CHEMISTRY TOPICAL QUESTIONS AND ANSWERS

K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.20

7/10/2020

KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

Equal volumes of 1M monobasic acids L and M were each reacted with excess magnesium turnings. The table below shows the volumes of the gas produced after one minute.

Explain the differences in the volumes of the gas produced

ANSWERS

M is a strong acid while L is a weak acid.
M has many ions in solution that take part in a reaction forming more product that L with few ions in solution.

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.19

7/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

The scheme below shows the energy changes that are involved between ice, water and steam. Study it and answer the questions that follow

(a) What name is given to the energy change, ΔH4?
(b) What is the sign of ΔH3? Give a reason

ANSWERS

a)Molar heat of fusion
b)-∆H3 process to exothermic (heat given out to the surrounding)

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.17

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

(a) what condition is necessary for an equilibrium to be established?
(b) When calcium carbonate is heated, the equilibrium shown below is established
CaCO₃ (s) → CaO(s) + CO₂(g)
How would the position of equilibrium be affected if a small amount of dilute potassium hydroxide is added to the equilibrium mixture? Explain

ANSWERS

a) When the rate of forward reaction is equal to the rate of backward reaction.
b)The equilibrium shift to the right potassium hydroxide reacts with Carbon dioxide concentration of CO2

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.16

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

The table below gives some information about elements I,II,III and IV which are in the same group of the periodic table. Use the information to answer the questions that follows.

State and explain the relationship between the variations in the first ionization energies and the atomic radii.

ANSWERS

Increases atomic radius results in decrease of 1st ionization energy
Increasing the radius, decreases the force of attraction from to the outermost electron. Hence decreasing in the 1st ionization energy down the group.

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.15

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

In terms of structure and bonding, explain why graphite is used as a lubricant.

ANSWERS

Graphite structure is layered with layers together by weak vander waals force.
These forces are easily broken making layers to slide over each other hence good lubricant

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.14

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

100 g of a radioactive substance was reduced to 12.5 g in 15.6 years. Calculate the half – life of the substance

ANSWERS

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.13

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

Methane reacts with oxygen according to the equation given below.
CH₄ (g) + 2O₂ (g) →CO₂ (g) + 2H₂O (l), ΔH = 890 KJ MOL^-1
Calculate the volume of methane which would produce 111.25 kj when completely burnt.(Molar volume of a gas = 24 litres.)

ANSWERS

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.12

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

In the industrial extraction of lead, the ore is first roasted in a furnace. The solid mixture obtained is then fed into another furnace together with coke, limestone and scarp iron. State the function of each of the following in this process:
(a) Coke
(b) Limestone
(c) Scrap iron

ANSWERS

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.11

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

The reaction between how concentrated sodium hydroxide and chlorine produces sodium chlorate (V), sodium chloride and water
(a) Write the equation for the reaction
(b) Give one use of sodium chlorate (V)

ANSWERS

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.10

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

The sketch completely with substance H is converted into J. study it and answer the question that follows.

Why do the two curves become horizontal after sometime?

ANSWERS

The reaction has stopped as substance H has all been converted to J yet the time is continuing

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.9

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

A certain carbonate, GCO3, reacts with dilute hydrochloric acid according to the equation given below:
GCO₃(s) + 2HCL(aq)= GCl₂ (aq) + (CO₂(g) + H₂O(l)
If 1 g of the carbonate reacts completely with 20 cm³ of 1 M hydrochloric acid ,calculate the relative atomic mass of G (C = 12.0 = 16.0)

ANSWERS

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.8

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

Determine the oxidation state of sulphur in the following compounds:
a) H2S………………………
b) Na2S……………………

ANSWERS

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.7

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

Give the name and draw the structural formula of the compound formed when one mole of ethane reacts with one mole of chlorine gas.

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.6

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

Use the information in the table below to answer the questions that follow. (The letters do not represent the actual symbols of the elements)

a) Which two letters represent the same element? Give a reason.
b) Give the number of neutrons in an atom of element D

ANSWERS

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K.C.S.E Chemistry Q & A - MODEL 2005.PP1.QN.5

6/10/2020

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

Zinc oxide reacts with acids and alkalis
a) Write the equation for the reaction between zinc oxide and:
i) Dilute sulphuric acid
ii) Sodium hydroxide solution
b) What property of zinc oxide is shown by the reaction in (a) above?

ANSWERS

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

15

KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

12

KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

10

KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

9

KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

8

KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

7

KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

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KCSE Chemistry 2005 Topical Questions and Answers

All Questions Featuring Chemistry Form 1, Form 2, Form 3, Form 4, Paper 1, Paper 2 and Paper 3

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