When radioactive isotopes decay, they sometimes have to go through a succession of disintegrations to reach a stable isotope. These are called decay chains, and involve the successive emission of…

Which two of the following are produced by the complete combustion of fuels? 1 CH42 CO3 CO24 H2O5 He6 NH3 Answer: 10) D Be careful! It specifies “complete combustion of fuels”.…

Which one of the following correctly completes the statement: During the process of evolution, natural selection will favour individuals with… Answer: 9) B A – WrongA gene pool consists of…

A children's game is played on a square grid starting in the centre. Players spin two spinners to decide how to move their counters. The first spinner decides the direction…

The depth of water in a particular tidal harbour varies with time as shown in the graph: If the variation in depth caused by the effect of the tide is…

Carbon, in the form of coke, is used to reduce iron oxide in a blast furnace. The three stages are shown below:1 C + O2 → CO22 CO2 + C…

The following statements are about hormone levels and their effect:1 Increasing levels of insulin cause an increase in blood glucose levels.2 Increasing levels of oestrogen increases the thickness of the…

I have two containers with different capacities. Initially, the larger one is full of water and the smaller one is empty. I pour water from the larger container into the…

In a laboratory experiment, protactinium-234 undergoes radioactive decay by β-emission into uranium-234. The table below describes how the mass of uranium-234 present in the sample varies with time from the…

A compound of iodine and oxygen contains 63.5g of iodine and 20.0g of oxygen. Which of the following would be its formula? Answer: 2) E We need to use the…