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Key Points – Magnetism Part 2

7. Only repulsion can differentiate magnets from other materials.

8. Magnetisation is the process of aligning the magnetic domains in a magnetic material in order to convert it into a magnet.

9. Demagnetisation is the process of removing the magnetic properties of a magnet.

10. Soft magnetic materials are easily magnetised and lose their magnetic properties easily.

11. Hard magnetic materials are difficult to be magnetised and retain their magnetic properties much longer.

12. When a magnetic material is bought near a magnet, the magnetic material becomes an induced magnet. The magnetic material can also be magnetised by repeated stroking with a magnet or by putting it in a solenoid with a direct current.

13. A magnet can be demagnetised by heating, subjecting it to heavy ;physical impact or by slowly withdrawing the magnet from a solenoid with an alternating current.

14. The direction of the magnet field is indicated by the direction in which the compass needle points.

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

Isomerism

1. Isomerism is where two or more organic molecules have the same molecular formula but different structural formula. These different molecule are called isomers.

2. Isomers have different melting and boiling points

3. Methane, ethane and propane do not have isomers.

4. Butane has two isomers
– Butane
– Methylpropane

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

Isomerism

1. Isomerism is where two or more organic molecules have the same molecular formula but different structural formula. These different molecule are called isomers.

2. Isomers have different melting and boiling points

3. Methane, ethane and propane do not have isomers.

4. Butane has two isomers
– Butane
– Methylpropane

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/Pure Physics Tuition/Physics Tutor

Key Points – Magnetism Part 2

7. Only repulsion can differentiate magnets from other materials.

8. Magnetisation is the process of aligning the magnetic domains in a magnetic material in order to convert it into a magnet.

9. Demagnetisation is the process of removing the magnetic properties of a magnet.

10. Soft magnetic materials are easily magnetised and lose their magnetic properties easily.

11. Hard magnetic materials are difficult to be magnetised and retain their magnetic properties much longer.

12. When a magnetic material is bought near a magnet, the magnetic material becomes an induced magnet. The magnetic material can also be magnetised by repeated stroking with a magnet or by putting it in a solenoid with a direct current.

13. A magnet can be demagnetised by heating, subjecting it to heavy ;physical impact or by slowly withdrawing the magnet from a solenoid with an alternating current.

14. The direction of the magnet field is indicated by the direction in which the compass needle points.

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

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

Hi A-Level/H2 Math Students

J1 – Teaching Binomial Expansion and exam practice

J2 – Teaching Permutations and Combinations and exam practice

If you have problems in your tutorial. Math tutor in One.Tution Place can help you. Please call Mr Ong @9863 9633

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

Atoms, Molecules and Stoichiometry – Notes

Lecture Notes Outline

1 Atoms & sub-atomic particles
2 Relative masses
3 The mole and related concepts
4 Empirical and molecular formulae
5 Concentration of a solution
6 Stoichiometry
7 Volumetric analysis
8 Redox reactions
9 Balancing redox equations
10 Redox titrations
11 Precipitation titrations
12 Determination of oxidation number

1. ATOMS & SUB-ATOMIC PARTICLES
• All atoms are composed of three fundamental particles ¾ protons, neutrons and electrons. The
relative charges and relative masses of sub-atomic particles are shown in the table below.

• The atomic number of an element is the number of protons in the nucleus of an atom of that element. Each element has its own atomic number. The atomic number of a neutral atom is also equal to the number of electrons.

• The nucleon number, also known as mass number, is the number of protons and neutrons in the nucleus of an atom. Protons and neutrons are both nucleons.

• The word nuclide is used to describe any atomic species of which the proton number and the mass number are specified.

• Isotopes of an element are atoms with the same atomic number but different mass numbers (i.e. they have the same number of protons but different number of neutrons in the nucleus).
– Isotopes have the same number of electrons
the same chemical properties.
– Isotopes have different numbers of neutrons (i.e. different masses)
different physical properties.

