Photoshop layers are like sheets of stacked acetate. You can see through transparent areas of a layer to the layers below. You move a layer to position the content on the layer, like sliding a sheet of acetate in a stack. You can also change the opacity of a layer to make content partially transparent.

Plastic use is increasing day by day and it is not only our country's problem it is worldwide problem because it is spoiling our environment rapidly . to overcome this situation we should put our hands together to stop usage of plastic in our daily life. As responsible citizens of our country help to protect our environment from plastic related pollution by following ways:

1 We should use jute bags and jute material instead of plastics.
2 We should not throw the plastics in the drain,river,ponds,lakes.
3  We should not burn plastics as this burning emits harmful gases and pollute the environment.

The reason behind the rapid rise in obesity in adults and children is the cheaply available foods and drinks high in fat, sugar, and salt. Overweight problem is prevalent in poor as well as rich countries.

The maximum displacement of a vibrating object from its Central position is called the amplitude of vibration. The amplitude actually tell us how far the vibrating object is displaced from its central position.

Cybercrime, or computer-oriented crime, is a crime that involves a computer and a network. The computer may have been used in the commission of a crime, or it may be the target. Cybercrime may threaten a person, company or a nation's security and financial health.

Geothermal energy is the energy obtained from the earth(geo) from the hot rocks present inside the earth. It is produced due to the fission of radioactive materials in the earth’s core and some places inside the earth become very hot. These are called hot spots. They cause water deep inside the earth to form steam. As more steam is formed, it gets compressed at high pressure and comes out in the form of hot springs which produces geothermal power.

Advantages of Geothermal Energy

1) It is a renewable source of energy.

2) By far, it is non-polluting and environment friendly. 

3) There is no wastage or generation of by-products.

4) Geothermal energy can be used directly. In ancient times, people used this source of energy for heating homes, cooking, etc.

5) Maintenance cost of geothermal power plants is very less.

6) Geothermal power plants don't occupy too much space and thus help in protecting natural environment. 

7) Unlike solar energy, it is not dependent on the weather conditions. 

Given : Volume of cylinder is 6358 cm cube and its height is 28 cm.

To find : Its radius and curved surface area?

Solution :

Volume of the cylinder is 

Where, V is the volume = 6358 cm cube

h is the height = 28 cm

r is the radius

Substitute the values,

The radius of the cylinder is 8.5 cm.

The curved surface area of the cylinder is 

r=8.5cm , h=28 cm

Substitute the value,

The curved surface area of the cylinder is 1496 centimeter square.

One of the major functions of cytoplasm is to enable cells to maintain their turgidity, which enables the cells to hold their shape. Other functions of cytoplasm are as follows:

• The jelly-like fluid of the cytoplasm is composed of salt and water and is present within the membrane of the cells and embeds all of the parts of the cells and organelles.
• The cytoplasm is home to many activities of the cell as it contains molecules, enzymes that are crucial in the break down of the waste.
• The cytoplasm also assists in metabolic activities.
• Cytoplasm provides shape to the cell. It fills up the cells thus enabling the organelles to remain in their position. The cells, without cytoplasm, would deflate and substances will not permeate easily from one to the other organelle.

Types of Plastics

1. Thermoplastic: Plastics which can be easily bent or deform on heating are known as thermoplastic. PVC and Polythene are the examples of thermoplastics.

2. Thermosetting plastic: Plastics which do not get deformed or softened on heating when mold once, are called thermosetting plastics. Bakelite and melamine are the examples of thermosetting plastics.

Uses of plastics

1. Plastic are poor conductors of heat and electricity. So they are used to make covering of electric wires and handles of tools.
2. Plastics are highly resistant to chemicals and water.
3. Plastics are lightweight, strong and durable and are therefore used to make parts for aircrafts, cars etc.

Hyper Text Markup Language

HTML is a markup language that web browsers use to compose text, images and other material on the web pages. Tim Berners-Lee invented the World Wide Web in 1990 to facilitate sharing and updating information on Web using HTML. To create web pages, text editor and web browser is required.

Exhaustible resources are those resources which are present in limited quantity and can be completely used up by human activities are called exhaustible resources.
 Exhaustible sources are those sources of energy, which will deplete and exhaust after a few hundred years.

