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The enthalpies of combustion of calcium, carbon and decomposition of calcium carbonate are indicated below;
(i) Draw an energy cycle diagram that links the enthalpy of formation of calcium carbonate to enthalpies of combustion of calcium, carbon and decomposition of calcium carbonate.
(ii) Determine the enthalpy of formation of calcium carbonate.
Date posted:
September 10, 2019
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Explain the difference in meaning between the following pairs of sentences.
a) (i) A Mr. Gitau came to see you when you were out.
(ii) Mr. Gitau came to see you when you were out.
b) (i) Lydia found the empty room.
(ii) Lydia found the room empty.
c) (i) She went and bought herself a skirt.
(ii) She went and bought a skirt herself.
d) (i) The guests who have badges will park at the yard.
(ii) The guests, who have badges, will park at the yard.
e) (i) Mary even learnt how to write.
(ii) Even Mary learnt how to write.
f) (i) The book which got lost is mine.
(ii) The book, which got lost, is mine.
g) (i) Harry, our elder brother, has arrived.
(ii) Harry, our elder brother has arrived.
h) (i) My uncle stopped to drink.
(ii) My uncle stopped drinking.
i) (i) Peter was executed like a murderer.
(ii) Peter was executed as a murderer.
j) (i) The injured student did not die happily.
(ii) The injured student did not die, happily.
k) i) I only heard the news briefly.
ii) I only heard the news in brief
l) (i) Mutunga has ten-day-old puppies in his kennel.
(ii) Mutunga has ten day-old puppies in his kennel.
Date posted:
September 10, 2019
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Factorise xy – zy – xw + zw hence simplify the expression completely.
Date posted:
September 10, 2019
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State two factors that affect the efficiency of a pulley system.
Date posted:
September 10, 2019
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The handle of the screw-jack in the figure below is 42cm long and the pitch of the screw is 0.5cm.
(i) Calculate the V.R of the screw jack.
(ii) Calculate the effort needed to lift the load of 1188N.
Date posted:
September 10, 2019
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An aqueous solution of zinc sulphate is electrolysed using platinum electrodes as shown in the set up below.
(a) (i) Write a half equation for the reaction taking place at electrode A.
(ii) Identify electrodes A and B
(iii) State and explain the observation at electrode B if copper plate was used instead of platinum electrode.
Date posted:
September 10, 2019
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A tourist visited Kenya with 2500 U.S dollars and changed the U.S dollars into Kenya Shillings at a local bank in Kenya when the exchange rates at the time were as follows:
(a) How much did he get in Kenya shillings?
(b) While in Kenya, he used Shs. 80,000 and after his stay he converted the remaining amount into sterling pounds. Calculate, to 2 decimal places, the Sterling Pounds that he got.
Date posted:
September 10, 2019
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A trolley of mass 5kg travelling to the right at 2m/s collides head on with another trolley of mass 3kg travelling at 4m/s to the left. Find their velocity after collision if the collision is perfectly inelastic.
Date posted:
September 9, 2019
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When a mass of 2kg is hang from a single spring, the spring extends by a distance x = 5cm. Determine the total extension in the set up below given that the springs are identical and weightless.
Date posted:
September 9, 2019
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A uniform metre rule is supported by force of 3N and 2N as shown in the figure below.Determine the weight of the half metre rule.
Date posted:
September 9, 2019
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Two candles A and B of equal lengths and thickness are joined together and balanced horizontally as shown below. Candle A is lit.State and explain what happens after a short time.
Date posted:
September 9, 2019
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The figure below shows a burette that was initially filled to 12ml with a liquid of density 0.8g/cm³.The liquid is allowed to run out for some time. If the volume of liquid removed from the burette has a mass of 14g,determine the final reading on the burette.
Date posted:
September 9, 2019
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The figure below shows a system of capacitors connected to 100V supply.
(i) the value of a capacitor for the whole circuit system.
(ii) the charge through the 6µF capacitor.
(iii) the p.d across of the 8µF capacitor.
Date posted:
September 9, 2019
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The two free ends of a coil are connected to a center – zero galvanometer. When the north pole of magnet is moved towards the coil, the pointer deflects in the direction shown in the figure below.
State with a reason the behaviour of the pointer inn the following cases:
(i) The north pole of the magnet is held stationary near P.
(ii) The north pole of the magnet is made to approach the coil from end Q
Date posted:
September 9, 2019
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200g of ice at 00C is added to 400g water in a well lagged calorimeter of mass 40g. The initial temperature of the water was 400C. If the final temperature of the mixture is X0C, (Specific latent of fusion of ice L = 3.36 x 105JK/g, specific heat capacity of water, c = 4200J/kg/K, specific heat capacity of copper = 400J/kg/K)
(i) Derive an expression for the amount of heat gained by ice to melt it and raise its temperature to X0C
(ii) Derive an expression for the amount of heat lost by the calorimeter and its content when their temperature falls to X0C.
