IGCSE CHEMISTRY SOLVED past paper 0620/21/O/N/22 - October / November 2022 Paper 21

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This video solves and explains Cambridge IGCSE Chemistry paper 21 October / November 2022.

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Intro: (00:00)
Question1: (00:10)
The diagram shows the changes of state between a solid, a liquid and a gas.
Question2: (01:09)
A coloured dye is separated by chromatography. One component of the dye moves a distance of 13 cm and has an Rf value of 0.86. Which distance did the solvent front move?
Question3: (01:50)
A mixture contains salt, sand and sulfur. Salt dissolves in water but not in xylene. Sulfur dissolves in xylene but not in water. Sand does not dissolve in water or xylene.
Question4: (03:42)
Which statements about isotopes of the same element are correct?
Question5: (04:37)
Which type of structure and bonding is present in an element that is malleable and conducts electricity?
Question6: (04:59)
Which statements about potassium bromide are correct? 1 It has a high melting point.
Question7: (05:33)
Which substance has a similar structure to silicon(IV) oxide?
Question8: (05:48)
Caffeine is a stimulant found in coffee.
Question9: (06:36)
4.55 g of zinc is reacted with 50 cm3 of 2.25 mol /dm3 dilute hydrochloric acid. The equation for the reaction is shown
Question10: (09:11)
In the electrolysis diagram, oxidation is occurring at electrode 1 and reduction at electrode 2.
Question11: (12:17)
When an acid is added to an alkali, the temperature of the reaction mixture rises. Which words describe this reaction?
Question12: (12:40)
Some properties of four fuels are shown. Which fuel is a gas at room temperature and makes two products when it burns in a plentiful supply of air?
Question13: (13:19)
Ethene can undergo complete combustion, as shown.
Question14: (16:12)
A student adds excess zinc to dilute hydrochloric acid at 25 C. The hydrogen gas produced is collected and measured at room temperature and pressure. The results are plotted and labelled as curve X on the graph.
Question15: (17:23)
Dinitrogen tetroxide, N2O4, is converted into nitrogen dioxide, NO2, in a reversible reaction.
Question16: (18:22)
When magnesium is heated with zinc oxide a reaction occurs. The equation is shown.
Question17: (18:41)
The diagram shows an experiment. A small volume of aqueous P is poured on to solid Q and the tap of the funnel closed.
Question18: (20:02)
Ethanoic acid reacts with water to produce an acidic solution. Which row describes the roles of ethanoic acid and water in this reaction?
Question19: (20:28)
Aqueous ammonium sulfate is made by reacting aqueous ammonia with dilute sulfuric acid.
Question20: (20:58)
Carbon forms two oxides: carbon monoxide, CO, and carbon dioxide, CO2.
Question21: (21:17)
Group II elements show the same trends as Group I elements.
Question22: (22:33)
Some information about properties of Group I elements is shown.
Question23: (23:37)
Which statements describe properties of transition elements? 1 They form coloured compounds. 2 They have variable oxidation states.
Question24: (24:01)
Which statement about the extraction of aluminium by electrolysis is correct?
Question25: (24:48)
Copper(II) nitrate and zinc carbonate are heated strongly in separate test-tubes. Which row identifies the gases produced?
Question26: (25:30)
Iron from a blast furnace can be converted to steel. Which statements about steel are correct?
Question27: (26:09)
Which metal is used to galvanise steel?
Question28: (26:23)
The diagram shows a stage in the purification of dirty water.
Question29: (26:45)
Which substance in polluted air damages stonework and kills trees?
Question30: (27:19)
Which row explains why a high temperature and an iron catalyst are used in the manufacture of ammonia by the Haber process?
Question31: (28:09)
The scheme shows four stages in the conversion of sulfur to sulfuric acid. In which stage is a catalyst used?
Question32: (28:37)
Which element has an oxide that is used as a food preservative?
Question33: (28:52)
Which substance gives off carbon dioxide on heating?
Question34: (29:09)
Which formula represents ethanol?
Question35: (29:19)
Which statement about structural isomers is correct?
Question36: (30:21)
Which formula is the same in methanol, ethanol and propanol?
Question37: (30:41)
Ethene reacts with water under suitable conditions.
Question38: (31:52)
Ethanoic acid is made by reacting ethanol with acidified potassium manganate(VII).
Question39: (32:18)
Which structure represents Terylene?
Question40: (33:02)
The equation shows the formation of a polymer called Kevlar.