Page 117 - Innovator's Science-8

It has been found that for most substances, solubility increases with an
Science increase in temperature. We can also say that a saturated solution at a
Bytes

particular temperature behaves as an unsaturated solution if the
Testimony
What inspired Asima temperature is increased.
Cha erjee to work on Many gases, including oxygen, dissolve in water to form a uniform mixture
medicinal plants? Asima
Cha erjee is renowned called a solution because the gases spread evenly throughout the water.
for her work in Although oxygen dissolves only in small amounts, this dissolved oxygen is
developing an -epilep c
and an -malarial drugs. crucial for aquatic life such as fish, plants, and other organisms living in
She used solvents and water. Temperature does affect how
solu ons extensively to much gas can dissolve in a liquid;
extract and isolate
important compounds generally, as the water temperature
from medicinal plants. rises, the solubility of gases like oxygen
She earned a Doctorate
of Science, becoming the decreases. This means cold water holds
second Indian woman to more oxygen, which supports aquatic life
do so a er Janaki Ammal. better, while warm water holds less
She became the first
woman to receive the oxygen, which can make it harder for
Shan Swarup Bhatnagar aquatic organisms to survive. So, cooler Aquatic species in water
Award in the field of
chemical science and was water is better for keeping enough oxygen dissolved to sustain life in ponds,
also honoured with the lakes, and oceans.
Padma Bhushan.
WHY DO OBJECTS FLOAT OR SINK IN WATER?

You might have seen that some objects float in water while others sink. For
example, when washing rice, the husk floats on water, but the rice sinks.
This happens because of a property called density, which means how heavy

something is for its size. An object floats if its density is less than the water's
density, and it sinks if its density is more. For
instance, a wooden stick and an iron rod can

be the same size, but the iron rod is much
heavier because its density is higher. So,
objects with lower density than water float,
and those with higher density sink. This is
why oil floats on water too, because it is less Some objects float while

dense. This principle explains why some others sink in water
things stay on the surface while others go to the bottom of water.

WHAT IS DENSITY?

Density describes how much space an object or substance takes up.
Density represents how thick or closely packed together an object of

substance is. Density can vary depending on temperature and pressure.

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