KCSE CHEMISTRY QUESTIONS AND ANSWERS PER TOPIC
expected response
I, production of carbon dioxide or carbon is oxidized to its highest oxidation number/carbon dioxide cannot burn further or carbon dioxide cannot burn further or carbon monoxide can burn further
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expected response
Number of neutrons =1
Number of electrons=1
a) The chart below is an outline of part of the periodic table.
With the help of vertical and horizontal lines, indicate the direction of increasing metallic nature of the elements.
Which types of elements are represented in the shaded area? b) i) Element A is the same group of the periodic table as chlorine. Write the formula of the compound formed when A reacts with potassium metal. ii) What type of bonding exists in the compound formed in (b) (l) above? Give a reason for your answers. c) Starting with aqueous magnesium sulphate, describe how you would obtain a sample of magnesium oxide. d) Write two ionic equations to show that aluminum hydroxide is amphoteric
During purification of copper by electrolysis, 1.48g of copper were deposited when current was passed through aqueous copper(II) sulphate for 2 1/2 hours. Calculate (CU = 63.5, 1 Faraday = 96,500C).
answers
The graph below shows the behaviour of a fixed mass of a gas at constant temperature.
a) What is the relationship between the volume and the pressure of the gas?
b) 3 litres of oxygen gas at one atmosphere pressure were compressed to two atmospheres at constant temperature. Calculate the volume occupied by the oxygen gas When magnesium metal is burnt in air, it reacts with both oxygen and nitrogen gases giving a white ash. Write two equations for the reactions that take place. (2mks)
Explain why the reactivity of group (VII) elements decreases down the group
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a) State the observation made when excess pentane is reacted with bromine gas
b) Name the compound formed in (a) above.
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The set – up below was used to prepare hydrogen chloride a gas and react it with iron powder. Study it and answer the questions that follow.
At the end of the reaction, the iron powder turned into a light green solid.
a) Identity the light green solid. b) At the beginning of the experiment, the Ph of the solution in container L was about 14.. At the end, the pH was found to be 2. Explain
answers
An organic compound with the formula C4 H10 O reacts with potassium metal to give hydrogen gas and white solid
(a) Write the structural formula of the compound (b) To which homologous series does the compound belong? (c) Write the equation for the reaction between the compound and potassium metal
Brass is an alloy of zinc and copper. Give one use of brass
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Oleum (H2S2O7) is an intermediate product in the industrial manufacture of sulphuric acid
(a) How is oleum converted into sulphuric acid? (b) Give one use of sulphuric acid
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A few crystals of potassium permanganate were carefully placed into water in a beaker at one spot. The beaker was left undisturbed for two hours. State and explain the observation that was made.
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Nitrogen (II) oxide and nitrogen (IV) oxide are some of the gases released from car exhaust pipes. State how these gases affect the environment
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Yellow phosphorous reacts with chlorine gas to form a yellow liquid. The liquid fumes when exposed to air. Explain these observations
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An oxide of element F has the formula F2O5
(a) Determine the oxidation state of F (b) In which group of the periodic- table is element F
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(a) what is meant by heat of vaporization
(b) The boiling points of ethanol, propanol and butanol are 780C, 97.20C and 1170C. explain this trend
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