Chemistry calculations (O level) This post is about answering O level chemistry calculations questions which are part of stoichiometry. To fully understand these calculations you should be familiar with: how to use the periodic table relative molecular mass molar mass moles concentration valency These questions are compatible with Zimsec O level Chemistry and Combined science. …
Projectiles Revision In these questions, take g to be 10m/s2 Question 1 A particle is projected with a velocity of 30 m/s at an angle of arctan(0.75) to the horizontal. It hits the ground at a point which is level to the point of projection. Find the time for which it is in air. Solution …
Combined Science Revision Question 1 Outline how industrial gases are manufactured from air. 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 …
Impact of covid-19 on the education system The COVID-19 pandemic has a potential of becoming one other worst pandemics the world has ever seen. As such, many countries have taken the right decision to close schools, colleges and universities. Such tough decision has negative impacts on both the academic and economic fronts of any country …
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 stop them from absorbing oxygen …
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 described? Substance Bonding A Argon …
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 acid? d) Which substance could …
The importance of writing notes When asked why they are not writing notes during a lecture, many students usually reply, "I have it all right here in my textbook." Many students find note-taking tedious and pointless because they do not fully understand its merits. However creating proper study notes is an integral part of exams …
How to answer physics O level paper 2 I wrote this guide specifically for Zimsec O level Physics students but the information here can also be useful for other subjects like combined science, chemistry and biology. In fact, with little or no modification, all that is written here can apply to almost all exams that …
How to pass O level Mathematics Time yourself using past exam papers. Exams are not much about how much you know but also about how fast you can answer correctly all that you know. More than half of the students who fail mathematics fail because they run out of time before completing the papers. To …