Silicon dioxide (silica) melts at 1710 °C. Poly(ethene) softens at about 120 °C. Methane boils at −162 °C.
Explain the differences in these temperatures.
Refer to the structure and bonding of each substance.
[6 marks]AQA GCSE Chemistry June 2024 Paper 2F
5 questions on this paper's topics
29:001 of 5
Earth's early atmosphere probably contained a lot of carbon dioxide and little or no oxygen.
.1
Explain how the amount of oxygen in the atmosphere increased.
[2 marks].2
Describe three ways the amount of carbon dioxide in the atmosphere decreased.
[3 marks]Crude oil is separated into fractions in a fractionating column.
Explain how fractional distillation separates crude oil into fractions.
[6 marks]A student investigates how the concentration of hydrochloric acid affects the rate of its reaction with magnesium ribbon. Hydrogen gas is produced.
Plan an investigation using a gas collection method.
Include the variables the student should control.
[6 marks]Sodium chloride solutions are used in hospitals.
.1
0.80 g of sodium chloride is dissolved in water to make 40 cm³ of solution. Calculate the concentration in g/dm³.
[2 marks].2
A nurse needs 250 cm³ of a solution with a concentration of 9.0 g/dm³. Calculate the mass of sodium chloride needed.
[3 marks]