(iii) Determine the value of X.
Date posted:
September 9, 2019
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Given the following. A filter funnel, a thermometer, a stop watch, ice at 00C, an immersion heater rated P watts, a beaker, a stand, boss and clamp and weighing machine.Describe an experiment to determine the specific latent heat of fusion of ice. Clearly state the measurements to be made.
Date posted:
September 9, 2019
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The figure below shows dots which were made by a ticker timer – tape attached to a trolley. The trolley was moving in the direction shown.
If the frequency used was 60Hz, distance AB = 12cm and BC = 7.2cm, determine
(i) The velocities between AB and BC
(ii) The acceleration of the trolley.
(b) An object is projected horizontally with a velocity of 40m/s at the top of a cliff 100m from the ground. (Take g = 10m/s2)
(i) Calculate the time taken for the object to hit the ground.
(ii) What is the range of the object from the foot of the cliff
Date posted:
September 9, 2019
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The grid below shows part of the periodic table. Use it to answer the questions that follow. The letters do not represent actual symbols.
(a) Which of the elements has the highest atomic radius? Explain.
(b) Identify the most reactive Oxidizing agent. Explain.
(c) Compare the atomic radius of P and R. Explain
(d) Give the formula of one stable ion with an electron arrangement of 2.8 which is:
(i) A Negatively charged divalent ion.
(ii) A Positively charged monovalent.
(e) Given that the mass number of W is 40. Write down the composition of its nucleus
(f) Write the formula of the compounds formed between.
(i) Element R and X.
(ii) Give one property of the structure formed when R and X bond.
Date posted:
September 9, 2019
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Sketch a block and tackle pulley with three movable pulleys in the lower block and two fixed pulleys in the upper block,to give a velocity ratio of 6.
Find:
(i) An effort of 450N is used to raise a load of 2700N. Determine:
- Mechanical advantage (M.A)
- Efficiency of the pulley system.
(ii) If all the wasted energy is used to raise the lower block and the frictional force between pulleys and moving parts is 3.6N; determine the weight of the lower block.
(iii) If the load moved through a distance of 50cm, determine the useful work done by the effort.
Date posted:
September 9, 2019
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Study the following part of the solvay process for the manufacture of sodium carbonate and answer the questions that follow:
(i) State the main source of Carbon (IV) oxide in the process.
(ii) Write down the overall equation for the reaction in chamber I.
(iii) Name process in step 1.
Date posted:
September 9, 2019
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The spiral springs shown in the figure below are identical. Each spring has a spring constant K = 200 N/m. Each rod weighs 0.1 N and each spring weigh 0.1 N. Determine the total extension caused by the 150 N weight.
Date posted:
September 9, 2019
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A balloon with argon gas of volume 199cm3 at the earth‘s surface where the temperature is 210C, and the pressure 760mm of mercury. If it is allowed to ascend to a height where the temperature is 20C and the pressure 100mm of mercury, calculate the volume of the balloon.
Date posted:
September 9, 2019
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In a faulty mercury-in-glass thermometer it was found that the mercury level stands at 2 cm mark in the tube at 00C and 20cm when in steam above boiling point of water at normal atmospheric pressure. Calculate the temperature when the mercury stands at 13cm mark.
Date posted:
September 9, 2019
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A micrometer screw gauge which had an error of +0.02mm was used to measure the diameter of a spherical marble. If the actual diameter was 3.67mm, draw a micrometer screw gauge showing its reading.
Date posted:
September 9, 2019
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In an experiment to determine the focal length of a converging lens several values of image distance and the corresponding magnification were obtained. A graph of magnification m against image distance (V) was plotted as shown below.
From the graph determine the focal length of the converging lens.
Date posted:
September 9, 2019
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The figure below represents a pinhole camera.Sketch rays to show the formation of an enlarged image in the camera. Label both the image and the object.
Date posted:
September 9, 2019
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Gas Q with a relative molecular mass of 48 took 50 seconds to diffuse through a porous diaphragm. How long will it take for the same amount of hydrogen Chloride (HCl) to diffuse through the same diaphragm under similar conditions? (H = 1.0, Cl = 35.5).
Date posted:
September 9, 2019
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Draw a well labeled diagram showing how blister copper is purified.
Date posted:
September 9, 2019
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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 1O0C. (SHC = 4.2-1g K-1, density = 1.0g/cm3, H = 1.0, O = 16.0)
Date posted:
September 9, 2019
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The figure below shows a bar magnet. Point A and B are in front of the magnet.
On the axis provided, sketch a graph showing how the magnetic field strength changes from A to B.
Date posted:
September 9, 2019