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

Hi H2/H1 Economics Tuition Students

It is often observed that even when crude oil prices have fallen, the price of petrol at the petrol kiosks refuses to slide.

Discuss why changes in the price of petrol at the petrol kiosks do not always follow changes in the price of crude oil. [25]

Introduction:
• Mkt for crude oil and Mkt for petrol at petrol kiosks are 2 separate Mkts. Mkt for crude oil is an international Mkt whereas petrol kiosks are essentially operating in the domestic Mkt.

• The 2 Mkts are governed by diff DD & SS conditions though they are linked. Link – crude oil is refined to produce petrol.

Note: changes in price of petrol do not ‘follow’ changes in price of crude oil in terms of direction and magnitude.

Development:
• Why crude oil prices have fallen.
Crude oil prices are determined by global demand and supply.
Eg. global economy contract
–> global DD down
–> Pc oil down

Eg. easing of political tension in ME
–> ↑supply

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A Level GP/General Paper Tuition Singapore

To what extent does technology facilitate crime?

The media is perhaps the most powerful entity on earth today. Everyone from celebrities to politicians to the average Joe next door attempts to harness its immense power and make an impact on the community or even the entire world. Indeed, the media is becoming more influential, yet more accessible since the advent of the Internet. For better or for worse, every individual can find a platform to make himself heard. Some critics argue that this is detrimental to society as it promotes a culture of mediocrity due to the lack of “quality control” of material that the media
publishes today. However, this argument is fl awed because it assumes that selectivity no longer exists. The media is creating more opportunities to discover talent and genius, rather than creating mediocrity.

It seems difficult to deny that the greater accessibility of the media is creating mediocrity when so much of media offerings are undeniably mediocre. YouTube has certainly provided an irresistible
opportunity for anyone wanting to get their 15 seconds of fame by showcasing their various talents, imaginary or otherwise. Pop singer Rebecca Black gained widespread attention after her first single
“Friday” went viral and received more than 60 million views on YouTube in less than a week. The song received negative critical reviews for its poor lyrics and singing. This highlights the potency of social media – Facebook, YouTube, Twitter – to create overnight sensations based not on talent but the obvious lack thereof. As Brendan Behan remarked, “there is no such thing as bad publicity”; the negative reviews are secondary to the disproportionate attention given. In this sense, the media, especially the Internet, is promoting mediocrity as it gives their efforts acknowledgement, making them temporarily famous and encouraging others to do the same. Even beyond the online community, talent seems to have taken a backseat. Reality TV series such as ‘Jersey Shore’ and even ‘The Bachelor’ are far from “reality” and more of an opportunity for contestants to cause as much drama as possible. While it may be shocking that only one Bachelor couple eventually got married, perhaps it is more of an inevitability as the show is primary aimed to create tension,
catfi ghts and an altogether unrealistic expectation of romance. On such shows, contestants are chosen for their capacity to cause drama, attracting many desperate aspiring actors. Mediocrity, indeed. Even with professional actors, the media’s insatiable appetite for scandals has overshadowed the industry. Charlie Sheen gained more attention, or notoriety, for alleged drug abuse and charges of domestic violence than his Emmy-nominated role in the popular sitcom ‘Two and a Half Men’. With the media’s desire to over-expose gossip and scandals, and to a certain extent glamorising such lifestyles, the media is certainly promoting mediocrity. By giving attention, and hence credit, to things bad and undeserving, the media encourages mediocrity.

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

Atoms, Molecules and Stoichiometry Part 3

Concept: Determining Formula of compound

A metal hydroxide, M(OH)n, is one of the products formed in an electrochemical cell used to power golf trolleys. 50.0 cm3 of solution containing 0.028 mol of M(OH)n in 1 dm3 requires 21.00 cm3 of sulfuric acid for complete neutralisation. The sulfuric acid contains 0.2 g of hydrogen ions in 1 dm3.

(a) Calculate the number of moles of sulfuric acid that will react with 1 mole of M(OH)n.

H2SO4 ≡ 2H+

No. of moles of H+ in 1 dm3 = 0.2/1.0 = 0.200

[H2SO4] = 0.2002= 0.100 mol dm-3

No. of moles of H2SO4 in 21.10 cm3 = (21.00×0.100)/1000 = 2.10 x 10-3

No. of moles of M(OH)n in 50.0 cm3 = (50.00×0.028)/1000 = 1.40 x 10-3

No. of moles of H2SO4/No. of moles of M(OH)n
= 2.10 x 10-3/1.40 x 10-3
= 1.5

1 mol of M(OH)n reacts with 1.50 mol of H2SO4

(b) Hence, determine the value of n.

