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O Level E Maths Tuition Singapore/Tuition O Level E Maths/Tutor

Rules for multiplying and dividing positive and negative numbers

(+)(+)= (+)
(+)/(+) = (+)

(-)(-) = (-)
(-)/(-) = (-)

(+)(-) = (-)
(+)/(-) = (-)

(-)(+) = (-)
(-)/(+) = (-)

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O-Level Singapore/O-Level/Physics and Chemistry Tuition/Physics Tutor

Petroleum

1. Petroleum is a non-renewable resource and there is only a limited amount of petroleum in the Earth.

2. Moet petroleum is used as fuel. Only a small amount is used as feedstock to make useful petrochemicals.

3. Gasohol is an alternative energy sources used as a fuel in motor vehicles.

4. Biogas is also used as an alternative energy source. It contain about 50% ethane.

5. Hydrogen can also be used as a fuel for cars.

If you need help in the Organic Chemistry, please contact Angie @96790479 or Mr Ong 98639633

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O Level Chemistry Tuition Singapore/Chemistry O Level Tuition/Tutor

Petroleum

1. Petroleum is a non-renewable resource and there is only a limited amount of petroleum in the Earth.

2. Moet petroleum is used as fuel. Only a small amount is used as feedstock to make useful petrochemicals.

3. Gasohol is an alternative energy sources used as a fuel in motor vehicles.

4. Biogas is also used as an alternative energy source. It contain about 50% ethane.

5. Hydrogen can also be used as a fuel for cars.

If you need help in the Organic Chemistry, please contact Angie @96790479 or Mr Ong 98639633

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O-Level Singapore/O-Level/Physics and Chemistry Tuition/Physics Tutor

Key Points – Practical Electricity Part 1

1. Electricity is essential in modern homes to power electrical appliances, which covert electrical energy into light, kinetic, sound and heat energy.

2. Heating elements in household appliances such as electric kettle and heater convert electrical energy to thermal energy. The heating elements are usually made of nichrome because of its high resistance and high melting point.

3. The amount of electrical energy E converted can be calculated by the following equations

E = VIt
E = (I^2)Rt
E = (V^2/R)t

V = Voltage (V)
I = Current (A)
t = Time (s)
R = Resistance (Ohm)

4. Power, P can be calculated by the following equations
P = IV
P = (I^2)R
P = (V^2)/R

5. Electrical energy consumption is measured in kilowatt hour (kWh).
One kilowatt hour is the amount of electrical energy used by 1 kW appliance in 1 hr.

If you need help in the above topics, please contact Angie @96790479 or Mr Ong @98639633

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O-Level Singapore/O-Level/Pure Physics Tuition/Physics Tutor

Key Points – Practical Electricity Part 1

1. Electricity is essential in modern homes to power electrical appliances, which covert electrical energy into light, kinetic, sound and heat energy.

2. Heating elements in household appliances such as electric kettle and heater convert electrical energy to thermal energy. The heating elements are usually made of nichrome because of its high resistance and high melting point.

3. The amount of electrical energy E converted can be calculated by the following equations

E = VIt
E = (I^2)Rt
E = (V^2/R)t

V = Voltage (V)
I = Current (A)
t = Time (s)
R = Resistance (Ohm)

4. Power, P can be calculated by the following equations
P = IV
P = (I^2)R
P = (V^2)/R

5. Electrical energy consumption is measured in kilowatt hour (kWh).
One kilowatt hour is the amount of electrical energy used by 1 kW appliance in 1 hr.

If you need help in the above topics, please contact Angie @96790479 or Mr Ong @98639633

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A-Level Biology Tuition Singapore/H2 Biology Tuition/JC Biology Tutor

TOPIC 1: CELLULAR FUNCTIONS – Part 4

LEARNING OUTCOME

(d)Analyse the molecular structure of a triglyceride and a phospholipid, and relate these structures to their functions in living organisms.

ESSAY ANSWER

Triglycerides
Triglycerides consist of one glycerol molecule and three fatty acid
molecules. The glycerol backbone is held to the fatty acids chains by ester linkages formed through condensation reactions.

The presence of numerous C-C and C-H bonds as well as being compact and
insoluble allows triglycerides to act as energy stores. Breaking the C-C and CH bonds releases energy. Due to the lower ratio of oxygen, fats yield more energy than an equal mass of carbohydrates. Oxidation of fats also yields metabolic water (twice that of an equal amount of carbohydrates).