• Most elements consist of mixtures of isotopes. The abundance of each in the mixture is called its isotopic abundance (in terms of percentages or fractions).

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A Level GP/General Paper Tuition Singapore

2. Can a belief in the supernatural be sustained in the modern world?

Key words:
Belief: To analyse how it affects one’s mental condition and actions
Supernatural: That which cannot be proven or which is ‘illogical’ e.g. ghosts, fengshui Sustained: Maintained, remaining relevant and continuing to be embraced

Modern world: The world/society today!

Question Requirements:
Student needs to demonstrate that the belief in the supernatural seems to be at odds with the context of the modern world, however the student needs to recognize that belief in the supernatural can still persist today. The student also needs to predict what the future scenario will be based on observations of the present and perhaps the past. Better scripts would deal with different forms of the supernatural not necessarily restricted to religion.

Pitfalls:
Merely discussing problems of belief in the supernatural in the modern world, or how the supernatural is not to be believed in favor of maybe science. Such scripts would also discount or overlook the keyword ‘sustained’ hence not discussing the future scenario.
Students may overly focus on discussion on religion.

Possible stands:
Yes, a belief in the supernatural can be sustained in the modern world, and how these two elements may not even necessarily contradict each other.
• Scientific theories cannot refute some supernatural beliefs
• Scientific texts can even proof the validity of certain religious beliefs/texts/supernatural beliefs
• Belief or at least interest in the supernatural continues to be a source of artistic inspiration for the arts
• Conservative and cultural practices based on belief in the supernatural continues to remain in the modern world.

No, it cannot be sustained in the modern world
• Scientific evidences have proven many supernatural beliefs to be false.
• People pride scientific proof and rational belief over supernatural beliefs which have no scientific basis.
• Prevalence of modern day philosophies like humanism instead of belief or reliance on the supernatural.

Yes, it may even gain more relevance in the modern world.
• People increasingly turn to religion to find the answers to their existentialist issues.

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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 10 Waves

1. Distinguish between longitudinal and transverse waves [1]

2. Explain why sound waves cannot be polarised while transverse wave can be polarised. [2]

3. 3 Deduce, from the definition of speed, frequency and wavelength, the equation v = f x wavelength [1]

4. 4 Two progressive sound waves, each of amplitude A and wavelength l, meet at a point such that their phase difference is 2pie.
(i) Show that the ratio of the intensity of the resultant wave to the sum of the intensities of the individual waves is 2.
(ii) Explain how the ratio in (i) is consistent with the principle of conservation of energy. [4]

5. Explain what is meant by a progressive transverse wave. [1]

6. State how a polarised transverse polarised transverse wave differs from an unpolarised transverse wave. [1]

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

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

TOPIC 1: CELLULAR FUNCTIONS – Part 8

LEARNING OUTCOME

(h)Explain the mode of action of enzymes in terms of an active site,
enzyme/substrate complex lowering of activation energy and enzyme specificity.

ESSAY ANSWER

Enzymes are biological catalysts. Their main role is to speed up chemical
reactions but remains chemically unchanged at the end of reaction. Enzymes
speed up chemical reactions by lowering the activation energy of a reaction (i.e. their mode of action). Activation energy is the energy required to make substrates react. It represents the energy barrier that has to be overcome before a reaction takes place to form products. Most metabolic reactions do not occur at useful rates because their activation energy is too great. The greater the activation energy, the slower the reaction at any particular temperature. If the activation energy of a reaction is decreased (which is the case for an enzyme-catalysed reaction), the rate of reaction would increase.

This lowering of activation energy is due to formation of enzyme-substrate
complex which is formed through the binding of the substrate to the active
site of the enzyme. Mechanisms by which enzymes decrease the activation
energy of a reaction when the substrate bind to its active site (i.e. forming enzyme-substrate complex) are: – serving as a template to position substrate molecules in the correct orientation for reaction to occur. In the absence of enzymes, there is low probability that the various substrate molecules will collide with each other in the correct orientation for a reaction to occur, and thus the rate of reaction would be very slow.

