Answer: Option D. -> Oceans
:
D
Freshwater is the name given to the part of water available on earth which is not salty and is fit for use. Rivers, polar ice caps and groundwater all fall under the category of freshwater. Oceans on the other handcontainsalty water. Hence, oceans are not a source of freshwater.

Answer: Option D. -> Drip irrigation
:
D
Drip irrigation is a type of irrigation in which plants are watered by using narrow tubings, which deliver the water to the plant slowly and directly to the base of the plant. This reduces the total amount of water required for agriculture and, hencehelps in water conservation.

Answer: Option B. -> Most of the available water is salty and unfit for consumption.
:
B
Though, about 71% of the Earth’s surface is covered with water, we still face water shortages because most of the water is available in oceans. Thiswater is salty and cannot be used for our day to day activities.
The water in lakes and rivers is also getting polluted everyday. The level of groundwater is also going down. We need to make sure that we use water judiciously so that freshwater is available for everyone.
We can adopt techniques such as rainwater harvesting so that we can save rainwater for future use.

Answer: Option A. -> True
:
A
Excessive irrigation is a loss in two ways, firstly it might damage the entire crop and secondly, it causes wastage of precious freshwater which just flows away.

Answer: Option A. -> True
:

Each source: 0.5 Mark
Any two source
Various sources of freshwater are:
i) Lakes
ii) Ponds
iii) Groundwater
iv) Rivers

Answer: Option A. -> True
:
Naming: 0.5 Mark each.
The conventional methods used for the purification of water are as follows:

1. Boiling


2. Sedimentation


3. Using Alum


4. Chlorination

Answer: Option A. -> True
:
Factors: 2 Marks
The factors that help the rainwater to seep into the soil are as follows:
(i) Duration of precipitation
(ii) Type and strength of precipitation
(iii) Type of soil
(iv) The land cover, like, areas in which there are more plants, infiltration or seeping will take place more easily

Answer: Option A. -> True
:
Explanation: 2 Marks
When freshwater freezes, water molecules of hydrogen and oxygen bond together into a crystalline form called ice. In seawater, the presence of salt makes it harder for water molecules to bond to the ice structure because ice naturally repels salt molecules. So in a sense, the salt gets in the way of water molecules, blocking them from joining together to form ice.

Answer: Option A. -> True
:
Steps of the water cycle: 2 Marks
The various steps in the water cycle are as follows:

• Evaporation


• Transpiration


• Condensation


• Precipitation


• Infiltration


• Runoff

 

Answer: Option A. -> True
:
Definition: 1 Mark
Reasoning out: 1 Mark
Explanation 1 Mark
Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in the air. The measurement of turbidity is a key test of water quality.
The turbidity of water is based upon a comparison of the amount of light passing through a given water sample with that passing through a standard sample. Usually, this is defined in terms of the depth of water to which a candle flame can be clearly distinguished.
Turbidity is caused by particles suspended or dissolved in water that scatter light making the water appear cloudy or murky. Particulate matter can include sediment - especially clay and silt, fine organic and inorganic matter, soluble colored organic compounds, algae, and other microscopic organisms.