SECTION-A
1 Define reflex action.
2 The power rating of an appliance is 100W - 250V. What does it indicate?
3 Write the name of the substance whose vapours are used to run the turbine of the generator of ocean thermal energy plant ?
4 The pH of soil A is 7.5 while that of soil B is 4.5. Which of the two soils A or B should be treated with powdered chalk to adjust its pH and why ?
5 Define the term alloy. Give two advantages of making alloys.
6 (i) Name two organisms that obtain food through parasitic nutritive strategy.
(ii) How do fungi obtain their food ?
7 (a) A solution of a substance ‘X’ is used for testing carbon dioxide. Write the equation of the reaction of ‘X’ with carbon dioxide.
(b) How is ‘X’ obtained? Write chemical equation.
8 In water treatment plants, a white chemical substance having strong smell of chlorine gas is used to sterilise the water tank. Identify the chemical compound. Write its chemical name and formula. Also write the chemical equation for its preparation
9 (a) A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance whereas Z is a good conductor of electricity. Identify X, Y, Z.
(b) An element, X, on reaction with oxygen forms an oxide XO2. The oxide when dissolved in water turns blue litmus red. State whether element X a is metal or a non-metal.
(c) Name the metal which is alloyed with copper to make bronze.
10 Identify the type of chemical reactions in the following processes :
(i) Barium chloride solution is mixed with copper sulphate solution and a white precipitate is formed.
(ii) On heating copper powder in a china dish, the surface of copper powder becomes black.
(iii) On heating green ferrous sulphate crystals , reddish brown solid is left as residue and a gas having smell of burning sulphur is evolved.
(iv) Iron nails when left dipped in blue copper sulphate solution become brownish in colour and blue colour of copper sulphate solution fades away.
(v) Quicklime reacts vigourously with water releasing large amount of heat.
(vi) Silver nitrate solution reacts with sodium chloride solution and a white precipitate is formed.
11 Bile juice does not contain any enzyme but bile salts are important for digestion and absorption of fats. State reason.
12 Explain how do muscle cells change their shape ?
13 Mention the three kinds of cells present in blood. Write one function of each.
14 An electric bulb draws a current of 0.5 Ampere for 10 minutes. Calculate the amount of electric charge that flows through the circuit.
15 (a) A current carrying conductor is placed perpendicular in a magnetic field. Name the rule which can be used to find the direction of force acting on the conductor.
(b) State two ways to increase the force an a current carrying conductor in a magnetic field.
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