Answer:
Water pollution may be defined as the contamination of the unwanted substance or pollutant with water that changes the normal characteristics of water. Three main contributors of ground water are as follows:
Chemical farming: The use of pesticides and fertilizers in the fields and its direct run off in river and groundwater causes the water pollution.
Industrial waste: The industrial waste consists of harmful chemicals and heavy metals. The direct discharge of chemical waste in the lakes, ground water and ponds makes the water dirty and causes water pollution.
Effluent from waste water treatment plant: The effluent and the harmful chemical waste release from the waste water treatment plant is the major contributor to the ground water. The effluents mix with the ground water and changes the ground water property.
To prevent blood flowing back after each heartbeat. They ensure that the blood flows only in one direction (back to the heart).
Answer is b. Burning fossil fuels causes a decrease in the pH of ocean water making it more acidic.
Burning of fossil fuels release carbon dioxide and other harmful gases in the atmosphere. Carbon dioxide gets dissolves in the ocean to form carbonic acid. Due to formation carbonic acid, the pH of ocean water changes slightly. The average pH of ocean water was 8.2 slightly basic. Now it 8.1, it means there is 25 % increase in acidity of ocean water.
The answer is C) selective breeding. This means that humans are deciding what to breed which means this is not a natural selection, but rather an artificial selection.
