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A compound whose structure is shown below is found in a detergent. With reference to the structure, explain how the detergent removes grease during washing. (2mks) 
expected response
The ionic end lowers the surface tensions of water , facilitating mixing while the nonionic end (non-polar end) mixes with grease, dislodging it from the fabric. a) Using dots(.) and crosses (x) to represent electrons draw diagram to represent the bonding in: (i) NH3 (ii) NH4+ (1mk) b) State why an ammonia molecule (NH3) can combine with H+ to form NH4+ (Atomic numbers: N=7 and H=1) (1mk)
Expected Response
Ammonia can be converted to nitrogen monoxide as shown in the equation below 
(a) Explain how an increase in temperature would affect the yield of nitrogen monoxide (2mks) (b) On the energy level diagram above sketch, the energy level diagram that would be obtained if the reaction is carried out in the presence of platinum catalyst. (1 mk)
eXPECTED rESPONSE
In an experiment to study the diffusion of gases, a student set up the apparatus shown in diagram 1. After sometime the student noticed a change in the water level as shown in the diagram 
Give an explanation for the change in water level (2mks)
expected response
Air is less dense than carbon dioxide and so it enters the porous pot faster than carbon dioxide out of it. This sets up a higher pressure; in the pot and the level rises as shown:
Zinc metal and hydrochloric acid reacts according to the following equation Zn(s) + 2HCI (aq)→ ZnCI2 (aq) + H2 (g) 1.96 g of zinc were reacted with 100cm3of 0.2M hydrochloric acid (a) Determine the reagent that was in excess (b) Calculate the total volume of hydrogen gas was liberated S.T.P (Zn= 65.4 Molar gas volume = 22.4 litres at S.T.P)
expected response
A fixed mass of a gas has a volume of 250cm3 at a temperature of 270C and 750mm Hg pressure. Calculate the volume the gas would occupy at 420C (2mks)
expected response
(a) State what would happen when a few drops of dilute hydrochloric acid are added to the mixture at equilibrium
(b) Give a reason for your answer in (a) above
answer
(a) Solid dissolves
(b) addition of hydrochloric acid favour backward reaction
Describe how a solid sample of Zin (II) carbonate can be prepared starting with zinc oxide
ANSWER
The structures below represents a portion of a polymer
(a) Give the name of the polymer (b) Give one industrial use of the polymer
answer
With reference to iodine, distinguish between covalent bonds and Van Der Waals forces
answers
When carbon dioxide gas was passed through aqueous calcium hydroxide a white suspension was formed
(a) Write an equation for the reaction that took place (b) State and explain the changes that would occur when carbon dioxide gas is bubbled through the white suspension
answers
Iron is extracted from its ore by the blast furnace process
(a) Name one ore from which iron is extracted (b) One of the impurities in iron is removed in the form of calcium silicate. Write an equation for the reaction in which calcium silicate is produced
answers
Use the equations below to answer the questions that follow
answers
Concentrated nitric (V) acid was added to iron (II) sulphate acidified with sulphuric acid and the mixture heated. The solution turned from pale green to yellow with evolution of brown gas. Explain these observations.
answer
In an experiment, sulphur dioxide gas was bubbled into water followed by chlorine gas. The resulting clear solution gave a white precipitate when mixed with a acidified barium chloride solution. Explain these observations
ANSWER
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January 2025
AuthorMaurice Atika is a teacher and a netprenuer. |
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