“We must trust to nothing but facts: These are presented to us by Nature, and cannot deceive. We ought, in every instance, to submit our reasoning to the test of experiment, and never to search for truth but by the natural road of experiment and observation.” ― Antoine Lavoisier, Elements of Chemistry


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Wednesday, 9 October 2013

singe displacement reaction worksheet

complete this reactions. then convert into word equations
1.Ag + KNO3 →      
2. Zn + AgNO3 →      
3. Cl2 + KI →      
4. Cu + FeSO4 →      
5. Fe + Pb(NO3)2 →      
6. Cu + Al2(SO4)3 →      
7. Al + Pb(NO3)2        
8. Cl2 + NaI →      
9. Fe + AgC2H3O2      
10. Al + CuCl2 →        
11. Br2 + CaI2 →        
12. Fe + CuSO4 →        
13. Cl2 + MgI2 →        

Monday, 7 October 2013

IGCSE Sound worksheet

IGCSE2  Sound Worksheet
11.  State true or false for each of the following statement
a.       Sound travels the fastest in solids and slowest in air.
b.      Sound can travel in vacuum
c.       The speed of sound is    3 x 108 m/s
d.      The speed of sound is a constant.
e.      Sound can travel from the Sun to the Earth.
f.        Pitch means how loud a sound is.
22.  What is the meaning of compression and rarefaction in term of vibration of sound waves?
33.  Delia ties a silver spoon to a piece of string and holds the ends to her ears.

When her friend Donny, strikes the spoon with a pencil, Delia hears a sound like a bell.
Explain the reason for this.

44. Explain why we do not hear explosions on the Sun, although they must be very loud.
55.   A musical instrument produces a sound wave with a frequency of 1000 Hz.  The sound wave  has a wavelength of 0.34 m in air.  Calculate the speed of the sound wave in air.

66.  In water the speed of sound is different.  The speed of a sound wave in water is 1300 m/s. The sound wave has a frequency of 1000Hz.  Calculate the wavelength of this sound wave.

77.  The diagram shows a ship using an Echo locator (SONAR) to find a shoal of fish.  The pulsed wave is transmitted from the ship, which is then reflected off the top of the shoal and is then picked up by the receiver.


A ship sending sound signals to the sea receives the echo 2 s later. If sound travels a t 1400 m/s in sea water, how deep is the sea?

88.  A student sits in the middle of a rectangular hall is 17 m wide, as shown in the diagram below. When student bangsna drum, two echos are heared, 0.05 s and 0.08 s respectively, after the bang.

 Assuming that there is no echo from the ceiling, calculate:
(i)      The speed os sound in the air
(ii)    The length of the hall