2M(OH)n (aq) + nH2SO4 (aq) → M2(SO4)n (aq) + 2nH2O (l)
Mole ratio: 2M(OH)n ≡ nH2SO4
M(OH)n ≡ (n/2)H2SO4
n/2 = 3/2
n = 3

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

Hi A-Level/H2 Math Students

Common Techniques complementing the Process of Integration

1. Partial Fractions

For integrals of the form ∫ f(x)/g(x) dx

where f (x) and g(x) are polynomials and g(x) can be factorised,

we can express f(x)/g(x) as partial fractions before applying the relevant integration results.

2. Factor Formulae and Double-Angle Formulae

As we often CANNOT INTEGRATE PRODUCTS and MULTIPLE POWERS of
trigonometric expressions directly, we have to use Factor Formulae, Double-Angle Formulae and other trigonometric identities to simplify them before integrating.

3. Completing the Square in Denominator

There are two type

Type 1
Non–Factorisable Quadratic Expression in Denominator with Constant Numerator

Type 2
Non-Factorisable Quadratic Expression in Denominator with Linear Numerator

4. Integration by Substitution

Many expressions may be simplified by means of a suitable substitution i.e. change of variable to recognisable forms ie. one of the standard forms.

Please contact Mr Ong @9863 9633 for more detail on integration technique

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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 4: Forces

1. For the car, motion is impossible without friction. Discuss what is meant by friction and the direction in which it acts on the car. In your answer, suggest another example where friction is useful.[3]

2. Drag is sometimes referred to as fluid friction. Describe a way in which drag and friction between solids are similar, and a way in which they differ. [2]

3. A bungee jumper momentarily comes to rest at the bottom of the dive before he springs back upward. At that moment, is the bungee jumper in equilibrium? Explain your answer. [2]

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

Key Points – Current Electricity Part 1

1. Electric current I is the rate of flow of electric charge through a cross section of a conductor

I = Q/t

Q = amount of charge in coulomb (c)
t = time in second (s)

2. SI unit for electric current is Ampere (A)

3. The direction of conventional current is from the positive end of a cell or battery to the negative end. The directional of conventional current is opposite to that of electron flow.

4. Electromotive force (e.m.f.) e of an electrical energy source is defined as he work done W by the electrical energy source in moving a unit charge around a complete circuit.

e = W/Q

5. Potential difference (p.d.) V between two points in a circuit is defined as the work done W in moving a unit charge between these two points.

V = W/Q

6. SI unit for e.m.f. and p.d. is volt (V)

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

Ammonia – Important Definitions

1. A reversible reaction is a chemical reaction that can proceed in both the forward and reverse directions.

2. Haber process is an industrial process for making ammonia from nitrogen and hydrogen.

Operating conditions in the Haber process
Temperature – 450 deg C
Pressure – 200 – 300 atm
catalyst – Finely divided iron

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

Ammonia – Important Definitions

1. A reversible reaction is a chemical reaction that can proceed in both the forward and reverse directions.

2. Haber process is an industrial process for making ammonia from nitrogen and hydrogen.

Operating conditions in the Haber process
Temperature – 450 deg C
Pressure – 200 – 300 atm
catalyst – Finely divided iron

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

[adminMember]

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

Key Points – Current Electricity Part 1

1. Electric current I is the rate of flow of electric charge through a cross section of a conductor

I = Q/t

Q = amount of charge in coulomb (c)
t = time in second (s)

2. SI unit for electric current is Ampere (A)

3. The direction of conventional current is from the positive end of a cell or battery to the negative end. The directional of conventional current is opposite to that of electron flow.

4. Electromotive force (e.m.f.) e of an electrical energy source is defined as he work done W by the electrical energy source in moving a unit charge around a complete circuit.

e = W/Q

5. Potential difference (p.d.) V between two points in a circuit is defined as the work done W in moving a unit charge between these two points.

V = W/Q

6. SI unit for e.m.f. and p.d. is volt (V)

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

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O-Level Additional Mathematics Tuition Singapore

Objective:
Solve 2 simultaneous linear equations using either elimination or substitution method.

Elimination Method
Step 1
Eliminate one unknown first by equating (multiply or divide) and cancelling out (add or substract) an identical term.

Step 2
Solve the equation for the remaining unknown

Step 3
Substitute the solution obtained in step 2 into any one of the equations to solve for the eliminated unknown.

