Many of you in Singapore will be taking your End-of-Year School Exams or GCE O-Levels Exams in less than  5 weeks time.

Let’s try out some questions for revision.

Question 1:

Describe what you would see in each of the following reactions. Name the reaction product (s) which is responsible for each observation.

(a) Ethene is bubbled into aqueous bromine

(b) Magnesium is added into Copper(II) sulfate solution

(c) Solutions of silver nitrate and sodium iodide are mixed

(d) Zinc is added to sulfuric acid

(e) Calcium carbonate is heated in a test tube

(f) Solutions of sodium hydroxide and iron (II) chloride are mixed

>> Go try it out and leave your answers in the “Comment” section below.

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Air or some like to call it Atmosphere is considered a ‘minor’ chapter in GCE O Levels Chemistry examination, so much so that many teachers do not emphasise on their existence, not to mention importance.

As described by my Sec 4 Chemistry students, many of their Chemistry School teachers:

1. Ask the students to read textbook on their own
2. Give them 1 page summary mindmap or worksheet and ask them to just memorise it
3. Never even mention that Air is part of examination

Now, i beg to differ on this. If you are an educator (teacher, HOD or tutor) or even a parent that follows closely with Ten Years Series, you would realised that questions on Air have been appearing in recent year’s GCE O Levels Chemistry Examination.

Many a times, they appear in Section A (Short Questions) of Paper 2, and commonly in the form of Tables, Charts (Pie or Bar) or even Graphs. They are Application-Based questions and require the student to apply their concepts, rather than simply regurgitate what they memorise. TAKE NOTE especially if you are aiming to ACE your Chemistry!

Students must know the essential concepts of this topic well in order to be able to understand and comprehend these application fast, and solve them in limited time in examination conditions.

Let’s check out some questions on Air (Atmosphere):

Question 1:

Unpolluted rain water has a pH of about 6. Which of the following gas causes this pH?

A. Carbon Dioxide

B. Oxygen

C. Nitrogen Dioxide

D. Sulfur Dioxide

&

Question 2:

Which gas is NOT produced when hydrocarbons are burnt in the internal combustion engines?

A. Carbon dioxide

B. Carbon monoxide

C. Hydrogen

D. Oxide of nitrogen

&

Question 3:

Powdered calcium carbonate is commonly placed near the chimneys in coal-burning power station, in order to reduce atmospheric pollution by removing the waste gases. Which waste gas will not be removed by the powdered calcium carbonate?

A. Sulfur trioxide, SO₃

B. Nitrogen dioxide, NO₂

C. Carbon monoxide, CO

D. Phosphorous (V) oxide, P₂O₅

Now is your time to do some work. Try out the questions and see how much you know about this topic.

PS: Leave your answers and any suggested solutions in the “Leave a Reply” section below.

In the previous post, we have discussed on a MCQ question on Electrolysis that requires students to:

1. Write out discharge half equations

2. Do Molar Ratio Comparisons

Question:

Which of the following requires the least  number of eletrons for discharge?

A. 2 mol of Al³⁺ (aluminium) ions

B. 5 mole of OH^- (hydroxides) ions

C. 3 mol of O^2- (oxides) ions

D. 6 mol of H⁺ (hydrogen) ions

Write your Answer and Suggested Working in the “Leave A Reply” section below.

PS: If you are not sure how to proceed, you can refer to the previous blogpost by clicking HERE