5 marksFoundation and Higher
Earth's early atmosphere probably contained a lot of carbon dioxide and little or no oxygen.
.1Explain how the amount of oxygen in the atmosphere increased.
[2 marks] .2Describe three ways the amount of carbon dioxide in the atmosphere decreased.
[3 marks] 6 marksFoundation and Higher
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]6 marksFoundation and Higher
Crude oil is separated into fractions in a fractionating column.
Explain how fractional distillation separates crude oil into fractions.
[6 marks]6 marksFoundation and Higher
A student wants to investigate how the volume of sodium hydroxide solution added to 25 cm³ of dilute hydrochloric acid affects the temperature change.
Plan an investigation the student could carry out.
Include the variables to control and how to make the results as accurate as possible.
[6 marks]6 marksFoundation and Higher
Group 1 and group 7 elements both show trends in reactivity.
Reactivity increases down group 1 but decreases down group 7.
Explain these two trends in terms of electrons.
[6 marks]