How to use the periodic table In this post we are going to discuss on how to use the Periodic Table. To a random person, the Periodic Table might look like just an orderly arrangement of atoms but to a chemist, the Periodic Table is the summary of chemistry. The Read more…
Preparation of Salts (O level Chemistry) Preparation of salts depends on the physical and chemical properties of the salt. For example, when choosing the best method to prepare a salt you need to consider the following: is the salt soluble? If yes, we usually prepare it by neutralisation of acid Read more…
Combined Science Revision Solution 1 Air is cooled to -78°C. Water and carbon dioxide are removed as solids. The remaining air is further cooled by a process of rapid compression and expansion until it reaches a temperature of -200°C. At this temperature all gases are liquids except for rare gases. Read more…
Uses of common elements and compounds This is a list of commonly asked uses of substances in O level Chemistry and Combined Science exams. Uses of oxygen Medical purposes – In hospitals, oxygen is given to some people who are injured or ill with disease that damage the lungs and Read more…
Combined Science Chemistry Section Multiple Choice (Page 1) The diagram shows the electronic structure of an atom of a certain element, Z. Z will most likely form: A. Z+ ions B. Z2+ ions C. Z– ions D. Z2- ions For which one of the following substances is the bonding correctly Read more…
Mixed Revision Questions and Answers (Page 1) Question 1 Use the table below to answer the questions that follow: Substance pH A 1 B 5 C 7 D 9 E 14 a) Which substance is a weak alkali? b) Which substance could be water? c) Which substance is a weak Read more…
Metals Questions and Answers (Page 1) Question 1 Potassium is a metal above magnesium in the reactivity series. How would you expect it to react with (a) oxygen (b) water? Solution 1 (a) Reacts vigorously with oxygen (b) Reacts vigorously with water Question 2 A metal does not react with Read more…
Organic Chemistry Questions and Answers (Page 1) Question 1 The hydrocarbon methane is the first member of the alkanes homologous series. a) Draw diagrams to show the first 3 members of the alkanes homologous series. b) What substances will be formed when methane burns in plentiful air supply? How would Read more…
O level Physics and Chemistry Exam Assessment Many students find Physics and Chemistry exams tough and that is the reason why schools traditionally select only A classes only to do subjects such as chemistry, biology and physics. However anyone can do sciences. This guide will help you if you want Read more…
Important Exam Advice Important exam advice for sciences students. You cannot score marks unless you write answers but this does not mean you should spend all the time writing in an examination. It is important to read the question carefully so that you know what to answer. By knowing what Read more…