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MADHUSTHALI VIDYAPEETH F.M 50 Time Date : PRE-BOARD- I : 2019-2020 SUBJECT: PHYSICS CLASS- X Question 1 [3+2+3+2=10] a) Calculate the mass of ice required to lower the temperature of 300g of water at 40 to water at 0 . (Specific latent heat of ice = 336Jg-1, Specific heat capacity of water = 4.2Jg-1 -1) b) What do you understand by the following statements: i) The heat capacity of a body is 60JK-1. ii) The specific heat capacity of lead is 130Jkg-1K-1. c) A solid of mass 50g at 150 is placed in 100g of water at 11 , when the final temperature recorded is 20 . Find the specific heat capacity of the solid. (S.H.C. of water = 4.2Jg-1 -1). d) i)A certain mass of ice at 0 is converted to steam at 100 by constant heating. Draw the temperature-time graph showing the change in phases. ii) You have a choice of three metals A, B, C of S.H.C. 900 Jkg-1 -1, 380Jkg-1 -1, 460Jkg-1 -1 respectively, to make a calorimeter. Which material will you select? Question 2 [2+2+2+4=10] a) i) Name the colour code of the wire which is connected to the metallic body of an appliance. ii) To which wire of a cable in a power circuit should the metal case of a geyser be connected? iii) To which wire should the fuse be connected? iv) Which particles are responsible for current in conductor? b) Define specific resistance and state its SI unit. c) An electric bulb of resistance 500 , draws a current of 0.4A. Calculate the power of the bulb and the potential difference at its ends. d) A battery of emf 12V and internal resistance 2 is connected with two resistors A and B of resistance 4 and 6 respectively joined in series. Find: i) current in the circuit ii) terminal voltage of the battery iii) potential difference across 6 resistor. iv) electrical energy spent per minute in 4 resistor Question 3 [2x5=10] a) An element decays to 223 85 after emitting 2 -particles and 1 -particle. Find the atomic mass and atomic number of S. b) A radioactive substance is oxidized. Will there be any change in nature of its radioactivity? c) When does the nucleus of an atom tends to be radioactive? d) State two differences between the nuclear fission and nuclear fusion. e)i) Represent the change in the nucleus of a radioactive element when a -particle is emitted. ii) What is the name given to the elements with same mass number and different atomic number? Question 4 [2+2+4+2=10] a) Which coil of a step-up transformer is made of thicker wire and why? b) What energy change takes place in a d.c. motor? On what principle does it work? State one factor to increase its speed of rotation. c) Name the device you will use to obtain 11V a.c. from 220V a.c. Draw a labeled diagram of the device. Name a type of loss of energy in it and state how is it remedied. d) A magnet kept at the centre of two coils A and B is moved to and fro as shown in the diagram. The two galvanometers show deflection. State with reason whether: (x>y) or (y>x) [ x and y are magnitudes of deflection] Question 5 a) How does uniform circular motion differs from uniform linear motion? b) State two differences between centripetal force and centrifugal force. c)From the diagram given alongside, find: [2x5=10] i) value of w ii) resultant moment and its direction if weight w is moved to 3cm mark. iii) position of another weight of 50gf to balance the rule in part(ii). d) A uniform half-metre rule balances on a knife edge at 29cm mark, when a weight of 20gf is suspended from one end. i)Draw a diagram for the arrangement. ii) What is the weight of the half-metre rule?
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