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16 questions
A substance is reduced if:
I. hydrogen is added
II. its oxidation number decreases
III. electrons are lost
IV. oxygen is lost
I and II only
II and IV only
I, II and IV only
All of the above
The reaction between chlorine water and potassium iodide solution may be represented by the ionic equation below:
Cl2(aq) + 2I-(aq) ---> 2Cl-(aq) + I2(aq)
Which of the following statements describes the reaction correctly?
I. Chlorine is the oxidising agent
II. Chlorine is more reactive than iodine
III. A reddish brown solution is formed
IV. The oxidation number of iodine increases
I and II only
II and III only
I and IV only
All of the above
Which equation does not represent a redox reaction?
2CuO(s) + C(s) ---> 2Cu(s) + CO2(g)
ZnO(s) + 2HCI(aq) ---> ZnCl2(aq) + H2O(I)
CuSO4(aq) + Zn(s) ---> Cu(s) + ZnSO4(aq)
2Fe(s) + 3Cl2(g) ---> 2FeCl3(s)
Reactions occur when dry chlorine gas is passed through heated iron fillings. Which of the following describes the change in the reaction correctly?
I. Chlorine is molecules gains electrons
II. Iron is oxidised
III. White powder is formed
IV. Chlorine is the reducing agent
I and II only
II and IV only
I, II and III only
I, III and IV only
The table shows the results of reactions between different halogens and halide solutions.
The reactivity of halogens in ascending order is:
bromine, chlorine, iodine
bromine, iodine, chlorine
iodine, bromine, chlorine
chlorine, bromine, iodine
The figure shows the manufacture of sulphuric acid by the Contact process:
Which of the following describes he change in the oxidation number of sulphur correctly?
0 ---> -4 ---> +6 ---> -6
0 ---> +4 ---> +6 ---> +6
+1 ---> +2 ---> +3 ---> +4
+2--> +4 ---> +6 ---> +8
Which of the following represent oxidation?
I. Cl2(g) ---> 2Cl-(aq)
II. Fe2+(aq) ---> Fe3+(aq)
III. Mg(s) ---> Mg2+(aq)
IV. CuO(s) ---> Cu(s)
I and III only
II and III only
I, II and III only
I, II and IV only
In which of the following reactions are copper atoms ionised to form copper(II) ions?
Copper in hot water
Copper in dilute sulphuric acid
Heated copper(II) oxide in hydrogen
Copper in silver nitrate solution
Which of the following substances oxidise iodide ions to iodine?
I. Potassium chloride solution
II. Potassium bromide solution
III. Acidified potassium dichromate(VI) solution
IV. Acidified potassium manganate(VII) solution
I and II only
III and IV only
I, II and III only
All of the above
The figure shows the apparatus set-up for electron transfer at a distance in a redox reaction.
What could be Z?
Bromine water
Iron(III) sulphate solution
Potassium iodide solution
Acidified potassium dichromate(VI)
Which of the following elements is expected to be the strongest oxidising agent?
Element W ( 2.8.3)
Element X ( 2.7)
Element Y (2.8.7)
Element Z ( 2.8.8.1)
What is the oxidation number of chromium in Cr2O72- ?
+2
+3
+6
+7
Which of the following are the most common metals used to prevent iron rusting?
Magnesium (roofing), Zinc (underground pipeline)
Tin (roofing), Magnesium (underground pipeline)
Zinc (roofing), Magnesium (underground pipeline)
Copper (roofing), Lead (underground pipeline)
Three test tubes containing different pairs of metals are left overnight and the changes are recorded as below.
Based on the observation above, which is the expected positions of metal X, Y and Z in the electrochemical series (most electropositive first) ?
X, Y, Z
Z, X, Y
Y, X, Z
Y, Z, X
Which metal oxide is most easily reduced to metal by heating it in dry hydrogen gas?
Potassium oxide
zinc oxide
Iron(III) oxide
Copper(II) oxide
Burning magnesium ribbon reacts with carbon dioxide gas
2Mg(s) + CO2(g) ---> 2MgO(s) + C(s)
What is the function of the magnesium ribbon in this reaction?
A catalyst
A reducing agent
An oxidising agent
A dehydrating agent
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