THOMSON's ATOMIC MODEL

The first simple model of an atom was proposed by J.J Thomson. According to Thomson, an atom is a positively charged uniform sphere of radius 10(minus 8) cm in which electrons are embedded in such a way that negative charge equals to positive charge. This model was also called plum-pudding model and water melon model.
This model was unable to explain the stability of an atom.

VOCABULARY(A)

ABDICATE : to give up power

SYNONYM : refusal from the power, renounce

ANTONYM : to gain power

The old king abdicated the throne.

VOCABULARY(A)

ABBREVIATE : to shorten

SYNONYM : to abridge, to curtail

ANTONYM : Lengthening, enhancing

The voluminous book was abbreviated for the convenience of the students.

DISTILLATION

This method is used for the purification of liquids which boils without decomposition and contain non-volatile impurities. e.g., pure water can be obtained from sea water by distillation, mixture of ether and toluene, benzene and aniline.

CRYSTALLISATION

This method is based the difference in the solubility of the various compound dissolved in a common solvent. e.g., a mixture of Potassium Nitrate and Sodium Chloride can be separated by this process.

PROPERTIES OF CATHODE RAYS

- Cathode rays always travel in straight line. Whenever an object is placed in the path of cathode rays, it casts a shadow on the walls opposite to the cathode.
- Cathode rays consist of material particles and produce mechanical effects.
- The beam of cathode rays are deflected towards the positively charged plate, hence the particles in the cathode rays carry negative charge.
- Cathode rays are also deflected from their path in magnetic field.
- Cathode rays penetrate the sheets of aluminium and other metals.
- The cathode rays produce X-rays when they strike metals with high melting point like tungsten.
- The cathode rays upon striking glass or certain other material cause them to glow.

DISTILLATION UNDER REDUCED PRESSURE

This process is used for those liquids which decomposes below their boiling point under reduced pressure, liquids boils at low temperature. Hence, the temperature for decomposition is not reached. Thus, this process is known as vacuum distillation e.g., glycerol can be separated by this method. It is also used for the concentration of sugar cane juice in sugar industry.

CHROMATOGRAPHY

Chromatography is a modern method proposed by Tswett in 1903. This method is based on the difference in the rates at which the components of a mixture are adsorbed on a suitable adsorbent. This method has been used to separate o and p- nitrophenol, to separate blue and red dyes, to separate plant pigments and other natural products.

DISCOVERY OF ELECTRON

Electron was discovered by J.J Thomson in 1897. When an electric charge at high voltage is passed through a gas at low pressure, a stream of rays is emitted from the cathode surface. These are called cathode rays.

DRAWBACKS OF DALTON ATOMIC THEORY

- It does not explain why atoms of different elements differ in their masses, valencies, etc.
- It does not explain the existence of isotopes and isobars.
- It does not explain the reason for difference in atoms of different elements.
- Discovery of electron, proton, and neutron discarded the individual nature of atom proposed by Dalton.

DALTON'S ATOMIC THEORY

The first definite theory about the structure of the matter was put forward by John Dalton in 1890.
Its main postulates are;
- All matter is made up of very small particles known as atoms.
- Atom neither be created nor be destroyed, it is the smallest particle that take part in a chemical reaction.
- All atoms of an element are alike and of different elements are different.
- Atoms of different elements have different masses and chemical properties.
- Atoms combine together in the ratio of small whole numbers.

HISTORY OF PLANNING IN INDIA

1.) First attempt to initiate economic planning in India was made by Sir M Vishveshvarayya, a noted engineer and politician, in 1934 through his book 'PLANNED ECONOMY FOR INDIA".

2.) In 1938, national planning commission was set up under the chairmanship of Jawahar lal nehru by the Indian National Congress. Its recommendations could not be implemented because of the beginning of the world war II and changes in the the Indian political situations.

3.) In 1944, 'Bombay Plan' was presented by 8 leading industrialists of Bombay. It was drafted by GD Birla and JRD Tata.

4.) In 1944, 'Gandhian Plan' was given by Sarojini Naidu Agarwal.

5.) In 1945, 'People's Plan' was given by MN Roy.

6.) In 1950, 'Sarvodaya Plan' was given by JP Narayan. A few points of this plan were accepted by the government.

BROAD SECTORS OF INDIAN ECONOMY

1. PRIMARY SECTOR
    Agriculture, forestry, fishing.

2. SECONDARY SECTOR
    Mining, Manufacturing, electricity gas and water supply, construction.

3. TERTIARY SECTOR
    Business, transport, telecommunication, banking, insurance, real estate, community and personnel services.

Important Facts about Some Metals (PART-II)

1. Chromium trioxide is known as chromic acid.
2. Nichrome wire is used in electric heaters[Ni, Cr, Fe].
3. Generally transition metals and their compounds are coloured.
4. Zeolite is used to remove hardness of water.
5. In cytochrome iron[Fe] is present.
6. Selenium metal is used in photo electric cell.
7. Gallium metal is liquid at room temperature.
8. Palladium metal is used in aeroplane.
9. Radium extracted from pitch blende.
10. World famous Eiffel Tower has steel and cement base.

CHARACTERISTICS OF INDIAN ECONOMY

Main characteristics of Indian Economy are;

1. AGRARIAN ECONOMY
    In an Agrarian economy, agriculture dominates in both the Gross National Product(GNP) and employment. More than half of India's working population is engaged in agriculture.

2. MIXED ECONOMY
    It is an economy, where both public and private sector co-exist. The nature of Indian economy is a mixed economy.The term was coined by J M KEYNES. India opted for 'Mixed economy' in the industrial policy of 1948.

3. DEVELOPING ECONOMY
    Following are the features which shows that India is developing economy:
    - Low per capita income
    - Heavy population pressure
    - Low capita per head
    - Unequal distribution of wealth/assets.

INDIAN ECONOMY

Economy is a framework that deals with four major decisions i.e, investments, production, consumption and expenditure.
Economics was defined by ADAM SMITH, "the father of economics, as the science relating to the laws of production, distribution and exchange".
Economics consists of two main branches micro-economics and macro-economics. The former deals with the forces of demand and supply, market types, labour supply and demand on a ceterus paribus approach. The later is concerned with aggregate output and income, inflation etc.

Important Facts about Some Metals (PART-I)

1. Zinc Phosphide is used for killing rats.
2. Wood furnitures are coated with zinc chloride to prevent termites.
3. Excess of copper in human beings causes disease called wilson.
4. Galvanised iron is coated with zinc.
5. Rusting of iron is a chemical change with increase the weight of iron.
6. Calcium Hydroxide is called Hydrolith.
7. Calcium hydride is used to prepare fire proof and waterproof clothes.
8. In flash bulbs, magnesium wire is kept in atmosphere of nitrogen gas.
9. Titanium is strategies metal because it is lighter than iron.
10. Group 1st elements are called alkali metals because its hydroxides are alkaline whereas group 2nd elements are called alkaline earth metals.

Vocabulary(A)

5. ABATE : to make or become less strong

SYNONYM : weakening, feeble
ANTONYM : strengthening, powerful

Emotions of a man abate him.  

Vocabulary(A)

4. ABASHED : Embarrassed

SYNONYM : guilt, feeling of shy
ANTONYM : cheerful, happy, joyous

He is abashed of his own mistakes.

Vocabulary(A)

3. ABASE : to humiliate

SYNONYM : degrade, disregard, dishonour
ANTONYM : regard, honour, respect, dignity

Abasing someone is immoral.