Examples – Coal, petroleum, etc. are the exhaustible sources of energy.

Refining of petroleum

The crude petroleum oil is a complex mixture of solid,liquid and gaseous hydrocarbons.

So before petroleum can be used for specific purpose,it has to be refined or purified.

The process of separating crude petroleum oil into more useful fractions is called refining.

The refining of petroleum into different fractions is based on the fact that the different fractions of petroleum have different boiling point.

The refining of petroleum is carried out in an oil refinery.

The crude petroleum oil extracted from oil wells is taken to the oil refinery through pipes.In the oil refinery,crude petroleum is oil is refined into different useful fractions.

The separation of petroleum into different fractions is done by fractional distillation.The various useful fractions obtained by the refining of petroleum are:Petroleum gas,petrol,kerosene,diesel,lubricating oil,paraffin wax,Bitumen.

Those chemicals which are obtained from petroleum and natural gas are called petrochemicals.

For Ex:Methyl alcohol,ethyl alcohol,formaldehyde,acetone,acetic acid,ethylene,benzene,toluene,vinyl chloride etc.

They are important because they are used to manufacture large number of useful material such as detergents, synthetic fibres, plastics, synthetic rubber, drugs, dyes, perfumes, fertilisers, insecticides etc.

Hydrogen gas is obtained as a petrochemical from natural gas.It is used in the manufacture of fertilisers.

Petroleum is not only a source of fuels but also provides raw material for manufacture of large number of useful substances.Due to its great importance ,it is called black gold.

Fossil fuels

Exhaustible natural resources like coal, petroleum and natural gas were formed from the dead remains of living organism (fossils). So, these are called fossil fuels. Coal and petroleum are very important natural resources and play a vital role in modem society. They are found in the earth's crust.

It consist mainly of methane (about 85%), ethane (about 10%) propane (about 3%) and butane when natural gas is compressed at high pressure then it is called CNG (compressed natural gas). CNG is used for power generation.

It is now being used as a fuel for transport vehicles because it is less polluting. The great advantage of CNG is that it can be used directly for burning in homes and factories where it can be supplied through pipes. Such network of pjpeline exists in Vadodara (Gujarat) and some parts of Delhi.

This medication is used on the skin to treat the itching, scaling, and flaking due to skin conditions such as psoriasis or seborrheic dermatitis. Coal tar belongs to a class of drugs known as keratoplastics. It works by causing the skin to shed dead cells from its top layer and slow down the growth of skin cells. This effect decreases scaling and dryness. Coal tar can also decrease itchiness from these skin conditions.

(a) Coal is classified into four main types, or ranks: anthracite, bituminous, peat and lignite.

B) Fractions that are separated out include gasoline, diesel, kerosene, and bitumen. Fractional distillation allows a lot of useful products to be made from crude oil, with many environmental consequences for the use of those useful products

c. Sodium metal is kept in kerosene because sodium is very reactive metal. It is kept in kerosene to prevent it from coming in contact with oxygen and moisture. If this happens, it will react with the moisture present in air and form Sodium hydroxide. This is a strongly exothermic reaction, and lot of heat is generated. It will result out in the form of fire.

1. Metal alloys have improved and unique property of hardness and sonority. Also, alloys have excellent ductility. Therefore metal alloys are used for making bells and strings of instruments. For example, bronze is used for making bells and stringed instruments.

Draw a line segment BC with the help of scale.
Take a compas and feel the radius of 4 cm and draw an arc of 90° which is point D and perpendicular to the point C.
Join DC = 4cm
Similarly, Feel the radius of 4.5 cm and draw an arc which is point A at the another side of line segment BC which is perpendicular to the point B.
Join AB = 4.5 cm
Then join the AD = 6 cm 
and hence we can find automatic AC which is 7 cm and diagonal of quadrilateral ABCD.

A n s w e r
Smooth and polished surface provides least friction. eg: polished marble, frozen river etc.
As the coefficient of friction (μ) is less for smooth surfaces 
so they produce less friction than rough surface.
 

Smooth surface produces less friction.

6p(p – 3) + 1 (p – 3)

= 6p (p) - 6p(3) + 1(p) - 3 (1)

= 6p² - 18p + p - 3

=  6p² - 17p - 3