Step 4
Checking
Substitute both solutions into the other equation and check that
RHS = LHS

Stop & Think
3x – 4y = 11
7x – 5y = 4

Ans x = -3 and y = -5

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

Law of Arthmetic

1. Commutative law
a + b = b + a
ab = ba

2. Associative Law
a + (b+c) = (a+b) + c
a(bc) = (ab)c

3. Distribution Law
a(b+c) = ab + ac
a(b-c) = ab -bc

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

TOPIC 1: CELLULAR FUNCTIONS – Part 1

LEARNING OUTCOME

(a) Describe and interpret drawings and photographs of typical animal and plant cells as seen under the electron microscope, recognising the following membrane systems and organelles: rough and smooth endoplasmic reticulum,Golgi body, mitochondria, ribosomes, lysosomes, chloroplasts, cell surface membrane, nuclear envelope, centrioles, nucleus and nucleolus. (Knowledge of the principles of TEM and SEM are not required.) (For practical assessment, students may be required to operate a light microscope, mount slides and use a graticule.)

ESSAY ANSWER

Cell surface membrane
The cell surface membrane is a single membrane found at the periphery of
the cell. Vesicles may be seen forming and fusing at it. Some cell membranes may have foldings.

Rough endoplasmic reticulum
The rough endoplasmic reticulum (RER) is bound by a single membrane. It
consists of a system of flattened cisternae that are interconnected with each other and is continuous with the outer membrane of the nuclear envelope. The outer surface of the RER is studded with 80S ribosomes.

Smooth endoplasmic reticulum
The smooth endoplasmic reticulum (SER) is bound by a single membrane. It
consists of a system of tubular cisternae that are interconnected with each other and is continuous with RER. It lacks ribosomes on its surface.

Golgi body
The golgi body is bound by a single membrane and consists of a series of
flattened cisternae. The cis face is where new cisternae are constantly formed by fusion of vesicles from rough endoplasmic reticulum and smooth
endoplasmic reticulum. The trans face is where the golgi body buds to form
vesicles such as lysosomes and transport vesicles. The golgi body is not
continuous with any other organelle.

Lysosome
Lysosomes are spherical vesicles bound by a single membrane. Primary
lysosomes are formed from the golgi body while secondary lysosomes are
formed when primary lysosomes fuse with endocytic vesicles or with other
organelles.

Mitochondria
Mitochondria are bound by a double membrane. The outer membrane is
smooth but the inner membrane is folded into cristae. The two membranes
enclose an intermembrane space. Within the inner membrane is the matrix,
which contains circular mitochondrial DNA, ribosomes and RNA.

Chloroplast
Chloroplasts are bound by a double membrane. Within the chloroplast is a
system of flattened sacs known as the thylakoid membrane. The membranous
system forms stacks called granum with intergranal lamellae between grana.
The thylakoid membrane encloses the thylakoid space. The stroma of the
chloroplast contains the circular DNA of the chloroplast, 70S ribosomes and enzymes.

Nucleus
The nucleus is a large, spherical or ovoid structure present in most eukaryotic cells. It is bound by a double membrane known as the nuclear envelope. Within the nucleus is genetic material in the form of chromatin. Darkly-staining heterochromatin is generally found at the inner periphery of the nucleus. Euchromatin is lightly-staining. The nucleus also contains a dense region known as the nucleolus.

Nuclear envelope
The nuclear envelope is a double membrane that has nuclear pores to allow
for transport of materials into and out of the nucleus. The outer membrane is continuous with the RER. The inner membrane is associated with
heterochromatin.

Nucleolus
The nucleolus is a large and dense region inside the nucleus. It consists of a fibrous part (pars fibrosa) and a granular part (pars granulosa).

Ribosomes
Ribosomes are non-membrane bound and consist of one large subunit and
one small subunit. Ribosomes may be found free in the cytoplasm, attached
to the rough endoplasmic reticulum or attached to the nuclear envelope.
80S ribosomes are found in the cytoplasm while 70S ribosomes are present
in the matrix of mitochondria and stroma of chloroplasts.

Centrioles
Centrioles are non-membrane bound and are a pair of rod-like structures
each made up of 9 triplets of microtubules. Centrioles are positioned
perpendicular (90°) to each other.

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

Hi H2/H1 Economics Tuition Students

(a) Explain how the concept of opportunity cost can be used to analyse the basis for trade between countries. [10]

Introduction
– Define concept of opportunity cost: cost of next best alternative foregone, usually measured in terms of goods, services and monetary value given up.
– State that a country enjoys comparative advantage over another country when it can produce a good with a lower opportunity cost in terms of other goods foregone – hence the concept of opportunity cost is used to determine a country’s comparative advantage.
– And theory of CA states that trade can benefit countries if they specialize in producing and exporting the goods in which they have a comparative advantage, ie the goods that they can produce at a lower opportunity cost relative to other countries.

