Page 15 - Chemistry - XI

5. Fitting the glass tube in the bore:

a. Wet the cork with water.
b. Wet the end of the tube which is to be inserted in the bore with water/glycerine.
c. Hold the tube closely from the wetted end in the right hand with a cloth.

d. Hold the cork in the left hand.
e. Insert the tube into the bore giving a rotatory motion slowly.

f. The hole of rubber cork should be dipped in glycerine so as to make rubber cork soft and then glass
tube should be inserted.

Straight hole

Right hole in Cork
Wrong hole (at an angle)

Moistened End

Right Hand

Fig. 4.2

VIVA VOCE

Q1. Why is it necessary to put marks on both the sides of the cork?
Ans. It is done so as to get a vertical hole.

Q2. Which borer is of the right size for boring?
Ans. The borer whose outer diameter is equal to inner diameter of the glass tube.

Q3. Why is the cork moistened and pressed before boring?
Ans. It is done so as to avoid cracking and to get smoother bore.

Q4. While inserting the glass tube into the bored cork, why should the glass tube be held close to
the cork?
Ans. Otherwise, it may break which may cause injury.

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