The low density of triglycerides provides buoyancy which is important for
aquatic animals.

The hydrophobic, non-polar nature of triglycerides allows them to be stored in large amounts without affecting the water potential of cells. Triglycerides can also be used to reduce water loss from the surfaces of plants and animals, as insulation to prevent loss of heat and for electrical insulation in neurons.

Phospholipids
Phospholipids consist of one glycerol molecule, two fatty acid molecules,
one phosphoric acid molecule and, often, a variable additional group. The
glycerol backbone is joined to the fatty acid chains by ester linkages to form a fatty acid tail. The glycerol backbone is joined to phosphoric acid to form a phosphate head.

Phospholipids are major components of cell membranes. They are
amphipathic due to their hydrophilic phosphate heads and hydrophilic fatty
acid tails. In an aqueous environment, phospholipids arrange themselves into a bilayer. The heads face outwards, towards the aqueous environment on both sides of the bilayer. The tails face inwards, away from the aqueous environments. This allows them to form effective barriers between cellular contents and the external environment. The variable length and degree of saturation of the fatty acid chains allows the fluidity of the cell membrane to be adjusted. Longer chains and chains with fewer C=C bonds result in more rigid membranes while shorter chains and chains with more C=C bonds result in more fluid membranes.

Phospholipids also regulate the type of molecules entering or leaving the
cell, as the hydrophobic fatty acid tails allows only lipid-soluble molecules to pass through the cell membranes.

For exam based questions and solutions, please contact Hp @9863 9633

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A-Level Economics Tuition Singapore/H2/H1 Economics Tuition

Hi H2/H1 Economics Tuition Students

General advice from Cambridge Part 1

• Read each question carefully and make sure you know what it is asking, and what you have to do, before you begin your answer. Focus your answer on the question – do not write about something else.

° You may answer a question about inflation and write all you know about its causes and consequences, but the actual question asked wanted you to write simply about how it is measured.

° You could be told that ‘Low unemployment is one of the aims of government policy. Choose two other macro-economic aims of the government and explain what they mean.’ Some candidates may ignore the word other and explain low unemployment as one of their two aims. No marks would be given for that part of the explanation.

° For longer questions, check every so often to make sure that you are answering the question correctly.

• Look at the command words in the question. These tell you what we are looking for.

° Identify or state means you do not need to write very much – just show the examiner that you know the answer.

° Define means you need to show you understand the meaning of an economic term or topic and distinguish means you need to show you understand the differences between two or more terms.

° Describe or explain means you need to go into more detail, clearly showing you understand what something is or how something happens – ideally giving a relevant example, or using a diagram, to help your description or explanation.

° Analyse, discuss and to what extent require you to go into much more detail and your answer should be longer and include relevant examples and/or diagrams. You will usually be expected to look at something from two contrasting points of view and then come to a reasoned and well supported conclusion. Full sentences and paragraphs should be used – avoid bullet points.

• Look at the number of marks for each part of a question. This should guide you as to how long you should spend on it. Some questions will only gain you two or three marks while others may be worth as many as ten marks.

• Wherever possible, use a diagram to aid your explanations and make sure that it is accurately drawn and correctly labelled. Ensure that you refer to it in your answer and demonstrate to the examiner that you know what it shows.

Please contact Angie Hp 96790479 or Mr Ong 98639633 if you need help in Economics

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A Level GP/General Paper Tuition Singapore

Model Essay

Do libraries still play a role in our society today?

Libraries used to be a place solely containing books for you to borrow and tables and chairs for you to read these books. But with increasing competition from online shops selling books at a lower price and the presence of e-books, libraries have been differentiating themselves to be more than just a place for loaning books. Even with much more alternatives available today, it is often rare to find a deserted library in Singapore. While the traditional role of libraries may be diminishing among Singaporeans, the role of libraries remains relevant in the society. The introduction of online sources has certainly made buying and reading books largely easier than waiting for the limited quantities of each book in the library to be available to us. However, the library is still a place where reference materials are kept and these reference materials cannot be easily purchased outside. It is also still a place for parents to bring their kids to spend quality time in. The novel role today may be that the libraries are more interactive and call for participation of patrons. Hence libraries still hold a largely important role in our society.

