Chemistry Paper 1 Questions and Answers - Kijiset Revision Mock Exams 2022

« Previous Topic
Kiswahili Paper 3 Questions and Answers - Kijiset Revision Mock Exams 2022

Next Topic »
Chemistry Paper 3 Questions and Answers - Kijiset Revision Mock Exams 2022

Download PDF for future reference Get on Whatsapp for 50/-

Questions

Candidates should check the question paper to ensure that all pages are printed as indicated and no questions are missing

Element Y has atomic number 17 while X has 12.
1. Write electronic arrangement of X and Y. (1mk)
2. Name the type of bond and structure formed when X and Y reacts. (2mks)
3. Draw a dot (●) and cross (X) diagram of the compound formed in (ii) above. (1mk)
The table below indicates the PH value of solutions labelled M, L, N, P and Z.

pH 4 14 1 10 7

Solution M L N P Z
1. Which solution has the highest concentration of hydrogen ions? (1mk)
2. Which solution can be used as an anti-acid? Give a reason for your answer. (2mks)
State two reasons why luminous flame is not used for heating purposes in the laboratory (1 mk)
In which homologous series do the following compounds belong?
1. CH₃ CH CH₂ (2 marks)
2. CH₃ CH₂ CH₂ OH
The structures shown below represent two cleansing agent A and B.
1. Name the type of cleansing agent A. (1 mark)
2. Which of the two cleansing agents is more suitable for washing in water containing calcium chloride? Give a reason. (2 marks)
1. Study the nuclear equation below and answer the questions that follow.
  235 1 141 n 1
  U + n → Ba + Kr + n
  92 0 56 m 0
  1. Determine the values of (1mark)
  2. State one useful application of this type of nuclear reaction. (1mark)
2. Write an equation to show how thorium nuclide 90 Th undergoes alpha decay to form another nuclide radium Ra.
  (Clearly indicate the mass number and atomic number of radium) (1 mark)
The apparatus below were used to separate a mixture of liquid A and B.

State two properties of liquids that make it possible to separate using such apparatus. (1 mark)
1. What property of concentrated sulphuric(VI) acid is illustrated by its action on:
  1. Sugar ( ½ mk)
  2. Copper metal ( ½ mk)
2. Write the equation for the reaction of concentrated sulphuric acid with copper metal. (1mk)
Ammonia is manufactured in the Haber process according to the equation:-
N_2(g) + 3H_2(g) ⇌ 2NH_3(g)
1. How would the following affect the yield of ammonia.
  1. High pressure. (1mk)
  2. High temperature. (1mk)
  3. Name the catalyst used. (1mk)
X grams of anhydrous sodium carbonate was dissolved in water to make a 250cm3 solution. 25cm3 of the solution neutralized 20cm3 of 0.25M nitric acid. Determine the value of X. (3mks)
Study the table below and answer the questions that follow.

Bond type
C – C
C = C
C – H
C – Br
Br – Br Bond energy KJmol^-1
346
610
413
280
193
1. Calculate the heat change for the reaction;
  C₂H₄ + Br₂ → C₂H₄Br₂ (3mks)
2. Name the type of reaction that occurred in (a) above. (1mk)
The Solvay process is used to manufacture Sodium Carbonate.
1. Name two raw materials for the process. (1mk)
2. How is Sodium Carbonate obtained from Sodium Hydrogen Carbonate? (1mk)
3. Name two main substances that are recycled. (1mk)
Starting with copper turning, describe how a solid sample of Copper (II) Carbonate can be prepared. (3mks)
The diagram below represents the apparatus used to react steam with magnesium.
1. State the observation made in the boiling tube. (1mk)
2. Write an equation for the reaction that takes place in the tube. (1mk)
3. What property makes it possible for gas C to be collected as shown? (1mk)
The following diagrams shows the structure of two allotropes of carbon. Study them and answer the questions that follow.
1. Name the allotropes. (1 mark)
2. Give one use of A. (½ mark)
3. Which allotrope conducts electricity? Explain. (1½ marks)
The diagram below represents an arrangement for preparing and collecting dry hydrogen. Study it and answer the questions that follow.
1. Write the equation for the reaction that produces hydrogen gas. (1mk)
2. Name the suitable substance that liquid K is likely to be. (1mk)
3. Explain why it is not advisable to use nitric (v) acid as an alternative to hydrochloric acid in the preparation experiment. (1mk)
Explain what happens when blue litmus paper is dipped in methylbenzene in which hydrogen chloride is bubbled. (2mks)
Using equations only differentiate the bleaching effect of Chlorine and SO2 (2mks)
In temperate countries, salt is sprayed on roads to defrost and clear roads but the long term effect on this practice is costly to motorist.
1. Explain the role of salt in defrosting the ice. (1mk)
2. Explain why the long term effect is costing to motorist. (1mk)
1. State Graham’s gas law of diffusion. (1mk)
2. Two containers, one with Nitrogen (IV) oxide and other with bromine simultaneously develop leaks, after 30 seconds, the smell of Nitrogen (VI) oxide is detected. How much longer will it take before bromine is detected. (N = 14, O = 16, Br = 80) (2mks)
Study the diagram below and answer the questions given below.
1. The reaction between ammonia and oxygen in the presence of the catalyst continues without further heating. Explain. (1mk)
2. Name catalyst X. (1mk)
3. Write an equation for the reaction which takes place in the flask. (1mk)
A current of 0.4 A was passed through lead (II) nitrate solution for 30 minutes. Determine the mass of lead deposited. (Pb = 207 1F = 96500C ) (3mks)

