CHEMISTRY [1 Mark Question Answer]

Water (solvent).

Water cycle.

Snow.

Insecticides.

Chlorine.

The gaseous state of water in air: Gaseous State as water vapour in the air the amount depending on climatic conditions.

A saturated solution cannot dissolve more of the solute at a given temperature.

Drip irrigation in agriculture utilizes a supply of water in small quantities.

Boiled water is deprived of oxygen i.e. there is no oxygen. For want of oxygen animals die in boiled water.

Two factors are :
1. Stirring.
2. Increase in temperature

A solution that can take up more of the solute at a given temperature, is said to be an unsaturated solution.

When a solution cannot dissolve any more of solute at a given temperature, it is called a saturated solution.

A solution is a homogeneous uniform mixture formed by a solute and a solvent

A solvent is a medium in which a solute dissolves. It is in large quantity in a solution. Water is the most common solvent. The other solvents are alcohol, carbon tetrachloride, etc.
Example: Water

A solute is a substance that dissolves in a medium which can be water or any other substance. A solute is in a smaller quantity in a solution. e.g. sodium chloride..

As water can dissolve in most of the substances, solids, liquid, and gaseous. Therefore it is called a universal solvent.

This anomalous property of water enables aquatic plants and animals to survive in colder regions of the world because even when the water of ponds, lakes, river freezes it freezes on the top but remains a liquid below the ice layer.

Water has a maximum density at 4°C. Ice is lighter than water therefore it floats on water.

Taste of water is tasteless i.e. flat. It is because distilled water does not contain any salt or mineral required for our body. So it is not potable water.

To kill harmful micro-organisms present in filtered water, air under pressure is blown into the filtered water. This process is called aeration.

The process of adding a chemical to an impure liquid in order to increase the speed of sedimentation of suspended particles is called loading.

The setting of suspended solid matter at the bottom of a liquid is called sedimentation.

The process of removal of microorganisms including bacterial spores from water to avoid water borne diseases is known as sterilisation

Water in the swimming pool kept free from infections and germs by chlorination i.e. treating water with chlorine gas.

Chemically pure water for laboratories is obtained-by distillation. Distilled water does not contain any salt or mineral.

Adding bleaching powder to water kills germs and harmful bacteria and viruses present in water.

Mineral water is pure water fit for drinking. It is collected from natural sources and contains air, minerals, and salts free from suspended impurities, harmful bacteria, and germs.

Tap water contains, minerals, air, chlorine, and other dissolved impurities that varies from place to place, therefore it is a mixture.

River water contains mineral salts, suspended impurities like clay, sand particles, organic matter and bacteria and is not fit for drinking.

Methods to get safe drinking water:
1. Adding chlorine tablets.
2. By adding potassium permanganate crystals.

Minerals and carbon dioxide gas add taste to water.

Chemical used for loading is potash alum.

Two diseases are cholera, dysentery

Two chemicals used to kill germs in water are:
1. Chlorine.
2. Potassium permanganate.
3. sterilizing water with ozone.

When the dew freezes it is called frost.

When the water vapour condenses on cold objects like grass, leaves, and flowers in winter in the form of tiny droplets of water called dew.

When tiny droplets of water remain suspended in air it is called mist.

When water vapours change into tiny droplets of water near the ground, fog is formed.

Water from the surface of the earth, lakes, seas, rivers, formed by plants (transpiration), etc. evaporates and rises high up in the atmosphere and condense into water droplets and collect to form cloud

Three states of water are :
1. Ice (solid)
2. Liquid (water)
3. Gaseous (steam)

Percentage of water in Watermelon : 97%

Percentage of water in Bread:25%

Percentage of water in Tomatoes: 95%

Percentage of water in Eggs: 75%

Percentage of water in Rice:
Rice — 3 % to 4%
Wheat grain — 3% to 4%

Three major impurities present in river water :
1. Suspended impurities like clay and sand particles.
2. Harmful bacteria.
3. Mineral salts.

Springwater contains unsolved impurities which have entered the water from surrounding soil and soil impurities (salts) differ from place to place. Hence the taste of water differs from place to place.

Level of ground water is called water table

The impurities present in rainwater are dust and dissolved gases like oxygen, nitrogen, and carbon dioxide and these gases are not poisonous, rainwater is safe for drinking.