The periodic table of the elements

What is the atomic number of Carbon (C)?

• 6

• 8

• 12

• 14

Which of the following elements has the highest atomic number?

• Helium (He)

• Calcium (Ca)

• Barium (Ba)

• Krypton (Kr)

Match the element to its symbol:

• Sodium

• Ca

• Potassium

• Na

• Calcium

• K

• Magnesium

• Mg

A student uses this apparatus to investigate the heat energy released when a liquid fuel is burned. This is the student's method: • measure the mass of the spirit burner and fuel. • add 100 cm³ of water to the copper can. • record the temperature of the water, • use the spirit burner to heat the water until the temperature rises by 30 °C. • immediately measure the new mass of the spirit burner and fuel. (a) Measuring the mass of the spirit burner and fuel immediately after heating the water is important because:

• it ensures the measurement reflects only the fuel burned to heat the water

• it allows the student to check if the burner is still hot

• it helps to measure the temperature of the water accurately

• it prevents the water from evaporating

The student needs to stir the mixture because:

• it helps the substances mix evenly

• it makes the mixture colder

• it changes the color of the mixture

• it increases the amount of mixture

Calculate the mean (average) temperature of the two solutions.

• 18.1°C

• 20.5°C

• 16.7°C

• 22.3°C

Oxygen can be prepared from hydrogen peroxide using a catalyst. Which is a correct statement about oxygen?

• it burns with a squeaky pop

• it relights a glowing splint

• it turns blue litmus red

• it turns limewater milky

The tables give the bond energies for the bonds broken in the reactants and the bonds made in the products. (i) Use the data in the tables to calculate the total amount of energy required to break all of the bonds in the reactants.

• energy required = 2454 kJ

• energy required = 1800 kJ

• energy required = 3200 kJ

• energy required = 2100 kJ

The aircraft carried these two liquids: • hydrazine, N2H4 • hydrogen peroxide, H2O2 When these two liquids mix in the combustion chamber, they evaporate and then react rapidly to form nitrogen gas, N2, and steam, H2O. The reaction is exothermic. The equation for the reaction is: N2H4 + 2H2O2 → N2 + 4H2O The displayed formulae for the reactants and products are shown above. (a) The tables give the bond energies for the bonds broken in the reactants and the bonds made in the products. (ii) Use the data in the tables to calculate the total amount of energy released when all of the bonds in the products are made.

• energy released = 4649 kJ

• energy released = 3240 kJ

• energy released = 5120 kJ

• energy released = 2890 kJ

Calculate the enthalpy change, ΔH, in kJ/mol, for the reaction. Include a sign in your answer.

• The answer is not provided in the image. The student is expected to calculate or provide the value based on prior information.

• ΔH = +100 kJ/mol

• ΔH = -50 kJ/mol

• ΔH = 0 kJ/mol