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1. (a) What is ‘environmental pollution? (b) Distinguish between biodegradable and non-biodegradable pollutants. (c) Choose the biodegradable pollutants from the list given below: Sewage, DDT, radioactive waste, agricultural waste. (3 Marks) 2. Why is ozone layer getting depleted at the higher levels of the atmosphere? (1Marks) 3. Name any two abiotic components of an environment. (1Marks) 4. Why green plants are called ‘producers’? (1Marks) 5. Explain ‘biological magnification’ with the help of an example. (2 Marks) 6. Define ‘trophic level’ (1 Marks) 7. What is the role of decomposers in the ecosystem? (1Marks) 8. State Ohm’s law. Write the necessary conditions for its validity. How is this law verified experimentally? What will be the nature of graph between potential difference and current for a conductor? Name the physical quantity that can be obtained from this graph. (5 Marks) 9. The charge possessed by an electron is 1.6 X 10 -19 coulombs. Find the number of electrons t...

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  1. 2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc metal taken in a test tube. When the contents are warmed, a gas evolves which is bubbled through a soap solution before testing. Write the equation of the chemical reaction involved and the test to detect the gas. Name the gas which will be evolved when the same metal reacts with dilute solution of a strong acid. (3 Marks) 2. Write one main difference between asexual and sexual mode of reproduction. Which species is likely to have comparatively better chances of survival – the one reproducing asexually or the one reproducing sexually ? Give reason to justify your answer. ( 3 Marks) 3. Show how would you join three resistors, each of resistance 9 W   so that the equivalent resistance of   of the combination is (i) 13.5 W   and (ii) 6 W (3 Marks) 4. (a) Write Joule’s law of heating.     (b) Two lamps, one rated 100 W; 220 V, and the other 60 W; 220 V, are connected in...

  1. Find the 9th term from the end   of the A.P. 5, 9, 13, ....., 185. (1 Marks) 2. Find the ratio in which y-axis divides the line segment joining the points A(5, - 6) and B( -1, -4).   Also find the coordinates of the point of division. (2 Marks) 3. How many terms of the A.P. 18, 16, 14, .... be taken so that their sum is zero? ( 2 Marks) 4. A decorative block, made up of two solids – a cube and a hemisphere. The base of the block is a cube of side 6 cm and the hemisphere fixed on the top has a diameter of 3.5 cm. Find the total surface area of the block. (3 Marks) 5. Find the distance of a point P(x, y) from the origin. ( 1 Marks) 6. Find volume of cone of hight 7 cm and radius 4 cm. (1 Marks) 7. In 4tan A = 3 Evaluate (4sinA – Cos A + 1) / (4sinA +Cos A - 1)                  (3Marks) 8. Prove that (sin A – 2 sin 3 A)/ (2cos 3 A – cos A) = tan A       ...

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  1. Write S.I. unit of resistivity. ( 1 Marks) 2. Study the following electric circuit of 3 Volt battery and find (i) the current flowing in the circuit and (ii) the potential difference across 10 Ω resistor. ( 3 Marks) 3. Find the current drawn from the battery by the network of four resistors Shown in the figure ( 3 Marks)   4. (a) Write two points of difference between electric energy and electric power. (b) Out of 60 W and 40 W lamps, which one has higher electrical resistance when in use? (c) What is the commercial unit of electric energy? Convert it into joules. ( 5 Marks) 5. Define 1 volt. Express it in terms of SI unit of work and charge calculate the amount of energy consumed in carrying a charge of 1 coulomb through a battery of 3 V. (3 Marks) 6. An electric bulb of resistance 200Ω draws a current of 1 Ampere. Calculate the power of the bulb the potential difference at its ends and the energy in kWh consumed ...

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