Objective:-(1)To prepare a temporary mount of onion cells,(2)to record observations and draw labelled diagrams

Materials Required:-
Onion Knife,Forceps,Blade,Slides,Watch glass ,cover slip,brush,
compound microscope,blotting paper,
Safranine ,Glycerine and water.

Procedure:-
(1)Take a piece of onion scale and bend it until it breaks into two.When it breaks,you will notice that a thin membranous structure still connecting the two bits.This membranous structure is called onion peel .

(3)take some water in a watch glass and put the epidermis in it.Make certain that it is not folded or rolled.

(4)Add 1-2 drops of Iodine solution or Safranine solution.

(5)After about 2-3 minutes take the peel and wash in acid water if Iodine solution is used or in plain water If safranine is used.

(6)Take a clean glass slide and put a drop of glycerine almost in the middle of the slide.

(7)Place the stained piece of the peel in the glycerine and put a cover slip on it.

(8)Soak the overflowing fluid from the corners of the coverslip with the help of the blotting paper and clean the side.

(9)Observe the wet mount under the  microscope .

(10)Draw the diagram of the peel and label .

Observations:-

(1)Under Low power of te microscope

1.The rectangular cells of onion  are seen.The regularly arranged components like cells have clear outline.

2.A deeply coloured,round body is seen in side every cell.This is known as Nucleus.

Precautions- Too much of stain should not be used .
      Microscope should be handled carefully.

Vivekanand contest

All the  students are requested to read the book -The life and teachings of Swami Vivekanand online through the website         www. awakening       india .org for the forthcoming 
Vivekanand contest
 to be held on 13th August i.e. tuesday in the zero period.

Value based question

-In  Pitam  pura  market  ,kareena,katreena and priyanka go for shopping of grocery items .They find that the shopkeeper mixes harmful and cheap substances with th food items like white stones with rice ,papaya seeds with black pepper and brick powder with red chilies .
Answer the following questions
Q1  What is the name of this malpractice?
Answer- Food Adulteration.

Q2   What can the reason for such a practice?
Answer- To earn more profit .

Q3  Do you think the shopkeeper is doing the right thing? give reasons?

answer-This is really a bad practice because it can cause serious health problems and also we are paying more for poor quality food .

Question4- What steps should be taken to stop adsulteration/

Answer-1 We should buy things from reliabl;e shops .
2  We must buy packed food and read the instructions given on the wrapper.
3 We must report if we find any adulteration.

Assignment 2 on chapter separation of substances

Question 1
Suggest ways to separate a mixture of

(a) camphor,sand and salt.
Answer- steps
1 Sublimation
2 filtration
3 evaporation


(b) Saw dust, common salt and iron nails
steps
1 magnetic separation
2 filtration
3 evaporation

(c)ammonium chloride ,common salt and chalk powder

Steps
1 sublimation
2  filtration
3 evaporation

Question 2 Define Adulteration,harvesting and Evaporation

Answer- Adulteration Mixing harmful and cheap substances with the pure
substance to gain more profit is called adulteration.

Harvesting-The process of cutting and collecting the ripened crop is called harvesting.

Evaporation-The process in which liquid changes into gaseous state
on heating is called evaporation.

Assignment -chapter Separation of substances

Q- How can you separate the mixture of iodine and sand?  Explain and draw the diagram also.

Answer1-  Take a mixture of sand and iodine in a china dish .
Cover it with an inverted funnel whose narrow end is closed with cotton wool.
Heat the china dish on a wire gauge.

Observation-We observe that on heating iodine sublimates and changes into vapor and rises up.
On coming in contact with walls of funnel it cools down and changes back into solid state
 and sticks to the walls of the funnel and is left behind in the cotton of the funnel.
Result=  Sand and iodine are separated from each other by the process of sublimation.




Question 2   Write an activity to separate mustard oil and water ?Draw the diagram .

Answer 2    
Aim-To separate mustard oil and water.
Material required-Separating funnel, water ,mustard oil, stopcock,beaker and stand.

Procedure-Pour the mixture of water and oil into separating funnel .
  Let it stand for sometime so that separate layers of water and oil  are formed.
Put the stop cock off so that the water slowly starts flowing down and gets collected in the beaker .
Oil will be left behind in separating funnel.
Result-Oil and water are separated by the use of separating funnel.