Ozone Depletion and Its Effect

                                               Ozone
      Ozone is a light blue gas and has an unpleasant odour. In the troposphere, ozone causes breathing difficulties,asthma and eye irritation. Ozone is an allotropic form of oxygen comprising of three oxygen atoms,O3 ozone is an important gas in the stratosphere.
Explanation:-
      Most of UV radiation coming from sun are filtered or scrrened out by the ozone layer .Otherwise, sunlight wouid be much more hazardous for human beings, animals and plants.On absorbing UV radiation, ozone molecule breaks up to form a oxygen molecule and atomic oxygen.
         O3 → O2 + O
Atomic  oxygen  is very reactive. Atomic oxgen reacts readily with an oxygen molecule to form ozone, there by releasing  heat
    O2 + O →O3 + heat
The destruction anf reformation of ozone are powered by UV radiation.
Human activities disturb this natural balance and  stability  of ozone  layer.
scientists have discovered a reduction in the amount of ozone  in the stratosphere .
The region in which the amount of ozone has been reduced is called as ozone hole.
ozone hole was first discovered in October, 1980 over Antarctica.

GLOBAL WARMING

Definetion :-                                                    

The warming of the atmosphere whichvis due to our influence on the greenhouse effect is known as global warming.
Explanation :-
The increasing use of fossil fuels and the deforestation have led to an increase in the levels of CO2 in the air.Gases like water vspour,methane and CFCs also act in a similar way in the atmosphere. These gases are called green house gases.
The higher the concentration of green house gases in the air,the greater is the green house effect, and greater will be the increase in temperature.
Certain human activities are threatening to cause a significant increase in the greenhouse effect.
Global warming is due to an upset in the natural balance of the concentration of greenhouse gases in the atmosphere.
If global warming continues,then
●Temperature of the earth will gradually increase.
●Polar ice may melt and cause significant increase in sea levels.
●So the atmosphere becomes hotter.
●The earth climate may change,affecting both where there is rainfall and how much there is of it.This could cause both increased risk of flooding in some regions and drought in others.

Transformer

DEFINITION: -
                       A devise used to increase or decrease the A.C voltage.
PRINCIPLE :-
                      The device works on the principle of mutual induction.
CONSTRUCTION: -
                                 It consist if a soft iron core upon which  are waunded two separate layers of coils.
The coil into which current is sent is called primary coil and other secondary coil.on picture (1)
WORKING: -
                    When the A.C current, passes through the primary coil,the changing magnetic fueld lines also passes through the secondary coil and according to farady's law e.m.f is induced in the secondary coil.
If Np and Ns are the Number of turns in primary and secondary coil respectively, and Vp and Vs are the voltage across primary and secondary coil respectively, then the transformer equation is (on picture 2 )
   
      Vp/Vs = Np/Ns  or   Vs/Vp = Ns/ Np
If Vs >Vp ; then the transformer is called step up transformers.
If Vs < Vp ; then the transformer is called  step down transformer.

House Safety Alarm

Now you can catch the burglar:-
We can use single NAND gate to make burglar alarm. This can be done by using NAND gate (combination of NOT and AND gate ),an LDR (light depending resistor), a push button Switch S and an alarm on picture attached.
Cinnect LDR between NAND gate input B and rhe positive terminal of the battery.
The LDR will cause a High level input '1' at B when in light because of its Low resistance. The LDR will cause a low level input '0' at B when light is interrupted and cause high resistance in LDR .
A low level signal is also caused at A when burglar steps on switch S.
si this burglar alarm sound when either burglar interrupts light falling on LDR or steps on switch  S.

CATHODE RAYS OSCILLOSCOPE (C.R.O)

Definition : -
                                   A device used to measure and compare time period, magnitude and amplitude.
Construction: -
(1) Electron gun:- To produce beam of electron
(2) Grid :- To control brightness               

(3) Deflecting System: - To make beam straight by (x,y) plates
(4) Screen :-A flourosent screen made of phosphorus
       
                        

LAW OF MASS ACTION

                     
INTRODUCTION :-
                                  Two chemist C.M GULDBERG and P.WAAGE in 1864 proposed the law of mass action to describe the equilibrium state.

DEFINITION  :-
                            It states that the rate at which a substance react is directly proportional to its active mass, and the rate at which the reaction proceed is directly proportional to its active masses of the reactants.

DERIVATION :-
                                  Consider a hypothetical reaction in which (a) moles of reactant A and (b) moles of reactant B react to give (c) moles of product C and (d) moles of product D at equilibrium.
                                             aA+bB     ←→ cC+dD                                                                                                                                                
MATHEMATICAL PROOF :-                                                                                                           Acording to law of mass action :-
 Rate of forward reaction proportional to [A]^a[B]^b
 Rate of forward reaction =Kf [A]^a[B]^b
 Rate of reverse  reaction proportional to [C]^c [D]^d
 Rate of reverse  reaction =Kr [C]^c [D]^d
 Where Kr and Kf are the rate constant for reverse and forward reactions respectively.
At equilibrium state
                                  Rate of forward reaction = Rate of reverse reaction
                         Kf [A]^a[B]^b = Kr [C]^c[D]d          
               
                        Kf / Kr  =[C]^c[D]^d / [A]^a[B]^b
                             
                       Kc=[C]^c[D]^d /  [A]^a[B]^b    IT IS KNOWN AS EQUILIBRIUM EXPRESSION

EQUILIBRIUM CONSTANT :-
                                                     Where Kc=Kf / Kr and is known as equilibrium constant.

UNIT:-

            The unit is mol/ dm^3.

Acid Rain

Defination :-
                      The rain having PH less than 5.6 Rain.

Explanation: -
                        Normal rain water is saturated with carbon dioxide.  It has PH of 5.6 however ; the acidity of rain greatly  increases in polluted areas during thunderstorm.Sulphur dioxide from power plants using fossil fuels and nitrogen oxides  from exhaust fumes of automobiles dissolve in rain water producing acids.
       2SO2 + O2 → 2SO3
Therefore,  during thunderstorms, the PH of rain water can be much lower because of sulphuric acid and nitric acids formed by lightening .This rain may have PH as low as 2.1. This value is lower than the PH of vinegar or lemon juice.
Sulphuric acid eats away metals to formvwater soluble salts and hydrogen
             Fe + H2SO4 →FeSO4 + H2
    Marble buildings and statues are slowly eroded by acid rain.
  CaCO3 + H2SO4 →  CaSO4 + H2O + CO2                 
Acid rain also kills fish, and destroys trees.Lakes and river may become too acidic for living things to survive.