let x be 1st angle and y second
y = 2x
x + y = 180
x +2x = 180
3x = 180
x = 60
y = 2x = 120

The dirty water which contains various impurities like dust, polythene bags, Vegetable peels, kitchen waste, oil & water that goes down the drains from sinks, showers, toilets, laundries etc. is waste water. Waste water cannot be used further.

Sewage is waste water released by homes, industries, hospitals, offices and other users. It also includes rainwater that has run down the street during a storm or heavy rain. The water that washes off roads and rooftops carries harmful substances with it. Sewage is a liquid waste which has dissolved and suspended impurities as contaminants or pollutants. If this untreated sewage is discharged into rivers or seas, 

 The various sources of waste water are:
a. Agriculture: Wastewater from farms contain pesticides and animal wastes.
b. Industries: Wastewater generated from certain industries contains toxic chemicals such as lead and chromium.
c. Mining and Constructions:  Large amounts of waste water is generated from mining methods and wastewater generated from constructions contains cement and other compounds
d. Hospitals and Offices: Waste water generated from hospitals and offices contain bacteria and germs
e. Domestic activities: Waste water generated from domestic activities includes solid particles like metal, plastics, detergents and human faeces.

Eutrophication is the process in which a water body becomes overly enriched with nutrients, leading to plentiful growth of simple plant life. The excessive growth (or bloom) of algae and plankton in a water body are indicators of this process. Eutrophication is considered to be a serious environmental concern since it often results in the deterioration of water quality and the depletion of dissolved oxygen in water bodies. Eutrophic waters can eventually become “dead zones” that are incapable of supporting life.

Eutrophication may be defined as the inorganic nutrient enrichment of natural waters, leading to an increased production of algae and macrophytes. Many lakes are naturally eutrophic and in some cases there is a progressive eutrophication as the lake matures. The term Eutrophication is more widely known in relation to human activities where the artificial introduction of plant nutrients has led to community changes and a deterioration of water quality in many freshwater systems. This aspect has become increasingly important with increases in human population and more extensive development of agriculture and eutrophication now ranks with other major anthropogenic effects such as deforestation, global warming depletion of the ozone layer and large scale environmental disturbance in relation to its potentially harmful effect on natural ecosystems.

sludge is the organic waste which settles at the bottom of the first sedimentation tank

Scum is the organic waste which contains waste less denser than water like grease oil etc

Water is removed from the top and is stored in a tank. The treated water has low level of organic material and suspended matter. It is discharged into a sea, a river or into the ground. Sometimes it is disinfected through chemicals like Chlorine and ozone and then distributed to towns.

Biogas is also called as gobar gas. This gas primarily consists of carbon dioxide and methane. It is a renewable energy source. Biogas is produced due to the decomposition of organic matter. This process occurs through anaerobic digestion. When plant or animal waste is broken down by bacteria in the absence of oxygen they release gases such as carbon dioxide and methane.

Uses of Biogas

i) It is commonly used in ruler area as cooking gas.

ii) It can be used for the production of electricity.

Cocoons are collected and kept under the sun, or boiled, or exposed to steam. This helps in separating out the silk fibres. The process by which silk thread is separated from the cocoon is called reeling the silk. The boiling of cocoon leads to formation of vapours that can pollute the environment and also cause respiratory problems. It is for this reason that sericulture is not  considered as an eco-friendly practice.

The workers of sericulture industry often develop asthma ,chronic bronchitis and difficulty in breathing due the liberation of allergy causatives during the development of silkworm. The allergens from the silk worm excrete, silkworm cocoon, scales and the cuticles of the abdomen and wings of the silk moth are the main causative agents of the asthma and other respiratory problems. 

Sericulture is a process of rearing silk worms for silk production. Healthy moths are selected to lay eggs as the eggs hatch once in a year. These eggs are washed and stored. Larvae that hatch from the eggs are spread on wooden trays, fed with chopped mulberry leaves and allowed to grow. After 20 – 35 days, twigs are placed on the trays, on which the worms start spinning their cocoons. This may take about 3 – 7 days. Once the cocoons are completely built, they are put in hot water, for reeling, in which the worms are killed and the filaments of silk are drawn from the cocoons.. Filaments from several cocoons are wounded on a reel, which are then dyed and woven into a silk fabric.

Sorter job in wool industry is a risky job because it makes the worker the victim of serious and highly fatal bacterial disease called ANTHRAX which affects the blood system of the body.

In the process of wool manufacturing, once the skin of the sheep is removed along with thin layer of skin, it must be processed to second stage called sorting in which skin which of good quality must be identified by the worker through sense of touch. As the skin of the animal may have many contaminants including dirt, bacteria etc it may lead to fatal blood infection.

Sheep shearing is always done after winter because in summer season the day is hot so the sheep can surive without there fur and before winter come there fur comes again.And if there fur is taken out in winter they will die.For that the sheep don't die the sheep keepers take out there fur in winter.And again share its fur in summer season.

1. Take a cupful of water in a beaker and add a few drops of dilute sulphuric acid.
2. Heat the water.
3. When it starts boiling, add copper sulphate powder slowly while stirring continuously.
4. Continue adding copper sulphate powder till no more powder can be dissolved.
5. Filter the solution.
6. Allow it to cool. Do not disturb the solution when it is cooling.
7. Crystals of copper sulphate will be seen at the bottom of the beaker.

 Extracellular digestion is a process which is carried out of the cell, where the food is broken down into simple substances by specific molecules known as enzymes.
Extracellular digestion takes place in fungi and other decomposers.
Fungi with the help of enzymes or chemicals break down the food they live on and then absorb the nutrients.

An amylase or ptyalin present in saliva, that catalyzes the hydrolysis of starch into maltose and dextrin. An enzyme found in the saliva of humans and herbivorous animals that helps in the pre digestion of starches. Ptyalin is a type of amylase. Pepsin, rennin and lipase are absent in saliva.

Digestion in Amoeba is intracellular, as it takes place within the cell.

Tentacles is the food processing structure present in hydra.

Pangolin or Manis are commonly called scaly anteaters. They have a protective covering of sales on their bodies which are basically made up of keratin. They are nocturnal animals and mainly feed on ants and termites. They have long protrusible tongues that help them to catch ants and termites The presence of sticky saliva on their tongues also enhance their ability to catch their prey.

The mouth parts of Lepidoptera mainly consist of the sucking kind; this part is known as the proboscis or 'haustellum'. The proboscis consists of two tubes held together by hooks and separable for cleaning. The proboscis contains muscles for operating.

The steps are as follows:-

1) Ingestion: The process of taking food into the body is called ingestion.
2) Digestion: the process in which the food containing large, insoluble molecules is broken down into small, water soluble molecules is called digestion.
3) Absorption: The process in which the digested food passes through the intestinal wall into blood stream is called absorption.
4) Assimilation: The process in which the absorbed food is taken in by the body cells and used for energy, growth and repair is called assimilation.
5) Egestion: The process in which the undigested food is removed from the body is called egestion.