Page 124 - Science Class 6 Times Publication

Observation: The ame of the candle becomes smaller and at last

it gets extinguished. When the candle gets extinguished, the water
level increases slightly inside the bell jar.

Conclusion: Here, when the candle burns inside the bell jar, all the
oxygen inside the bell jar is used up for burning. The water from the
vessel goes upward to the bell jar to occupy the place of the oxygen.

Now, place a burning splinter inside the same bell jar. The splinter
gets extinguished due to absence of oxygen. This experiment proves
that air contains oxygen.
Carbon dioxide

Carbon dioxide occupies 0.03% of the total volume of air. It is heavier
gas. It is mostly found in large amount in the caves, deep well, and
in lower altitude.

Carbon dioxide is used by plants for the preparation of food during
photosynthesis. Animals depend upon plants for food. Carbon dioxide
is used in some drinks like coca-cola, sprite, beers etc. Carbon dioxide

is used as re extinguisher (for putting out re). You must have seen

cylinders of carbon dioxide kept in hospitals, schools, ofces, etc for
emergency use.
Activity 11.2

To prove that air contains carbon dioxide

Materials required: A beaker, hand pump and lime water
Procedure

1. Take a beaker and put a little lime water in
the beaker.

2. Pump air inside the lime water with the
help of the hand pump as shown in the
gure. What will you observe?

Observation: The lime water slowly turns into milky colour.

Times' Crucial Science and Environment 120 Book 6