Basics Energy cannot be created or destroyed. However, it can be changed from one form…
Syllabus Objectives At O levels, students must be able to perform calculations involving the number…
Question Which substance contains the greatest number of atoms in 1 g?iodine (I2); iron (Fe)…
At O levels, students must be able to describe, using dot-and-cross diagrams, the formation of…
Question Sodium hydroxide reacts with sulfuric acid. The equation for the reaction is shown.2NaOH +…
When heated, two moles of X give one mole of oxygen and two moles of…
The formula of an oxide of element Y is Y2O3. 8.0 g of Y2O3 contains…
The table in the question shows details of the particles present in an atom of…
Question Acid rain contains sulfuric acid and can cause lakes to become acidic. Acidic lakes…
Question Which row shows the correct structures of the covalent molecules C2H2; hydrazine, N2H4; nitrogen,…
