Water and ocean conservation - class-X

Almost all the water on the earth is contained in the seas and oceans, rivers, lakes, ice caps, as groundwater and in the atmosphere.

• The earth is predominantly (71 % of the earth's surface) covered with water. Water absorbs the white light in the radiation (sunlight). The sunlight through appears white it is actually a combination of lights of several different colors (Violet, indigo, blue, green, yellow, orange and red). 
• When sunlight reaches the water; the water absorbs, lights of all colors in the white light and reflects only blue light. Thus, the earth from space appears blue. If the water absorbs all colors and reflects only yellow, then it would appear yellow.

Forests helps in producing rainfall. More are the trees, the more water gets absorbed into clouds and the more it helps in rain falls. The roots of a tree make gaps in the soil so that when it rains the water can sink in before being absorbed by the soil. These spaces also allow air and water to reach the roots of the plants.  If the forests disappear, there will be less rain resulting in dryer conditions, that eventually lead to drought. Once this happens, the damage is extensive making it difficult to plant more trees or plants later because the soil is so hard and dry. When trees removed using heavy machinery, the soil is pushed down and the gaps fill in. Because all plants and trees need that water and air to reach roots, the conditions become unfriendly for new growth.

Greatest problem in water conservation is to reduce the amount of evaporation. Evaporation is a process by which a large amount of water evaporate in the form of water vapours (gaseous form)

World Water Day is an annual United Nations observance day held on March 22nd to highlight the importance of freshwater.

Water-saving technology for the home includes:

• Low-flush toilets and composting toilets. These have a dramatic impact in the developed world, as conventional western toilets use large volumes of water. 
  
• Rainwater harvesting high-efficiency clothes washers weather-based irrigation controllers garden hose nozzles that shut off water when it is not being used, instead of letting a hose run. Low flow taps in wash basins. 
• Automatic faucet is a water conservation faucet that eliminates water waste at the faucet. It automates the use of faucets without the use of hands.
  

Water heavily may  result in root rot due to water logging preventing the roots from respiring aerobically. When roots respire anerobically alcohol produced as a byproduct results in root rot. Watering has to be done based on the season and the water requirement of the plant

Natural resources are of two types, exhaustible and non-exhaustible. Exhaustible resources are those natural resources that are available in limited quantity. Examples include coal, natural gas, petroleum. Non-exhaustible resources are those natural resources that are available in abundance. Renewable resources are those which can be recycled or replenished. The solar energy is renewable and non-exhaustible source. Water is a renewable but exhaustible resource. It may exhaust one day if used without any concern. 

The density of pure water at standard atmospheric pressure and 4 degrees Celsius is approximately 1000 kg/m3. Among the provided choices, 997 kg/m3 is the closest scientific approximation for water at room temperature.

Sea water is unsafe for drinking primarily because of its high salt concentration (approximately 3.5%). Drinking seawater would lead to dehydration as the body requires more water to excrete the excess salt than the water consumed. While other factors like pollution may exist, salinity is the primary reason.

Sodium (Na+) is the most abundant dissolved cation in seawater, followed by magnesium, calcium, and potassium.

The 'Sardar Sarovar Dam' is a gravity dam on the Narmada river near Navagam, Gujarat in India. It is the largest dam and part of the 'Narmada Valley Project'. 

Water conservation involves multiple strategies, including reducing waste, improving irrigation efficiency, and recycling industrial water. Therefore, all listed options are correct.

Conservation is the process in which the resources are used in a sustainable manner without affecting the environment. The water resources can be conserved by using drip irrigation which reduces the wastage of water. Recycling of water will help allow usage of the waste water for non-drinking purposes. Afforestation includes planting of more trees increasing the amount of rainfall. Thus, the correct answer is option C. 

MPCB is the Maharashtra Pollution Control Board. It implements a range of environmental legislation in the state of Maharashtra, India. The MPCB functions under the administrative control of Environment Department of the Government of Maharashtra.

Chemical fertilizers are the major source of contamination of ground water. Chemical fertilizers that is soluble in water gets dissolved in rain water or irrigated water and seeps inside the ground contaminating the groundwater.