– inducing physical stress in bonds of substrate. Once a substrate
binds to the active site of an enzyme, certain bonds in the substrate
molecule may be placed under physical stress. This increases the
likelihood that the bonds will break.
– increasing substrate reactivity. When the R groups of amino acid
residues at the active site of an enzyme are very close to part of the
substrate, they can change the charge on the substrate, alter the
distribution of electrons within the bonds of the substrate or cause other
changes that will increase the reactivity of the substrate.
The active site is a crevice with a precise shape and proper charge to
contain and bind the specific substrate molecule. The active site involves
only a small part (about 3-12 amino acids) of the enzyme molecule which
consists of the ‘contact’ and ‘catalytic’ residues;

i. Contact/binding residues are responsible for the specificity of the
enzyme and form a shape that is complementary to the shape of
substrate.
ii. Catalytic residues are responsible for the ability of the enzyme to
catalyse a particular chemical reaction; acts on the chemical
bonds in the substrate.

The remaining amino acids i.e. structural residues, which make up the bulk of the enzyme, function to maintain the correct globular shape of the enzyme molecule. This is essential for the optimal function of the active site.

The formation of enzyme-substrate complex requires the binding of substrate molecules to the active site of enzymes. It is known that this binding is specific where every enzyme acts on specific substrates (also known as enzyme specificity). There are two hypotheses on the mechanisms by which enzymes act on specific substrates; which are the “Lock and Key” hypothesis, and the “Induced fit” hypothesis.

Based on “Lock and Key” hypothesis, substrate molecules have a
complementary shape to the active site of enzyme. Substrate molecules fit
into active site like a lock to a key forming the enzyme-substrate complex. Binding of substrate to enzyme gives rise to enzyme-substrate complexes. Once products are formed, they no longer fit the active site and are released into surrounding medium and thus, free the active site for further binding with substrate molecules.

Based on “Induced Fit” Hypothesis, there is dynamic interaction between
substrate and enzyme. The initial shape of active site of enzyme might not
be complementary to shape of substrate. However, binding of substrate to
the active site induces a conformational change in shape of the enzyme,
which enables more effective binding of the substrate to the active site. The catalytic amino acids are brought into their correct orientations in the active site. This enables the enzyme to perform its catalytic function more effectively.

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

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

J2 H2 Economics

Macroeconomics Lecture 6 : Inflation Part 2

6.1 Describing Inflation

There are 4 ways to describe inflation.

(a) Moderate or Mild Inflation

This type of inflation occurs when price levels are rising slowly. We might arbitrarily classify this as less than 3% annually. The consequences of mild or moderate inflation are as follows : people do not spend time trying to unload their money because its real interest rate is acceptable, inflation expectations are relatively stable, people are not afraid to write contracts in nominal terms (the opposite is people insist to write contracts where the price is indexed to inflation).

(b) Creeping Inflation

This occurs when inflation is higher than mild inflation but still less than 10% per annum.

(c) Galloping Inflation

This occurs when prices start rising at double or triple-digit rates of 20%, 100% or 200% a year. Once galloping inflation takes hold of the economy, people would index their purchases to a foreign currency. Because money loses its value so quickly, people avoid holding any more than the bare minimum. People hoard goods, buy houses; and do not have incentives to lend money at ordinary interest rates.

(d) Hyper Inflation

This is worse than galloping inflation where inflation rates are at a thousand, or a million or a trillion per cent annually. For example, Germany experienced hyper inflation in the early 1920s, as did China after the second world war, Zimbawe in 2008 (98% per day). Hyper inflation generally leads to a currency reform or a major economic collapse.

6.2 Causes of Inflation

Economists distinguish between two types of inflation so that the right remedy actions can be taken.

(a) Demand-Pull Inflation

Changes in the price level have been attributed to an excess of total demand in a period close to or at full employment. The economy may attempt to spend beyond its capacity to produce, i.e. AD increases relative to AS at, or close to full employment. The business sector cannot respond to this excess demand by expanding real output because all available resources are already fully employed. Therefore, this excess demand will bid up prices of the fixed real output, causing demand-pull inflation. In short, “too much spending chasing too few goods.”

