4 marksFoundation
Some substances are listed below.
Copper, carbon dioxide, air, sodium chloride.
.1Which substance is an element?
[1 mark] .2Which substance is a mixture?
[1 mark] .3Give the number of different elements in the formula
CaCO3. .4A student has a mixture of sand and water. Choose the best method to get the sand.
[1 mark] 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]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]5 marksFoundation and Higher
A sample of copper contains two isotopes.
69.2% of the atoms are copper-63.
30.8% of the atoms are copper-65.
.1Calculate the relative atomic mass of copper in this sample.
Give your answer to 3 significant figures.
[3 marks] .2Explain why copper-63 and copper-65 have the same chemical reactions.
[2 marks] 4 marksFoundation and Higher
A student heats 2.40 g of magnesium ribbon in an open crucible. It all reacts to form 4.00 g of magnesium oxide.
2Mg+O2→2MgO.1Calculate the mass of oxygen that reacted with the magnesium.
[1 mark] .2The student says: "The mass went up, so mass was not conserved."
Explain why the student is wrong.
[2 marks] .3The student repeats the experiment in a sealed container full of air and weighs the whole container. Predict what happens to the total mass.
[1 mark] 