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Explain in brief the cause of shoots of the plant bending towards light.
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Write balanced equation for the reaction between magnesium and hydrochloric acid. Name the product obtained and also identify the type of reaction.
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A DC motor is rotating in clockwise direction. How can the direction of rotation be reversed?
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A student added dilute HCl to Zn granules taken in a test tube. Identify the correct observation.
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A young green plant receives sunlight from one direction only. What will happen to its shoots and roots?
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Due to injury, flow of blood from vessels reduces the efficiency of pumping system. How is the leakage prevented?
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Why is the zig-zag copper tube painted black in a solar water heater?
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Show how would you connect three resistors, each of resistance
, so that the combination has a resistance of
(a)
(b)
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Several electric bulbs designed to be used on a 220 V electric supply line are rated 10 W. How many lamps can be connected in parallel with each other across the two wires of 220 V line if the maximum allowed current is 5 A?
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A current-carrying straight conductor is placed in the East-West direction. What will be the direction of the force experienced by this conductor due to the earth's magnetic field? How will this force get affected on
(a) reversing the direction of flow of current?
(b) doubling the magnitude of current?
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Under what conditions permanent electromagnet is obtained if a current-carrying solenoid is used? Support your answer with the help of a labelled circuit diagram.
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Crystals of copper sulphate are heated in a test tube for sometime.
(a) What is the colour of copper sulphate crystals
(i) before heating and
(ii) after heating?
(b) What is the source of liquid droplets seen on the inner upperside of the test tube during the heating process?
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A compound X of sodium is commonly used in the kitchen for making crispy pakoras. It is also used for curing acidity in the stomach. Identify X. Write its chemical formulae. State the reaction which takes place when it is heated during cooking.
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An ore on heating in air produces sulphur dioxide. Which process would you suggest for its concentration? Describe briefly any two steps involved in the conversion of this concentrated ore in the related metal.
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Write the balanced chemical equations for the following reactions
(a) Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations gives sodium chloride and sodium hydrogen carbonate.
(b) Sodium hydrogen carbonate on reaction with hydrochloric acid gives sodium chloride, water and liberates carbon dioxide.
(c) Copper sulphate on treatment with potassium iodide precipitates cuprous iodide
, liberates iodine gas and also forms potassium sulphate.
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In the given diagram, it shows the milliammeter reading in the circuit.
Write the value of current in the circuit.
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What is the right procedure to remove chlorophyll from a destarched leaf?
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In the experimental set up to show that carbon dioxide (CO2) is given out during respiration, why potassium hydroxide (KOH) is kept in the small test tube inside the flask?
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In an experiment on studying the dependence of the current (I) flowing through a given resistor, on the potential difference (V) applied across it, a student is to change the value of the current. While doing so, what can he change?
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The following circuit diagram shows the experimental set up for the study of dependence of current on potential difference. Which two circuit components are connected in series?
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To prepare a good temporary mount of the petunia leaf peel showing many stomata, from which part the student should take the peel?
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The solar cooker is painted black from inside. Why?
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A green layer is gradually formed on a copper plate left exposed to air for a week in a bathroom. What could this green substance be?
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Four students measured the pH values of water, lemon juice and sodium bicarbonate solution. Write the correct sequence of solutions in decreasing order of pH value.
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Suggest two ways to check the rancidity of food articles.
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You are provided with samples of bitter and sour food extracts. How can you test the presence of acids and bases among these solutions without tasting them?
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(a) Give an example of a combination reaction which is also exothermic reaction.
(b) Complete the following chemical reaction and balance it.
(c) Which two gases are evolved on heating ferrous sulphate?
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(a) Justify that brain is a highly protected organ.
(b) Which part of the brain controls all the voluntary actions and the involuntary action of the body?
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Write any three functions of the nervous system.
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Sujeet was making an electric bell. For that he was looking for an appropriate material. Sumit suggested him to use soft iron for this purpose and helped him in making electromagnet.
(a) What values are associated with Sumit?
(b) Why Sumit suggested for soft iron?
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(a) A current of 1 A flows in a series circuit containing an electric lamp and a conductor of
when connected to a 10 V battery. Calculate the resistance of the electric lamp.
(b) Now if a resistance of
is connected in parallel with this series combination, what change (if any) in current flowing through
conductor and potential difference across the lamp will take place? Give reason.
Or
Three bulbs each having power P are connected in series in an electric circuit. In another circuit, another set of three bulbs of same power are connected in parallel to the same source.
(a) Will the bulbs in both the circuits glow with the same brightness? Justify your answer.
(b) Now let one bulb in each circuit get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.
(c) Representing each bulb by a resistor, draw circuit diagram for each case.
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Draw a labelled diagram of an electric motor. Explain its principle and working. What is the function of split rings in an electric motor?
Or
A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is (i) pushed into the coil withdrawn from inside the coil (iii) held stationary inside the coil?
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(a) Draw a diagram of an excretory unit of human kidney and label the following
Bowman's capsule, glomerulus, collecting duct and renal artery.
(b) Write the important function of structural and functional unit of kidney.
(c) Write any one function of an artificial kidney.
Or
(a) Draw a schematic representation of transport and exchange of oxygen and carbon dioxide during transportation of blood in human beings and label on it.
Lung capillaries; Pulmonary artery to lungs Aorta to body; Pulmonary veins from lungs.
(b) What is the advantage of separate channels in mammals and birds for oxygenated and deoxygenated blood?
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A metal nitrate A on heating gives yellowish brown coloured metal oxide alongwith brown gas B and a colourless gas C. Aqueous solution of A on reaction with potassium iodide forms a yellow precipitate of compound D. Identify A, B, C, D. Also identify the types of both the reactions. Metal present in A is used in alloy which is used for soldering purposes.
Or
(a) Identify the acid and the base whose combination forms the common salt that you use in your food. Write its formula and chemical name of this salt. Name the source from where it is obtained.
(b) What is rock salt? Mention its colour and the reason due to which it has this colour.
(c) What happens when electricity is passed through brine? Write the chemical equation for it.
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A sulphate salt of group 2 element of the Periodic Table is a white, soft substance, which can be moulded into different shapes by making its dough. When this compound is left in open for sometimes, it becomes a solid mass and cannot be used for moulding purposes. Identify the sulphate salt. Why does it show such behaviour? Give the reaction involved.
Or
(a) What is meant by metallurgy?
(b) State two steps associated with extraction of copper from its ore.
(c) How is impure copper purified by electrolytic refining? Draw a labeled diagram to illustrate it.
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Draw the labelled diagram of dome type bio-gas plant and explain its construction and working.
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Energy from various sources is considered to have been derived from the sun. Do you agree? Justify your answer.
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