Body
– Explain how two countries can benefit from trade, using a numerical worked example or using dd & ss/production possibility curves
– In either case, the following should be included:
o Assumptions of the theory: each country uses the same amount of resources that is divided equally between the production of two goods (specific egs); resources fully employed and mobile between the two goods; no transport costs; constant returns to scale in production; exchange based on barter trade
o Identify internal opportunity cost for each country’s production of the two goods, and then comparative advantage for each country with the use of context (link to factor endowment)
o Show scenario of complete specialization and explain the benefits of specialisation
o Work out terms of trade (or rate of exchange) that is mutually beneficially
o Can use PPC to illustrate but numerical figures must be incorporated to illustrate O/C
o Show gains from trade for both countries

Conclusion
• The concept of opportunity cost can be used to determine countries’ production decisions as it forms the basis of the theory of how all parties engaged in trade can benefit from specializing in and exporting the goods in which they have a comparative advantage

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A Level GP/General Paper Tuition Singapore

‘Democracy is not for everyone.’ Comment.

A comparison between the lives of people living under the tyranny of Saddam Hussein and the lives of the citizens of Singapore might lead one to conclude that all countries should adopt democracy, as it tends to ensure the welfare of the people while dictatorships tend to lead to the
encroachment of human rights. However, one must note that a good and successful democracy requires a transparent and dedicated government, sharp voters and also a level of pragmatism in society. Hence, I believe that currently, democracy may not be a suitable political model for certain countries, but countries should strive towards implementing a democratic government as it can truly engage its people to maximise a country’s potential.

A transition into democracy can lead to chaos in a country if people have vastly different viewpoints and are unable to compromise. In such cases, riots and protests by the people would only fuel a country’s slide into anarchy, thus destabilising the country. Perhaps with such negative outcomes, such countries are probably not best suited for democracy, hence the saying “Democracy is not for everyone”. For example, Thailand’s transition from an autocratic regime to a democratic constitution in the late 1990s appeared to be a shining beacon of hope for a region that badly
needed such good models. Yet, its upward transition was dogged by riots and unhappiness such that many people have wondered if an autocratic regime was perhaps better. In 2008, yellow-shirt protestors in Thailand took control of the Bangkok airport as part of their riots, upsetting business activities in the country. Such a case is also evident in post-Saddam Iraq, where many of Saddam Hussein’s former militants have banded together to cause trouble in the country and oppose government forces, exacerbating the problems Iraq already faces in its transition to democracy. With stubborn citizens who are unwilling to bring their dissent to proper channels (such as forming proper political parties instead of causing social instability), democracy may not be suitable for such
countries. Democracy would definitely not ensure peace and welfare of the citizens when such groups band together to disrupt government activities.

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

Atoms, Molecules and Stoichiometry Part 2

3. (a) Define the term mole.

The mole is defined as the amount of substance that contains the same
number of particles as there are atoms in 12 g of pure carbon-12.

(b) Why is the phrase “the mass of one mole of oxygen” ambiguous?

It is because the statement can either refer to one mole of oxygen atoms or one mole of oxygen molecules (O2). The statement can also refer to 16O or 18O isotopes.

(c) A meteorological balloon of 2 m diameter has a volume of 4.19 m3. It floats since it is given an upthrust equal to the mass of air it displaces.

Calculate:
(i) the mass of hydrogen in the balloon,

No of moles of hydrogen gas = 4190 / 23 = 182.2
Mass of hydrogen = 18.2 x 2 = 364 g

(ii) the mass of air it displaces,

Volume of air displaced = 4190 dm^3
There should be 182.2 mol of air.
Mass of air displaced = 182.2 x 29 = 5280 g

(iii) the load the balloon can carry for it just to lift off from the ground.

Upthrust = mass of air displaced = mass of hydrogen + load
Load = 5283.8 – 364. = 4919.4 = 4.92 kg

4. The reaction of silicon tetrachloride with moist ethoxyethane produces two oxochlorides with the formulae Si2OCl6 and Si3O2Cl8. When 0.10 g of one of these oxochlorides completely reacted with water, all of its chlorine was converted into chloride ions, and produced 0.303 g of silver chloride precipitate when an excess of aqueous silver nitrate was added.
Deduce the identity of the oxochloride.

AgCl Ξ Cl
No of mol of Cl in 0.303 g of AgCl
= 0.303/(108+35.5)
= 2.11 x 10-3

Relative molecular mass of Si2OCl6
= 2×28.1+16+6×35.5
= 285.2

Relative molecular mass of Si3O2Cl8
= 3×28.1+2×16+8X35.5
= 400.3

No of mole of Cl in 0.1g of Si2OCl6
= (0.1/285.2) x 6
= 2.10 x 10-3

No of mole of Cl in 0.1g of Si3O2Cl8
= (0.1/400.3) x 6
= 2.00 x 10-3

The oxochloride is Si2OCl6.

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