Mumtaz Jarra

Eye Defects 
MYPOPIA
Myopia is also known as near- sightedness. A person with myopia can see nearby objects clearly but cannot see distant distinctly. A erson with this defect has tje far point nearer than infinity. Such a person may see clearly upto a distance of few metres. In a myopic eye , the image formed in front of the retina and not on at the retina itself. This defect may arise due to excessive curvature of the eye lens or elongation of the eyeball.

Hypermetropia
Hypermetropia is also known as far- sightness. A person with hypermetopia can see distant objects clearly but cannot see nearby objectsobjects distinctly. The ner point for the person is farther away from the normal near point (25cm) . Such   a person  has to keep a reading material much beyond 25 cm from the eyefor a comfortable reading. This is because the image in formed behind the retina. This defect arises because the eyebll has become too small.

Presbypoia                                                                                                                          

The power of accommodation of the eye usually decreases with ageing. For the most people ,the near point gradually recedes away. They find it difficult to see nearby objects comfortably nd distinctly without corrective eye glasses. This defect is called Presbypoia.

ACOMMADATION  

THE ability of the eye lens to adjust its focal length is called accommodation . however the focal length of the eye lens cannot be decrease below a certain minimum limit. To see an object comfortably nd distinctly the minimum distance at which objects c be seen is 25 cm

keshav chemical eqation and reaction

ACTIVITY: TO SHOW THE BURNING OF MAGNESIUM RIBBON

* Material required:

 1) Magnesium ribbon

 2) Sand paper

  3) Matchbox 

* METHOD: 

 1) Rub the magnesium ribbon with sand paper to remove the layer of magnesium oxide

  2)  Burn the magnesium ribbon.

*  OBSERVATION:  the ribbon burn with dazzling white light 

* CONCLUSION: the white powdery product formed is magnesium oxide.

 IN  THE FORM OF CHEMICAL EQUATION:

   2  Mg (s)  +  O₂ (g)  →  2 MgO (s

sakshi roll no. 13 chemical equations

 date: 21/06/17

               chemical equation and reactions

ACTIVITY: TO SHOW THE BURNING OF MAGNESIUM RIBBON

* Material required:

 1) Magnesium ribbon

 2) Sand paper

  3) Matchbox 

* METHOD: 

 1) Rub the magnesium ribbon with sand paper to remove the layer of magnesium oxide

  2)  Burn the magnesium ribbon.

*  OBSERVATION:  the ribbon burn with dazzling white light 

* CONCLUSION: the white powdery product formed is magnesium oxide.

 IN  THE FORM OF CHEMICAL EQUATION:

   2  Mg (s)  +  O₂ (g)  →  2 MgO (s)

VAISHNAVI - Chemical Reactions​ & Equations

CHEMICAL REACTIONS AND EQUATIONS

                                            21/6/17

Activity on magnesium ribbon:

Materials required: magnesium ribbon ,
                                    matchbox,
                                    candles or burner

Procedure:

             Clean a magnesium ribbon by rubbing with a sand paper so that the carbonate gets removed from the surface of the magnesium ribbon. Now burn it with a candle or with a burner, we observe the magnesium ribbon burns in air with a dazzling flame and changes into white powder. The powder is formed due to the reaction between magnesium and oxygen.

It can be expressed as :   2Mg + O₂ ­­­­-------->  2MgO

mumtaz

Chemical

reactions and equation.
Acitivity : to show the burning of magnesium is a chemical change

When a magnesium ribbon is heated ,it burns in air with a dazzling white falme to form a white powder called magnesium oxide. Actually , on heating , magnesium combines with oxygen present in air to form magnesium oxide:
         Magnesium   +   oxygen  ~heat   ~ magnesium oxide
The burning of magnesium in air to form magnesium oxide is an example of a chemical reaction.so,before burning in air ,the magnesium ribbon is cleared by rubbing with a sand paper. This is done to remove the protective layers of basic magnesium carbonate from the surface of magnesium ribbon.

ayush sharma roll no -28

Chemical Reaction and Equations

21-06-2017
Experiment with Magnesium Ribbon

Material: Magnesium Ribbon, Candle, Matches
Objective: To observe the reaction of Magnesium with Air.
Process: First take a magnesium ribbon and rub it with sandpaper so the layer of carbonate gets removed from the surface of magnesium.
Now burn the candle and take the magnesium ribbon near the flame and hold it there for some time and then you will witness that the magnesium ribbon burns with a dazzling white flame and after it is completely burnt you will that only ash remains.
We can write the chemical equation as:-
2Mg + O2 ­­­­-------->  2MgO

Aarush Sinha --- Roll NO. 22 ----- Chemical Reactions and equations

Chemical Reaction and Equations

21-06-2017

Experiment with Magnesium Ribbon

Material: Magnesium Ribbon, Candle, Matches

Objective: To observe the reaction of Magnesium with Air.

Process: First take a magnesium ribbon and rub it with sandpaper so the layer of carbonate gets removed from the surface of magnesium.

Now burn the candle and take the magnesium ribbon near the flame and hold it there for some time and then you will witness that the magnesium ribbon burns with a dazzling white flame and after it is completely burnt you will that only ash remains.

We can write the chemical equation as:-

2Mg + O₂ ­­­­-------->  2MgO