vain.

however, everyone remembers the richer of york as he was one brave man who fight so bravely that even the sky was touched by his courage and when the war ended, there was a heavy rain for 3 days 3 nights. on the 4th day, everyone saw the colours on the sky. it reminded them of the brave young man


exactly like the colors of that phenomenon


Imagine i've told this story using a PowerPoint presentation with visuals, audio and even kinestatics etc, wouldn't it be powerful in helping you all recall the colors of rainbow?

this is what many are paying to learn; super memory techniques....
associating what you need to remember with something ridiculous, out of the norm, funny.... is one of the "tricks" in mastery of any subjects

so true learning is really never about memorization.
it's about finding the different tricks to enhance your understanding....

this is powerful

my teacher didnt tell me this previously! how i wish someone had share this tip with me earlier!

Sunday, September 9, 2007

Simultaneous Eqns, Vectors, Gradient of Normal, Binomial

Tips for O Level Chemistry - Metal Reactivity Series

Yoz All O Level takers,

Hope things are going fine on your side.

First of all, i would like to thank Always Lovely for inviting me to share my thoughts and experiences in the World of wonderful Chemistry, and allowing me to give-back to the academia.

Recently, i have questions asking how to memorise the Metal Reactivity Series - in order to answer numerous questions that require the knowledge of the series. I certainly believed that school teachers would have improvised their own ways of helping you to memorize the series. Some are easy while unfortunately others are tough in way (for some that dont feel connected).

My suggestion is to come up with your own "Songs" or "Riddles" in order to easily memorise it. If you have no clue on how to do it, and do not like the one given by your teachers, perharps you want to try this one out:

Potassium -> Please
Sodium -> Send
Calcium -> Charlie
Magnesium -> Monkey
Aluminium -> And
Zinc -> Zebras
Iron -> In
Lead -> Large
Copper -> Cages
Mercury -> Most
Silver -> Securely
Gold -> Guarded

Hope you will find it useful.

All the Best
Chemistry Made Easy

Saturday, September 8, 2007

How to master Physics & Chemistry without memorization

On 9/8/07, xxx wrote:
i have alot of difficulties understanding this two subject..Physics & Chemistry
is dere any easier way to rmb the points?

Hi xxx,

Learning subjects are like playing games, you need to know the rules of the games in order to play them well with good strategies certainly.

- Know definition well
- Know the formulae
- Know about Units conversion
Units conversion will help rmbr Formulae, and in turn, help to rmbr most of the definitions.
This is a skill that some school teachers have ceased to impart.

- Most Interesting of all 3 Sciences.
- Dont really have to memorise much (except QA for O Level). Rest are just based on simple concepts, and observations in life. Let's just open our minds and eyes.
- Do not skip simple chapters, bcos they will be the strings to tie up all the "more difficult" chapters. They are impt.
- Need to link them to everyday life. Indeed Chemistry is everywhere around us, if you are aware of it.

Hope this helps. Let me know if you need further assistance.

Sean Chua
Chemistry Made Easy

Friday, September 7, 2007

Chemistry Questions

From the scan in the attachment,- How do you answer question 20? How do you know how the different indicators will behave when they are mixed together?-
What's the correct answer for Q21?XXXX22. Some potassium carbonate solution is added to a sample of tap water. The mixture then appears cloudy. Which of the following ions is probably present in the sample?A) Bromide ions B) Magnesium ions C) Ammonium ions D) Sulphate ionsYea, I have no clue how to do this questionXXXX-
What is observed when hydrogen sulphide gas is reacted with iron(III) chloride solution?XXXX-
What happens when iron is heated with sodium oxide?* Hmm, for this question, isn't there like no reaction. Cause iron is less reactive than sodium right, so it won't displace sodium & won't react? Evidently I'm wrong cause it's a 5 mark question though. How?

LOL Series #1

Teacher: History is a very interesting subject. It tells you about what had happened in the past.
Student: Please teacher, I don't think I want to study history.
Teacher: Why?
Student: There is no future in it.

Teacher: Ted, if your father has $10 and you ask him for $6, how much would your father still have?
Ted: $10.
Teacher: You don't know maths.
Ted: You don't know my father!

