IGCSE 2019 4CH1/1C June (pdf)
- The diagram shows part of the Periodic Table, with elements represented by the
letters L, M, Q, R and T.
The letters in the diagram represent elements but are not their chemical symbols
(a) Give the letter from the diagram that represents a noble gas.
(b) Elements L and M are in the same group.
State why they have similar chemical reactions
(c) An atom of element Q has 31 protons.
Use this information to explain how you can determine the number of protons in
an atom of element R.
- A student does these two tests on a solution made from a white solid.
- flame test
- add acidified silver nitrate solution
The table shows his results
(a) Give the formula of the ion that produces the red flame.
(b) Name the cream precipitate.
(c) Identify the white solid.
(d) The student uses a clean metal wire in the flame test.
(i) State why the wire should be clean when used in the flame test
(ii) The table lists properties of some metals.
Add ticks to the table to show the two properties needed in a metal wire
used in a flame test.
- A student uses this apparatus to investigate the colours in four different inks, A, B, C and D.
(a) Explain two mistakes the student made when setting up his experiment
(b) Another student does the experiment but does not make any mistakes.
The diagram shows her results.
(i) State how many colours ink D contains.
(ii) State which of the inks tested could be mixed together to make ink D.
(iii) Explain which of the inks tested is insoluble in water.
- In 1937 an airship full of hydrogen gas flew from Germany to America.
(a) Which property of hydrogen makes it a suitable gas to use in an airship?
(b) Explain why helium is now used in airships instead of hydrogen
(c) Hydrogen is used to manufacture ammonia, NH3
Hydrogen is reacted with nitrogen using an iron catalyst.
(i) Give a chemical equation for this reaction.
(ii) State why a catalyst is used in this reaction.
- The reactions of metals with water and with dilute sulfuric acid can be used to determine
the order of reactivity of the metals.
The table shows the reactions of four metals, W, X, Y and Z, with water and with
dilute sulfuric acid.
(a) What is the order of reactivity of these metals?
(b) (i) State which metal, W, X, Y or Z, could be copper.
(ii) State which metal, W, X, Y or Z, could be magnesium.
(c) A displacement reaction can also be used to decide the order of reactivity of two metals.
State two observations made when an excess of magnesium powder is added to
an aqueous solution of copper(II) sulfate.
- Ethene (C2H4) can be converted into chloroethene (C2H3Cl) in a two-stage process.
(a) The first stage is to convert ethene into 1,2-dichloroethane, C2H4Cl2
Ethene is reacted with hydrogen chloride and oxygen.
Complete the chemical equation for this reaction
(b) In the second stage, 1,2-dichloroethane is converted into chloroethene.
C2H4Cl2 → C2H3Cl + HCl
This is a thermal decomposition reaction.
State what is meant by the term thermal decomposition.
(c) The diagram shows the displayed formula of chloroethene.
(i) State why chloroethene is described as an unsaturated compound.
(ii) Describe a test to show that chloroethene is unsaturated.
(d) Name the polymer formed from chloroethene.
- Halon 1301 is a compound used in some fire extinguishers.
Halon 1301 has the percentage composition by mass of
C 8.05% Br 53.69% F 38.26%
(a) Show, by calculation, that the empirical formula of this compound is CBrF3
(b) The diagram shows the displayed formula of a molecule of Halon 1301.
Draw a dot-and-cross diagram to show all the outer electrons in this molecule.
(c) The boiling point of Halon 1301 is −58°C.
Explain why Halon 1301 has a low boiling point.
- (a) There are three isomers with the molecular formula C5H12
One of these isomers is pentane.
The displayed formula for pentane is
(i) State what is meant by the term isomers
(ii) Draw the displayed formula for another isomer of C5H12
(b) Pentane reacts with bromine in the presence of ultraviolet radiation.
(i) Complete the equation for this reaction
(ii) Give the name of this type of reaction.
- A salt can be made by reacting an acid with an insoluble base.
A student has a sample of copper(II) oxide.
The student uses this method.
Stage 1 pour 50cm3
of dilute sulfuric acid into a beaker
Stage 2 warm the acid using a Bunsen burner
Stage 3 add a small amount of copper(II) oxide to the warm acid and stir the mixture
Stage 4 add further amounts of copper(II) oxide until copper(II) oxide is in excess
Stage 5 filter the mixture
Stage 6 obtain crystals from the filtrate
(a) State why the acid is warmed in stage 2.
(b) State how the student would know that the copper(II) oxide is in excess in stage 4.
(c) State why the mixture is filtered in stage 5.
(d) State the colour of the filtrate obtained in stage 5.
(e) Describe how the student could obtain a pure, dry sample of hydrated copper(II) sulfate
crystals from the filtrate in stage 6.
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