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AB is current-carrying conductor in the plane of the paper as shown in figure. What are the directions of magnetic fields produced by it at the points P and O? If r1 > r2, where will the strength of the magnetic field be larger?
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Identify the compound X on the basis of the reactions given below. Also, write the name and chemical formulae of A, B and C.
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With labelled diagrams describe an activity to find out the conditions under which iron rusts.
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(a) How is the direction of electric current related to the direction of flow of electrons in a wire?
(b) Calculate the current in a circuit if 500 C of charge passes through it in 10 minutes.
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How electric potential is generated in a conductor during the flowing charges?
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(a) What do you mean by olfactory indicators?
(b) Zinc is an amphoteric metal. Justify with reaction.
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How will the magnetic field produced at a point due to a current-carrying circular coil change if we
(a) increase the current flowing through the coil?
(b) reverse the direction of current through the coil?
(c) increase the number of turns in the coil?
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Identify the reducing agent in the following reactions
(a)
(b)
(c)
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Two lamps, one rated 60 W at 220 V and the other 40 W at 220 V, are connected in parallel to the electric supply at 220 V
(a) Draw a circuit diagram to show the connections.
(b) Calculate the current drawn from the electric supply.
(c) Calculate the total energy consumed by the two lamps together when they operate for one hour.
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A gas is produced in the laboratory is highly soluble in water. Its colourless solution turns pink when a few drops of phenolphthalein is added to it. What is the nature of this gas?
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Which is the internal energy reserve in plants? Do the animals have the same energy reserve?
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Name two hormones secreted by pancreas. Write one function of each hormone.
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Name the
products formed on strongly heating ferrous sulphate crystals. What type of
chemical reaction occurs in this change?
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Identify the parts labelled X, Y and Z in the given circuit.
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How is the supply of electricity maintained by a windmill when there is no wind and by a solar panel when there is no sun?
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Four identical cells of emf 1.5 V each were connected. The potential difference between the two points A and B would be equal to 6.0 V. Draw the circuit.
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Plant respiration is slower than animal respiration. Suggest one reason for it.
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The best photosynthetic lights are red and blue. Why?
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A voltmeter has a least count of 0.05 V While doing Ohm's law experiment, a student observed that the pointer of the voltmeter coincides with 15th division. Find the correct reading.
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Why can Zn displace hydrogen from dil. HCl?
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When do guard cells swell?
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Suggest two salts that are used in black and white photography.
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Identify the procedure used in the working of an artificial kidney.
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On putting a few drops of a liquid on a pH strip, the colour of the pH strip changed to red. Identify the compound.
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What happens chemically when quick lime is added to water?
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Would you consider hydrogen to be a cleaner and more efficient fuel than CNG?
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Name the products formed in each of the following cases
(a) Hydrochloric acid reacts with caustic soda.
(b) Granulated zinc reacts with caustic soda.
(c) Carbon dioxide is passed into lime water.
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(a) What happens at the synapse between two neurons?
(b) What is the function of receptors in our body?
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Mention the functions of
(a) Thyroxine
(b) Calcitonin and
(c) Testosterone.
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Laxmi and her mother went to the market to purchase some household articles. Laxmi's mother was going to purchase 100 W electric bulb. Laxmi advised her to purchase CFL.
She told her mother that it will consume less amount of power and will save electricity.
(a) What qualities do you notice in Laxmi?
(b) A 100 W bulb and a 500 W bulb are joined in parallel to the mains. Which bulb will draw more current?
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(a) Name an instrument that measures electric current in a circuit. Define the unit of electric current.
(b) What do the following symbols mean in circuit diagrams?
(c) An electric circuit consisting of a 0.5 m long nichrome wire XY, an ammeter, a voltmeter, four cells of 1.5 V each and a plug key was set up.
(c) Draw a diagram of the electric circuit to study the relation between the potential difference maintained between the points X and Y and the electric current flowing through XY.
(ii) Following graph was plotted between V and l values
What would be the values of
ratios when the potential difference is 0.8 V 1.2 V and 1.6 V respectively?
What conclusion do you draw from these values?
Or
In a household electric circuit, different applianes are connected to parallel to one another. Give two reasons. An electrician puts a fuse of rating 5 A in that part of domestic electrical circuit in which an electrical heater of rating 1.5 kW, 220 V is operating. What is likely to happen in this case and why? What changes, if any, needs to be made?
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Explain the underlying principle and working of an electric generator by drawing a labelled diagram. What is the function of brushes?
Or
How does a solenoid behave like a magnet?
Can you determine the North and South poles of a current-carrying solenoid with the help of a bar magnet. Explain.
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Sketch a schematic flow chart showing the breakdown of glucose in a cell to provide energy in the following conditions
(a) In the presence of oxygen.
(b) In the absence of oxygen.
(c) Where there is a lack of oxygen.
Or
(a) Draw a diagram to show the nutrition in Amoeba and label the parts used for this purpose. Mention any other purpose served by this part other than nutrition.
(b) Name the glands associated with digestion of starch in human digestive tract and mention their role.
(c) How is required pH maintained in the stomach and small intestine?
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(a) Why do fireflies glow at night?
(b) Identify the oxidising agent in the following reactions
(i)
(ii)
(iii)
Or
(a) Crystals of a substance changed their colour on heating in a closed test tube but regained it after sometime when they were allowed to cool down. Name the substance and write its formula and explain the phenomenon involved.
(b) Name the compound whose one formula unit is associated with 10 water molecules. How is it prepared? Give equations of related reactions. Give two uses of the compound.
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A non-metal P which is the largest constituent of air. When heated with H2 in 1 : 3 ratio in the presence of catalyst (Fe) gives a gas Q. On heating with O2, it gives an oxide R. If this oxide is passed into water in the presence of air, it gives an acid S which acts as a strong oxidising agent.
(a) Identify P, Q, R and S.
(b) To which group of Periodic Table does this non-metal belong?
Or
Give reasons for the following
(a) Silver and copper lose their shine when they are exposed to air. Name the substance formed on their surface in each case.
(b) Tarnished copper vessels are cleaned with tamarind juice.
(c) Aluminium is more reactive than iron yet there is less corrosion of aluminium as compared to iron when both are exposed to air.
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What are the
environmental consequences of the increasing demand for energy? What steps
would you suggest to reduce energy consumption?
Or
What is solar water
heater? With the help of a schematic diagram, describe the principle and
working of a solar water heater.
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