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An oil drop of volume V m3 introduced on the surface of water spreads to form patch whose area is Am2. Derive an expression for obtaining the diameter, d of a molecule of oil.
Date posted:
February 7, 2017
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In an experiment to estimate the diameter of an oil molecule, an oil drop of diameter 0.05 cm spreads over a circular patch whose diameter is 20 cm.
Determine i) the volume of the oil drop
ii) The area of the patch covered by the oil
iii) The diameter of the oil molecule
Date posted:
February 7, 2017
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State the assumption made when calculating the size of a molecule in the oil drop experiment
Date posted:
February 7, 2017
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An un-magnetized steel rod is clamped facing North-South direction and then hammered repeatedly for some time. When tested, it is found to be magnetized. Explain this observation
Date posted:
February 7, 2017
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Distinguish between soft and hard magnetic materials
Date posted:
February 7, 2017
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Given a bar magnet, an iron bar and a string
i) Describe a simple experiment to distinguish between the magnet and the iron bar
(ii) State with reasons the observations that would be made in the experiment.
Date posted:
February 7, 2017
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Give reason why attraction in magnetism is not regarded as reliable method of testing for polarity
Date posted:
February 7, 2017
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State the reason for topping up a lead-acid accumulator with distilled water.
Date posted:
February 7, 2017
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State one advantage of a lead-acid accumulator over a nickel-iron(NiFe) accumulator.
Date posted:
February 7, 2017
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A car battery requires topping up with distilled water occasionally. Explain why this is necessary and why distilled water is used
Date posted:
February 7, 2017
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State two advantages of an alkaline battery over a lead acid battery.
Date posted:
February 7, 2017
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State two uses of a charged gold leaf electroscope.
Date posted:
February 7, 2017
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A positively charged sphere is suspended by an insulating thread. A negatively charged conductor is suspended near it. The conductor is first attracted, after touching the sphere it is repelled. Explain this observation
Date posted:
February 7, 2017
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A conductor is slowly brought near the cap of a positively charged electroscope. The leaf first collapses and then diverges. State the charge on the conductor
Date posted:
February 7, 2017
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A positively charged rod is brought near the cap of a leaf electroscope. The cap is the earthed momentarily by touching with the finger. Finally the rod is withdrawn. The electroscope is found to be negatively charged. Explain how this charge is acquired.
Date posted:
February 7, 2017
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A highly negatively charged rod is gradually brought close to the cap of a positively charged electroscope. It is observed that the leaf collapses initially and then diverges. Explain the observation.
Date posted:
February 7, 2017
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In certain pinhole camera, the screen is 10cm from the pinhole. When the camera is placed 6 m away from a tree, a sharp image of the tree 16 cm high is formed on the screen. Determine the height of the tree
Date posted:
February 7, 2017
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In a vacuum flask the walls enclosing the vacuum are silvered on the inside. State the reason for this
Date posted:
February 6, 2017
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A wooden bench and a metal bench are both left in the sun for a long time. Explain why the metal bench feels hotter to touch.
Date posted:
February 6, 2017
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State two variables that must be controlled in an experiment for comparing the thermal conductivities of different metal rods of the same diameter.
Date posted:
February 6, 2017
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When a liquid is heated in a glass flask, its level at first falls then rises. Explain this observation.
Date posted:
February 6, 2017
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Clinical thermometer has a constriction in the bore just above the bulb. State the use of this constriction.
Date posted:
February 6, 2017
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Explain why a glass container with thick walls is more likely to crack than one with a thin wall when a very hot liquid is poured into it.
Date posted:
February 6, 2017
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Give a reason why a concrete beam reinforced with steel does not crack when subjected to changes in temperature.
Date posted:
February 6, 2017
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State why it is easier to separate water into drops than to separate a solid into smaller pieces
Date posted:
February 6, 2017
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Two identical beakers A and B containing equal volumes of water are placed on a bench. The water in A is cold while in B it is warm. Identical pieces of potassium permanganate are placed gently at the bottom of each beaker inside the water. It is observed that the spread of colour in B is faster than in A. Explain this observation
Date posted:
February 6, 2017
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Distinguish between solid and liquid states of matter in terms of intermolecular forces.
Date posted:
February 6, 2017
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Two identical tubes A and B held horizontally contain air and water respectively. A small quantity of coloured gas is introduced at one end of A while a small quantity of coloured water is introduced at one end of B. State with reason the tube in which the colour will reach the other end faster.
Date posted:
February 6, 2017
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Explain the cause of random motion of smoke particles as observed in Brownian motion experiment using a smoke cell.
Date posted:
February 6, 2017
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A student wearing sharp pointed heeled shoes is likely to damage a soft wooden floor. Explain
Date posted:
February 6, 2017