Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". ... Some examples of metamorphic rocks are gneiss, slate, marble, schist, and quartzite. Sedimentary rocks, formed from the products of weathering by cementation or precipitation on the Earth's surface. Metamorphic rocks, formed by temperature and pressure changes inside the Earth. All three types of rock make up the Earth's lithosphere, the outermost layer. ... Quick cooling lavas are called volcanic rocks.

Metamorphic rocks are formed from other rocks that are changed because of heat or pressure. They are not made from molten rock – rocks that do melt form igneous rocks instead. Earth movements can cause rocks to be deeply buried or squeezed. As a result, the rocks are heated and put under great pressure. Rock that was once one form of rock but has changed to another under the influence of heat, pressure, or some other agent without passing through a liquid phase. Metamorphic rocks were once igneous or sedimentary rocks, but have been changed (metamorphosed) as a result of intense heat and/or pressure within the Earth's crust. They are crystalline and often have a “squashed” (foliated or banded) texture.

Retailers provide important services to consumers and wholesalers as they act as middle-men between them.
Services to consumers:

1. Ready or quick supply : The most important service of a retailer to consumers is to maintain regular availability of various products so that the buyers can buy the products whenever they need.
2. Wide variety : Retailers generally keep stock of a variety of products and different manufacturers. This enables the consumers to make their choice out of a wide selection of goods.
3. Guiding customers : By ananging the effective display of products and through their personal selling efforts retailers should provide the information of products to the customers.
4. Demonstration and after sales services : It can be done in the form of home delivery, supply of spare parts and attending to customers.
5. Home delivery : It is an important part of after sale services and for a buyers decision for repeat purchase of the products.
6. Convenient location : They are suitated very near to the residential areas and remain open for long hours which makes great convenience to the customers.
   Services to wholesalers and manufacturers :
7. Ready market: Retailers deal with individuals so the manufacturers and whole-salers will not make individual sales.
8. Providing information : By undertaking personal selling efforts retailers relieve the producers of this activity of individual selling.
9. Risk bearing : Retailers participates in the promotional activities of the product so that the product becomes popular and then it is less risk for the manufacturers.
10. Distribution of goods to distant places : Retailers helps in distribution of goods to the final consumers and thus provide place utility.

The functions of retailers are as follows :

1. Financing : Retailers provide goods to the consumers on credit basis. This increases the level of consumption and hence the standard of living.
2. Supplying market information : Since the retailer is in direct contact with the consumers, he provides information regarding their tastes, preferences and attitudes, etc. to the wholesaler. This information helps them in taking important marketing decisions.
3. Convenience in buying : Retailers provide goods to the consumers according to their requirements. Usually, they are situated near the residential areas and remain open for long hours.
4. Risk bearing : A retailer has to bear the risk if the change in style and fashion occurs when the goods are stored in large quantities in the warehouses.

Services provided by wholesalers are as follows:

1. Buying and assembling : The wholesaler buys the product from the manufacturer and collects the same at one place and supplies goods to the retailers according to their requirement.
2. Storage function : The wholesaler also performs the storage function. The goods are purchased by the wholesalers from the manufacturers and stored at warehouses in order to meet the demand of retailers. The wholesalers act as bridge between the production and consumption of goods.
3. Breaking the bulk : The wholesaler purchases goods from manufacturers in bulk and avails discounts. He sells goods in small quantities to the retailers which saves the retailers from maintaining large stocks.
4. Advertisement : A wholesaler undertakes advertising and sales promotion of the product which automatically result in the increase in sales.
5. Market information : Wholesalers inform the retailers about the introduction of new products in the market. He also gets feedback from the retailers about the needs and preferences of customers. He passes the information to the producer to make necessary changes in the products.
6. Risk bearing : The wholesalers have to maintain optimum levels of stock in their godowns to meet the demands of the retailer. The retailer’s risk of maintaining godowns, price fluctuations, etc., are
   reduced to a great level.

Internal Trade also known as Domestic Trade is the buying and selling of goods and services within the confines of the international boundaries of a nation. So while import and export are important for the economy of a nation, most of its GDP contribution comes from internal trade. 

Some of the common incentives provided by the government far industries in backward and hilly areas are as fallows
(i) Land Every state offers developed plots for setting up of industries. The terms and
conditions may vary. Some states don’t charge rent in the initial years, while some allow ’ '
payment in instalments.
(ii) Power Power is supplied at a concessional rate of 50 %, while some states exempt such units from payment in the initial years.
(iii) Water Water is supplied on no-profit, no-loss basis or with 50 % concession or exemption from water charges for a period of 5 years.
(iv) Sales Tax In all union territories, industries are exempted from sales tax, while some states extend exemption for 5 years period.
(v) Octroi Most states have abolished octroi.
(vi) Raw Materials Units located in backward areas get preferential treatment in the matter of allotment of scarce raw materials like cement, iron and steel, etc.
(vii) Finance Subsidy of 10-15 % is given for building capital assets. Loans are also offered at concessional rates.
(viii) Marketing Assistance Government tries to solve their marketing problem by improving information and in order to provide guarantee for sale of goods.
(ix) Tax Holiday Exemption from paying taxes for 5 or 10 years is given to industries established in backward, hilly and tribal areas.