The availability of online resources may be threatening the role of libraries in Singapore. The progression of technology has caused many things to happen at a fast pace and people are expecting that about their lives too. To purchase digital version of the book on Amazon into a mobile device now only requires minutes and it will probably be even faster in the future. This is in contrast to sourcing for a popular book in the library that requires us to check if it is currently on loan and if yes, reserving it and waiting for the borrower to return the book. Perhaps in this waiting period we could have already finished reading it if we were to order a digital version of the book. Online shops like Fishpond and Singapore Trolley have made it very easy and efficient to purchase books online. Gone are the days where you had to trudge home after borrowing 16 books during the holiday season. While many argue that the library is still a place where books are available for free, if not at a minimal cost, the tedious process puts some off from the library and dwell in the comfort of online purchasing. The role of the library is indeed threatened.

From another perspective, the library still holds a place in Singapore as it is a place where reference materials and national archives are kept. The library is extremely important to the government for such a purpose. These materials cannot be easily purchased outside of the library. Today, they are stored largely in the Lee Kong Chian Reference Library. Some of these reference materials speak of the past of Singapore, while others are important materials to know more about a certain subject. Out of print books are also present in the library and this attracts patrons to explore them. Hence, the role of the library has not changed as people still know that not all books can be bought and the library is needed for such materials.

The relevance of a library in Singapore is also displayed as the venue of choice for most families. Parents have not forgotten the conduciveness of a library to educate their children. With the prevalence of “screenagers” (a term coined to describe teenagers who spend a large amount of their time on their devices and gadgets) today, more parents are wary of offering their children with too much technology with a mobile device. Hence the library would be an apt location to bring their children back to flipping pages instead of tapping screens. This is especially so when the local government has the intention of making libraries more interactive so that children can look forward to. For example, meet-and-greet sessions of author of children’s books usually happen in the library and this draws children to reading books and knowing that the library is a fun place to be in. This mindset cultivated at a tender age is useful for the future relevance of the library even as today’s progression of technology may be causing the diminishing role of the library.

What could be a novel role of the library today is that it now involves more participation of the patrons. Enrichment courses are occasionally held in the library. Learning no longer takes place within the books in the library but also through these enrichment courses. Language classes are commonly held in the library. Literature plays are also held in the National Library of Singapore. The Esplanade Library is a place that has music studios that allow patrons to practice their music pieces. The library is no longer a place solely containing books but also an avenue where enrichment can happen beyond books and this causes them to still be able to hold relevance in today’s society.

All in all, the fast-paced society of Singapore has brought about different needs and expectations by our Singaporeans. To be able to hold a pivotal role in our society the library has to realise this and be able to adapt so as not to lag behind. Nevertheless, the library will always be a place close to our hearts and it is where the heritage of Singapore is stored in print.

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A-Level Chemistry Tuition Singapore/H2 Chemistry Tuition/JC Chemistry Tutor

Atoms, Molecules and Stoichiometry

Practice Question (15 min)

The alums are a series of double salts formed when a cation, with a charge of +1, having a large radius and a cation, with a charge of +3, having a small radius combined with sulfate ions.

Ammonium chromium alum has the formula of (NH4)aCr(SO4)b.xH2O. 1.28 g of the salt was dissolved in 100 cm3 of 0.0500 mol dm-3 ammonium chloride solution and the solution was divided into two equal portions.

To one portion was added an excess of sodium hydroxide and the mixture was boiled. The ammonia that was evolved neutralized 25.60 cm3 of 0.150 mol dm-3 nitric acid.

(a) Write a balanced ionic equation for the reaction between sodium hydroxide and the ammonium ions in solution. [1]

(b) Calculate the number of moles of NH3 from the alum. [2]

To the other portion, an excess of zinc was added which reduced the Cr3+(aq) to Cr2+(aq). The mixture was then filtered and the filtrate was titrated with acidified potassium dichromate(VI). It was found that 22.35 cm3 of 0.0100 mol dm-3 acidified potassium dichromate(VI) was required for the titration.

(c) Write a balanced ionic equation for the reaction between Cr2+ ions and acidified potassium dichromate(VI). [1]

(d) Calculate the number of moles of chromium ions from the alum. [1]

(e) Use your answer to (b) and (d), calculate the values of a and b. [1]

(f) Hence, find the relative formula mass of ammonium chromium alum and the value of x. [2]

(g) Calculate the percentage of chromium in the sample. [2]

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A-Level Mathematics Tuition Singapore/JC Maths/H2 Math Tuition and Tutor

Hi A-Level/H2 Math Students

Binomial Expansion

(1+x)^n = 1 + nx + [n(n-1)]/2!(x^2) + [n(n-1)(n-2)]/3!(x^3)……

This formula is good to memorise as it very useful for all value of x.