The table below shows the tests carried out a sample of water and the results obtained.

Sample	Tests	Observation
A	Addition of sodium hydroxide solution dropwise until in excess	White precipitate which dissolves in excess to form colourless solution
B	Addition of excess aqueous ammonia	White precipitate
C	Addition of dilute nitric (V) acid followed by barium chloride	White precipitate

Identify the anion present in the water. (1mk)
Write the ionic equation for the reaction in C. (1mk)
Write the formula for the complex ion in A. (1mk)

An ore of iron was found to contain 7g of iron and 3g. of oxygen.
( Fe = 56 O =16)
1. Work out its empirical formula. (2mks)
2. Write a balanced equation for reaction of the oxide in (a) with hot carbon. (1mk)
1. Name the two common ores from which Zinc metal can be extracted. (1mk)
2. Taking one of the ores named in (a) above, write a chemical equation for the roasting process to get the required oxide. (1mk)
3. Outline any two uses of Zinc metal. (1mk)
One of the four types of oxides is amphoteric oxide.
1. What is an amphoteric oxide? (1mk)
2. Write the formulae of any two amphoteric oxides. (1mk)
Rusting leads to fast wearing out of farm tools and equipment as well as buildings.
1. Give the chemical name of rust. (1 mark)
2. What two conditions accelerate rusting process? (2 marks)
The melting point of phosphorous(III)chloride is -91°C while that of sodium chloride is 801°C. In terms of structure and bonding explain the difference in the melting point. (3mks)
1. Define the term molar latent heat of fusion. (1 mark)
2. The molar heat of fusion of ice at O0C is 6kJ mol-1. Calculate the heat change when 36g of ice is converted to 36g of water at 100C. (3 marks) (SHC = 4.2Jg-1 K^-1, density = 1.0g/cm³, H = 1.0, O = 16.0)

