2. Give reason why, a block of plastic when released under water comes up to the surface of water.
3. (a) Define relative density.(b) Relative density of silver in 10.8. The density of water is 103 kg/ m. What is the density of silver in SI unit?
4. State two main postulates of Thomson’s model of an atom.
5. (a)Calculate the number of molecules in 8 g of O2 (b)Calculate the number of moles is 52 gas of He (Helium) [At. mass: O = 16 u,He = 4 u]
6.(a) Define 1 watt.(b) An electric bulb of 60 W (sixty watt) is used for 6 (six) hours per day. Calculate the units of energy consumed in one day by the bulb. 
7. (a)What are polyatomic ions ? b) Write the formulae and names of the compounds formed by combination of (i)Fe3+ and SO4-2 (ii)NH41+ and Co3-2
8. Define valency of an element. Find the valency of chlorine and Magnesium (At. No. Of Chlorine= 17, Magnesium =12)
9. Explain how human ear works in the transmission of sound wave to the brain. 
10.(a)Define potential energy. Write an expression for potential energy of an object of mass m raised through a height h.(b) Find the energy possessed by an object of mass 10 kg when it is raised to a height of six meter above the ground given g = 9.8 m/s2.
11. Define frequency, amplitude and speed of a sound wave.
12. (a) State the drawbacks of Rutherford’s model of the atom ? Explain the suggestions put forward by Neils Bohr in his model of atom to overcome these drawbacks. (b) Define isotopes with one example. Write two applications of isotopes.
13.(a)Write the name of the sub - atomic particle discovered by J. Chadwick. What type of charge occurs on this particle? In which part of atom this particle is located? (b)List three steps of experiment performed by Rutherford for his model of an atom. (c)Define isobars, write its one example. (d)Which scientist concluded that size of nucleus is very small as compared to size of an atom ? 
(a) Write chemical formula of Potassium Sulphate.
(b)Calculate the molar mass of :
(i)Ethyne (C2H2) and
(ii)Phosphorous molecule (P4) (Atomic mass of C = 12u, H=1u and P =31u).
14. (a) State Law of conservation of energy. Explain it with one example.(b) Two girls each of weight 400 N (Four hundred N) climb up a rope through a height of 8 meters (eight meters). Girl A takes 20 (Twenty) seconds while Girl B takes Fifty seconds to accomplish this task. What is the power expended by each girl ?
(c)An electric heater is rated 1500 watt. How much energy does it uses in 10 hours (ten hours) ? 
15.(a)Define work done by a constant force on an object. Write an expression also for the work done.
(b)How much work will be done on an object by a force if the displacement of the object is zero ?
(c) What is the kinetic energy of an object? Write an expression for the kinetic energy of an object of mass m moving with a speed v.
OR, State law of conservation of energy. An object of mass 10kg is dropped from a height 5m above the ground. Show that total energy of the object at the height 5m and 2m is same. (Take g = 10m/s2). What happens to the energy when the object touches the ground?
16. In the wave motion of a string, every particle:-
(a)Rotates (b) Oscillates (c) is stationary (d) displaces from one end to another.
17. The wave produced in the interior of the earth is called:-
(a)Longitudinal (b) Seismic wave (c) Sound wave (d) Transverse wave
18. We can sense a compression is a slinky if :-
(a) Turns are close to each other (b) Neither turns are close nor far away
(c)Turns are far away (d) None of these.
19. Up thrust depends upon :- (a)volume (b)density (c)‘g’ (d)All of these
20. When all ice floating in water melts the level of water in Container:-
(a)Falls (b) Rises (c)remains unchanged (d) None of these
21.Mass of an object in air is 40 kg. Mass of this object in water will be :-
(a)More than 40 kg (b)Less than 40 kg (c)40 kg (d)Zero
22. Which of the following has the highest density?
(a)Alcohol (b) Glycerin (c) Water (d) Sea water
Science Class 9 Standard Question Papers 2012-13 -as per the latest Exam Syllabus
ix_science_sample_pape - SA-2-4