The increase in AD may be attributed to the following :

(i) Increases in the components of AD

• Consumption expenditure increases due to consumer optimism
• Investment expenditure increases autonomously due to the opening up of export markets, technological innovations
• Government expenditure increase due to increases in national defence expenditures, increase in social needs such as education and healthcare.
• Net export income increases due to affluence abroad.

(ii) Over-issuance of Money by Central Bank

An expansionary monetary policy when the economy is at full employment will only cause price increase.

Demand-Pull Inflation may be illustrated by the following AD/AS diagram :

(b) Cost-Push Inflation

The theory of cost-push inflation explains rising prices in terms of factors that raise per-unit production costs at each level of spending. A per-unit production cost is the average cost of a particular level of output. This average cost is found by dividing the total cost of all resource inputs by the amount of output produced. That is,

Per-unit production cost = Total Input Cost / Units of Output

Rising per-unit production costs squeeze profits and reduce the amount of output firms are willing to supply at the existing price level. As a result, the economy’s supply of goods and services declines and the price level rises. In this scenario, costs are pushing the price level upward.

The sources of cost-push inflation are as follows :

(i) Wage Push
Due mainly to the power of trade unions (imperfect competition in the factor market), higher wages raises the costs of production and hence resulting in an leftward shift of the AS curve.

(ii) Profits Push
If markets are imperfect e.g. monopoly market structure, output will always be less than socially optimal level, hence AS shifts left.

(iii) Supply-side Shocks
Natural disasters or epidemics, abrupt increases in the costs of raw materials or energy inputs push up the costs of production and shifts the AS to the left.

(iv) Structural Rigidities and the Ratchet Effect
Supply side rigidities prevent the efficient reorganization of factors of production to meet changes in the demand for goods and services in the economy in the short run, causing prices to rise rapidly.

(v) Currency Depreciation
A weaker currency makes imported raw materials more expensive, thereby leading to higher costs of production. Thus, AS shifts left.

(vi) Tax Push

This occurs when an increase in indirect taxes adds to the cost of living. An example will be the introduction of a goods and services tax. Firms will increase prices and pass some of the increased costs to consumers and cut back on production, causing AS to shift to the left.

Cost-Push Inflation may be illustrated by the following AD/AS diagram :

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

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

Significant figures

Example 1
2093 = 2000 (1 sf)
2093 = 2100 (2 sf)

Example 2
5.045 = 5 (1 sf)
5.045 = 5.0 (2 sf)

Example 3
0.0854 = 0.09 (1 sf)
0.0584 = 0.085 (2 sf)

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O-Level Additional Mathematics Tuition Singapore

Simultaneous Linear Equations

Learning Objective
Solve 2 simultaneous linear equations using elimination or substitution method

Non-Linear Equations

Learning Objective
Identify non-linear equations and use substitution method to solve the equations.

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

Key Points – Magnetism Part 1

1. A magnetic field exists around a magnet.

2. A magnetic field is a region in which another magnet or magnetic material experiences a magnetic force.

3. This magnetic force is either repulsion or attraction.

4. A magnet always has a north pole and south pole. The magnetic field of a magnet is the strongest at the poles.

5. Magnetic materials are attracted to both ends of a magnet. Magnets do not affect non-magnetic materials.

6. Like poles repel while unlike poles attract.

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Alkenes

1. Alkenes are unsaturated hydrocarbons that contain one or more carbon-carbon double bond

2. The general formula of alkenes with one double bond is CnH2n

3. Naming of alkenes
Ethene C2H4
Propene C3H6
Butene C4H8

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

Alkenes

1. Alkenes are unsaturated hydrocarbons that contain one or more carbon-carbon double bond

2. The general formula of alkenes with one double bond is CnH2n

3. Naming of alkenes
Ethene C2H4
Propene C3H6
Butene C4H8

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

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