IGCSE 2021 0620/23 May/June (pdf)
- A gas is released at point P in the apparatus shown.
Which gas turns the damp universal indicator paper red most quickly?
- A 1 cm3 sample of substance X is taken. This is sample 1.
X is then converted to a different physical state and a 1 cm3 sample is taken. This is sample 2.
Sample 2 contains more particles in the 1 cm3 than sample 1.
Which process caused this increase in the number of particles in 1 cm3?
- Which statement about paper chromatography is correct?
- Element X has 7 protons.
Element Y has 8 more protons than X.
Which statement about element Y is correct?
- A covalent molecule Q contains only six shared electrons.
What is Q?
- Which statement explains why metals are malleable?
- Which statement about isotopes of the same element is correct?
- The element silicon has the same structure as diamond.
Which statement about silicon is correct?
- Three ionic compounds of vanadium have the formulae V2O, VCl2 and V2O3.
What is the charge on the vanadium ion in each compound?
- In separate experiments, electricity was passed through concentrated aqueous sodium chloride
and molten lead(II) bromide.
What would happen in both experiments?
- The equation for the decomposition of calcium carbonate is shown.
CaCO3 CaO + CO2
What mass of calcium oxide is produced when 10 g of calcium carbonate is heated?
- Gas syringe X contains 100 cm3 of hydrogen bromide gas, HBr.
Gas syringe Y contains 100 cm3 of carbon dioxide gas. The volume of each gas is measured at
room temperature and pressure.
Which statement is correct?
- Which simple cell produces the most electrical energy?
- When sulfur is heated it undergoes a ……1…… change as it melts.
Further heating causes the sulfur to undergo a ……2…… change and form sulfur dioxide.
Which words complete gaps 1 and 2?
- Four statements about the effect of increasing temperature on a reaction are shown.
1 The activation energy becomes lower.
2 The particles move faster.
3 There are more collisions between reacting particles per second.
4 There are more collisions which have energy greater than the activation energy.
Which statements are correct?
- An example of a redox reaction is shown.
Zn + Cu2+ Zn2+ + Cu
Which statement about the reaction is correct?
- The equation for the decomposition of hydrogen iodide is shown.
2HI H2 + I2
Some bond energies are shown.
What is the energy change for the reaction?
- Element X forms an oxide, XO, that neutralises sulfuric acid.
Which row describes X and XO?
- Aqueous solutions of sodium sulfate and barium chloride are mixed.
Which process is used to separate a sample of barium sulfate from the reaction mixture?
- Information about element J is shown.
● Its atoms have four electrons in their outer shell.
● It is a non-metal.
● Its oxide has a macromolecular structure.
● It has a high melting point.
What is J?
- Which property is shown by transition elements?
- Helium and neon exist as monoatomic gases at room temperature and pressure.
statement 1 Helium and neon have eight electrons in their outer shell.
statement 2 Helium and neon are unreactive.
Which option is correct?
- What are possible effects of an inadequate water supply during a drought?
1 crop failure
2 wastage of water
3 human disease
4 death of farm animals
- Which statement explains why galvanising prevents iron from rusting?
- Some metal nitrates and carbonates decompose when heated strongly.
Metal Q has a nitrate that decomposes to give a salt and a colourless gas only.
The carbonate of metal Q does not decompose when heated with a Bunsen burner.
What is metal Q?
- Which compounds are released by the extraction of zinc from zinc blende and by respiration?
- Which gas is an air pollutant that causes acid rain?
- Ammonia is made from nitrogen and hydrogen. The equation for the reaction is shown.
- Which reaction does not occur during the extraction of iron from hematite in a blast Which substance is used as a catalyst in the manufacture of sulfuric acid by the Contact
- Metal X is a good conductor of electricity and is used for electrical wiring.
Metal Y is used to make an alloy which is resistant to corrosion and is used to make cutlery.
Metal Z is light and strong and is used in the manufacture of aircraft.
What are X, Y and Z?
- The formulae of two compounds of manganese are MnO2 and KMnO4.
In these two compounds the oxidation state of potassium is +1 and the oxidation state of oxygen
What are the oxidation states of manganese in each of these two compounds?
- Which statement about calcium carbonate is correct?
- Ethanol is reacted with acidified potassium manganate(VII).
Which row describes the type of reaction and the type of organic compound formed?
- The diagrams show the structural formulae of four compounds.
- Which statement about alkanes is correct?
- How much hydrogen is needed to react completely with 0.02 moles of butene to make butane?
- What is an advantage of the fermentation process for producing ethanol compared with the
catalytic addition of steam to ethene?
- The structure of a synthetic polymer is shown.
- Which substance is a natural polymer?
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