Marking Scheme

1. X 2.8.2
  Y 2.8.7
2. ionic bond
  giant ionic structure
1. N
2. P – it is a weak base
It produces less heat 1 mk
Makes apparatus dirty
Alkene
Alkanols 1mk
1. Soap / soapy detergent
2. B ( 1)– does not form scum with hard water / economical( 1)
1. 1. n = 92
    m = 36
  2. Production of energy or electricity for domestic and industrial use.
2. 228 224 4
  Th → Ra + He or ( ∝ )
  90 88 2
Immiscible
Different densities
1. 1. Dehydration ( ½ )
  2. Oxidation ( ½ )
2. Cu(s) + 2H2SO4(l) CuSO4(aq) + SO2(g) + 2H2O(l) (1)
1. 1. Yield increases; volume of the reactants higher than volume of the product. (1mk)
  2. Yield decreases; high temperature favours backward reaction. (1mk)
2. Finely divided iron. (1mk)
Na2CO3 + 2HNO3 → 2NaNO3 + H2O + CO2
Moles of HNO3 + 2HNO3 = 20/1000 x 0.2 = 0.005
Moles of Na2CO3 = 0.005 x 1/2 = 0.0025
Molarity Na2CO3 = 0.0025 x 1000 = 0.1M
25
1 mole Na2CO3 = 23 x 2 + 12 + 16 x 3 = 106g
0.1 Mole = 0.1 x 106 = 10.6g
x = mass M 250cm³ = 250 x 10.6 = 2.65g
1000
1. H H H H
  | | | |
  C = C + Br - Br → Br - C - C - Br
  | | | |
  H H H H
  Breaking of C= c bond + 610 KJ
  Breaking of Br-Br Bond = 193 KJ 1
  Formation of 2c – Br Bond = - 280 x 2 KJ
  243KJ
2. Addition reaction
1. Brine ( conc. Sodium Chloride Solution ) NaCl (aq)
  Ammonia gas NH_{3 (g)}
  Calcium Carbonate CaCo3
  Any 2
2. Heating
3. Ammonia and Carbon (IV) Oxide 1
  Reject water.
Add excess copper turnings to 50% nitric acid. Filter to obtain Copper (II) Nitrate solution. Add Sodium Carbonate Solution and Copper (II) Carbonate will precipitate. Filter and allow the residue to dry.
1. A Bright white flame and a white powder✓1
2. Mg_(s) + H₂O_(g) → MgO_(s) + H_2(g)
3. Gas C is Insoluble in water ✓1
1. A – Diamond ✓½
  B – Graphite ✓½
2. Drilling metals . Any ✓½
  Jewelling.
3. B ✓½ Existence of delocalised electrons ✓½ which conduct electric current. ✓½
1. Zn_(s) + HCl_(aq) → ZnCl_2(aq) + H_2(g)
2. Water
3. Hydrogen formed is oxidized to water.
No effect on blue litmus paper (1), methylbenzene non- polar thus doesn’t dissociate hydrogen chloride to hydrogen ions which turn blue litmus paper red.(1)
H₂SO_3(aq) + Dye → H₂SO_{4 (aq)} + Dye + [o] ✔1
(coloured) (coloureless)
HOCl_(aq) + Dye → HCl_(aq) + Dye + [o] ✔1
(coloured) (colourless)
1. It acts as an impurity in the ice hence lowering its melting point. ✔ ½
2. Salt accelerates the rate of rusting of the iron parts of the motor vehicles. ✔ ½
1. The rate of diffusion of a fixed mass of gas is inversely proportional to the square root of its density at constant temperate and pressure. ✔1
2. TNO2 = √ (MNO2/MBr2)
  TBr2
  30/TBr2 = √46/160
  30/TBr2= √0.2875
  30/TBr2 = 0.5362/1
  TBr2 = 30/0.5362
  = 55.9493 sec
  The smell of bromine wiill be detected 25.94933 seconds later
1. The reaction is exothermic ∴ heat produced maintains the reaction
2. Platinum
3. 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(l)
alternative A
Q =it
= 0.4 x 30 x 60
=720C
Pb²⁺_(aq) + 2e → Pb_(s) 1
2 x 96500C → 207
720C = → ?
mass of Pb = 720 x 207
2 x 96500
= 0.77g
Alternative B
Q = it
= 0.4 x 30 x 60
= 720 C
No. of farads = 7.46 x 10^-3
96500
= 7.46 x 10^-32F → 207g
7.46 x 10^-3 F → ?
Mass = (7.46 x 10¯³ x 207) = 0.77
2
1. SO42-
2. Ba2+(aq) + SO42-(aq) BaSO4(s) ✔1
3. Al(OH)4 (aq) -✔1
1. Fe
  7/56
  
  0.125
  0.125 O
  
  3/6
  
  0.1875
  0.125
2. 2 Fe₂O_3(s) + 3 C_(s) → 4 Fe_(s) + 3CO_2(g)✓
1. Zinc blende ✔ ½
  Calamine ✔ ½
2. 2ZnS(s) + 3O2(g) 2ZnO(s) + 2SO2(g) (any 1 x 1mk)
  (for Zinc blende)
  OR ZnCO3(s) ZnO(s) + CO2(g)
  (for calamine)
3. Galvanising iron
  Making brass (Alloy of Zinc and copper) (Any 2 x ½ mk)
  Used as a negative electrode in dry cells.
  (or outer casing of dry-cells)
1. An oxide which reacts with both acids and alkalis ✔1
2. ZnO, PbO, Al2O3 (any 2 x ½ mk)
1. Hydrated Iron (III) oxide
2. High temperatures✓¹
  Acidic conditions✓¹
  Salty conditions first two
PCl₃ – have simple molecular structure ✓½ and weak van der waal forces. ✓½
NaCl – has ionic bond ✓½ and giant ionic ✓½ structure ionic bonds are stronger than van-der-waal bond hence high melting point. ✓¹