Isomerism is the phenomenon in which more than one compounds have the same chemical formula but different chemical structures. Chemical compounds that have identical chemical formulae but differ in properties and the arrangement of atoms in the molecule are called isomers. Therefore, the compounds that exhibit isomerism are known as isomers.

The word “isomer” is derived from the Greek words “isos” and “meros”, which mean “equal parts”. This term was coined by the Swedish chemist Jacob Berzelius in the year 1830.

The plate movements are classified into three types:
(i) Some plates come towards each other and form convergent boundaries.
(ii) Some plates move away from each other and form divergent boundary.
(iii) At times, they may also move horizontally past each other and form transform boundary.
When two plates come together, they are known as convergent plates. They are also known as constructive plates. When two plates move far away from each other, they are known as divergent plates. When two plates coming towards each other collide or burst pass, they are known as transform plate. The movement of plates causes volcanic eruptions, earthquakes, formation of mountains, etc.

When goods are returned to a supplier, a debit note is prepared to represent the difference in the quantity. It contains the name of the party (supplier) whose account has been debited, along with the amount and details of the bill and the reason for the debit, in reference to which his account has been debited.
On the other hand, when goods are received back from the customer, a credit note is sent to him, indicating that the customer’s account has been credited in the books.

In physics Coriolis effect is a deflection of moving objects when they are viewed in a rotating reference frame In a reference frame with clockwise rotation, the deflection is to the left of the motion of the object; in one with counter-clockwise rotation, the deflection is to the right.

The Coriolis effect is the one that makes low pressures rotate anti-clockwise in the northern hemisphere and clockwise in the southern. At the equator, the forces cancel each other out. That's why the direction of rotation changes between the two hemispheres.

The Coriolis effect is greatest at the poles and zero at the equator because of the earth's spherical shape. If the surface of the rotating object is flatter, the Coriolis effect will be noticed more.

Here, Mass of machine gun , M = 20 kg
mass of each bullet , m = 35 kg = 0.035 kg
velocity of bullet υ=400m/sυ=400m/s
Number of bullets/sec (n) =400/60=20/3 
Force required = rate of change of linear momentum of bullets =n(mυ)/t = 20/3  × 0.035×400/1 =93.3N 

Developed from the 1950s through the 1970s, plate tectonics is the modern version of continental drift, a theory first proposed by scientist Alfred Wegener in 1912. Wegener didn't have an explanation for how continents could move around the planet, but researchers do now.

The Circum-Pacific Belt, also referred to as The Ring of Fire, is a path along the Pacific Ocean characterized by active volcanoes and frequent earthquakes.

Humanism: Humanism was one of the movements that started in Italy in fourteenth century. Italian universities were centres of legal studies. Francesco Petrarch is known as ‘Father of Humanism’. He suggested a shift from the study of law to the ancient Roman culture and texts. The term ‘humanism’ was first used by Roman lawyer and essayist Cicero. Humanists thought that they were restoring ‘true civilisation’ after centuries of darkness, for they believed that a ‘Dark Age’ had set in after the collapse of the Roman Empire. The period from the fifth to fourteenth centuries was the Middle Ages, and the Modern Age started from fifteenth century.

Factors which led to the beginning of Industrial Revolution in England were:

• The beginning of Renaissance and Reformation led to awakening among the people in Europe. Inventions made by the British scientists brought a revolution in the industries of Great Britain. Invention of the “Spinning Jenny’ by James Hargreaves in 1769 made the speed of spinning faster. Invention of ‘Water Frame’ by Richard Arkwright produced stronger and harder yarn than that of the Spinning Jenny and ushered in the factory system.
• England had a large colonial empire. She procured raw materials from colonies at cheaper rates for her industries. India was one of the countries from where she purchased raw materials like cotton at extremely cheap rates. She not only brought raw materials at cheap rates but also sold her manufactured goods in the colonial markets. Thus availability of markets led to the flourishing of industries in England.
• Several raw materials like iron and coal were available in England. Further, she was a supreme naval power. She was able to procure raw materials from other parts of the world by ships. Moderate climate of England helped in the development of textile industries.
• As England began to reap huge benefits from the international trade, industries in England began to expand bringing about increase in production of goods and materials.  Napoleonic Wars had damaged the trade and industry of the continental countries. But since these wars were never fought in Britain, the long period of peace prevailed which led to the development of industrial production in England.
• The decline of feudalism resulted in large number of unemployed peasants. They came to cities in search of jobs and thus labourers were easily available for factories in England.
• The use of charcoal and tar enabled the construction of roads in many European countries. In 1804, locomotive engine was manufactured by George Stephenson. This improved transport system in England.
• The invention of steam engine by James Watt led to the beginning of the Industrial Revolution. In 1813, the railways ran with the help of steam.
• Many protestant artisans of Spain and France migrated to England for the fear of religious persecution in their own countries. The English government provided them with shelter and monetary help. Their skills helped in the development of industries in England.

The dimensional formula of current density is given by,

[M⁰ L^-2 T⁰ I¹]

Where,

• M = Mass
• I = Current
• L = Length
• T = Time

Current density = Current​/area = Q/ area×t​ = [M⁰L⁻²T⁻¹Q]

The dimensional formula of current density is given by,

[M⁰ L^-2 T⁰ I¹]

Where,

• M = Mass
• I = Current
• L = Length
• T = Time