Note:
1. n is a negative or rational number (not positive integer). For such n, the expansion must be of the form (1+x )^n
2. The expansion has an infinite number of terms.
3. The condition lxl < 1 is very important. This ensures that the expansion is valid.

Binomial Expansion has two cases

Case 1: Expansion in terms of ascending powers of x.

Case 2: Expansion in terms of descending powers of x.

Please contact Mr Ong @9863 9633 for more detail on Binomial Expansion

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A-Level Physics Tuition Singapore/H2 Physics Tuition/JC Physics Tutor

Hi A-level/H2/JC Physics Tuition students

Mastering Qualitative Questions

Chapter 6: Thermal Physics Part 2

6. Using a simple kinetic model for matter, explain how evaporation of sweat can help in temperature control in humans. [2]

7. An ideal gas is kept in a sealed container in a car which suddenly increases in speed. Discuss whether the internal energy of the gas will increase. [2]

8. Suggest why the change in the potential energy of the gas in the balloon as it rises does not change its internal energy. [2]

9. Under what conditions does a real gas behave as an ideal gas? Explain your answer. [2]

10. For a fixed mass of ideal gas, explain using kinetic theory of gases,
(i) what happen to its pressure when its volume is reduced at constant temperature,
(ii) what happens to its internal energy when temperature is raised [4]

For the above questions models answer, please contact Mr Ong @9863 9633

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O-Level Additional Mathematics Tuition Singapore

Rule of Indices & Surds

There are 3 basic rules

Rule 1: a^m x a^n = a^(m+n)

Rule 2: a^m / a^n = a^(m-n)

Rule 3 (a^m)^n = a^(mn)

Extension of the rules

a^m x b^m = (ab)^m

a^m / b^m =(a/b)^m

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O Level E Maths Tuition Singapore/Tuition O Level E Maths/Tutor

Factors and Multiples

1. Multiples
Multiples of a number can be divided exactly by that number with no reminder.
Example:
Multiples of 3: 3,6,9,12,15……..
Multiples of 8: 8,16,24,32……..

2. Factors
Factors of a number are whole numbers that divide into the number exactly.
Example: Factors of 12 are 1,2,3,4,6,and 12

3. Common Factors
The common factors of two numbers are the factors that the numbers have in common.
Example:
Factors of 12: 1,2,3,4,6,12
Factors of 15: 1,3,5,15
Therefore common factors of 12 and 15 are 1 and 3

4. Prime Factorisation
The process of expressing a composite number as the product of prime factors is called prime factorisation.
Example
30 = 2x3x5
2,3, and 5 are the prime factors of 30

5. Highest Common Factor (H.C.F.)
The largest of the common factors is called the highest common factor.

6. Lowest Common Factor (L.C.M)
The smallest of the common multiples is called the lowest common multiple

Example
18 = 2x3x3 = 2×3^2
60 = 2x2x3x5 = 2^2x3x5

H.C.F. = 2×3 = 6
L.C.M. = 2^2 x 3^2 x 5 = 180

For Exam based questions with full worked solution. Please contact Mr Ong @9863 9633

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O-Level Singapore/O-Level/Physics and Chemistry Tuition/Physics Tutor

Key Points – DC Circuits

1. Total emf Et of n identical cells arranged in series
Et = E1 + E2 + E3 …… + En

2. Total emf Et of n identical cells arranged in parallel
Et = E1 = E2 = E3 ……+ En

3. At any point in the circuit, total incoming current is equal total outgoing current

4. The resistance of thermistors decreases as temperature increases.

5. The resistance of light-dependent resistors (LDRs) decreases as light intensity increases.

If you need help in the above topics, please contact Angie @96790479 or Mr Ong @98639633

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O-Level Singapore/O-Level/Physics and Chemistry Tuition/Physics Tutor

1. Organic compounds are compounds that contain the element carbon.

2. A hydroarbon is an organic compound that contains only carbon and hydrogen.

3. A homologous series is a family of organic compounds with the same general formula and similar chemical properties.

4. A functional group is an atom or group of atoms that gives characteristic properties to an organic compound.

5. Petrochemicals are chemical made from petroleum or natural gas.

If you need help in the above topic, please contact Angie @96790479 or Mr Ong 98639633

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