Mother: David, come here.
David: Yes, mum?
Mother: You really disappoint me. Your results are getting worse.
David: But I will only get my report book tomorrow.
Mother: I know that. But I am going to Hong Kong tomorrow, so I am scolding you now.

Father: Why did you fail your mathematics test?
Son: On Monday, teacher said 3+5=8
Father: So?
Son: On Tuesday, she said 4+4=8 And on Wednesday, she said 6+2=8.
If she can't make up her mind, how do I know the right answer?

A mother and son were doing dishes while the father and daughter were
Watching TV in the living room. Suddenly, there was a loud crash of breaking plates,
Then complete silence. The daughter turned to look at her father.

Daughter: It's mummy!
Father: How do you know?
Daughter: She didn't say anything.

Girl: Do you love me?
Boy: Yes Dear
Girl: Would you die for me?
Boy: No, mine is undying love


Man: How old is your father?
Boy: As old as me
Man: How can that be?
Boy: He became a father only when I was born


Waiter: I've stewed liver, boiled tongue and frog's leg.
Customer: Don't tell me your problems. Give me the menu card.


Teacher: Simon, your composition on "My Dog" is exactly the same as your
brother's. Did u copy his?
Simon: No, teacher, it's the same dog!


Father: Your teacher says she finds it impossible to teach you anything!
Son: That's why I say she's no good!


Teacher: "Where were u born?"
Student: "Singapore, Sir."
Teacher: "Which part?"
Student: "All of me, Sir."
A teacher was asking her class: "What is the difference between 'unlawful'
And 'illegal'?" Only one hand shot up.
"Ok, answer, Joan" said the teacher.
"'unlawful' is when u do something the law doesn't allow and 'illegal' is
A sick eagle."

Teacher: "How come you do not comb your hair?"
Ah Kow: "No comb, Sir."
Teacher: "Use your dad's then."
Ah Kow: "No hair, Sir."


A boy came home from school with his exam results.
"What did u get?" asked his father.
"My marks are under water," said the boy.
"What do u mean 'under water'?"
"They are all below 'C' level"

Thursday, September 6, 2007

Tips for scoring in A-Math Circular Measure

Student: I can't seem to get the complicated qn on circular measure correct, there are so many formulaes to remember?

Coach: No need remember formulaes cos they're given in formulae sheet! sin rule/cos rule/area of triangle.

  1. Given a diagram, break down the diagram by re-drawing the needed portion of what the question wants >> Stay Focused
  2. Look out for Isosceles triangle or Right angle triangle.Mark out the sides which are equal in an isosceles triangle (sometimes, they form the radius of the circle). When right angle triangle is present, Pythagroa's theorem for finding length, TOA CAH SOH for angles & length. >> Look out for triangles
  3. Always see if sin rule can be applied first otherwise cos rule
  4. When evaluating arc length or area of sector, switch calculator to radian mode.

There are no formulaes to remember other than finding arc length and area of sector.



Chemistry Questions

Hi. need some help for the following questions.

Q1) What other gases is present inside a chimney besides dust, sulphur dioxide and carbon dioxide? [2 marks]Ans: carbon monoxide, oxides of nitrogen. CORRECT?

Q2) Why must a litmus paper be moist when testing for gases? [1 mark]Ans: So that the gas can dissolve in water to form its H+ or OH- ions that determines its acidic/alkaline property. CORRECT?

Q3) What apparutus is best used to transfer 125cm3 of acid into a beaker? [1 mark]Ans: Pipette or burrete?

Q4) Why can't a solution of copper (ii) oxide crystal be heated? Why must it be left evaporating and not heating? [1 mark]Ans: Because the crystals upon heating will decompose. CORRECT?

About askalwayslovely

My friend, "bear" and myself understand the amount of stress during this period of the year especially for theO Level students. so we decided to do our part to make this situation a more relaxing and pleasant atmosphere for students.

By answering all O Level A-Math, E-Math, Chemistry questions within 24-48 hours :) for free!
Email to

For those with questions, please scan or type your qns, we will reply with guidance and "secrets" in understanding the concepts. To ensure you gain the most out of this experience, it will be great if you include your workings and your thoughts on the questions.

Why us?
We have been coaching for many years so we have our strength in the subjects listed above.
Moreover, Bear is constantly talking to Scientists so his information is even more up to date!

Feel free to link my blog to yours as well :)