Explore topic-wise InterviewSolutions in Current Affairs.

1. c 

2. d 

3. e 

4. a 

5. b

(a) Oxidation

A concentrated solution of sodium chloride called BRINE is electrolysed to produce chlorine and hydrogen gases along with sodium hydroxide. This is a very important reaction to produce chlorine industrially.

1. In industries some chemical substances are used to alter the speed of a chemical reaction. These substances are called catalysts. 

2. For example, metallic iron is used as a catalyst in the manufacture of ammonia using Haber’s process. 

3. This ammonia is the basic material for the production of urea, an important fertilizer in agriculture. 

4. In Vanaspati ghee (dalda) preparation finely divided nickel is used as a catalyst.

5. Thus, speed of the certain reactions is influenced by the catalysts and such reactions are called catalytic reactions. 

6. Enzymes and yeasts are called biocatalysts.

Tarnishing of metal articles: 

This is because the iron metal comes into contact with water and oxygen, it undergoes a chemical reaction called Rusting. Shiny metal surfaces and other articles lose their shining appearance due to chemical reactions on the surface.

Corrosion :

1. Corrosion is the natural process by which a naturally pure metal converts into a more stable form of itself like hydroxide or oxide. 

2. It is an actual degradation of the metal as it renders the metal useless of its usual metallic character.

Rusting: 

1. Rusting is the specific name given to the corrosion of iron. Rust can be termed with the chemical formula of iron oxide with its general formula Fe₂O_3.

2. Iron when in contact in the air moisture or water, corrodes and forms rust.

Some of the chemical reactions can be achieved by the supply of heat only. These reactions are called thermo chemical reactions or thermolysis. In industries limestone rocks are heated to get quicklime (calcium oxide).

1. In industries some chemical substances are used to alter the speed of a chemical reaction. These substances are called catalysts. 

2. For example, metallic iron is used as a catalyst in the manufacture of ammonia using Haber’s process. 

3. This ammonia is the basic material for the production of urea, an important fertilizer in agriculture. 

4. In Vanaspati ghee (dalda) preparation finely divided nickel is used as a catalyst.

5. Thus, speed of the certain reactions is influenced by the catalysts and such reactions are called catalytic reactions. 

6. Enzymes and yeasts are called biocatalysts.

Chemical reaction requires a specific condition to occur. When chemical reactions take place there will be production of heat, light, sound, pressure etc.

Effects of chemical reactions are:

1. Biological effects 

2. Environmental effects 

3. Production of heat, light, sound and pressure 

4. Evolution of gas, changes in colour and change in state.

Speed of the certain reactions is influenced by the catalyst and such reactions are called catalytic reactions.

Chemical reactions accompanying evolution of heat are called exothermic reactions whereas reactions involving absorbtion of heat are called endothermic reactions.

(iii) p₁ < p₂ < p₃ < p₄ 

(iii) polarisability of interacting particles 

(a) Excess of carbon dioxide increases the temperature of the earth. Due to rise in temperature ice in the polar regions may melt causing floods in coastal regions island.

(b) In both of these fire extinguishers, the solutions are prepared in water, which conducts electricity. As a result, an electric shock might result, which might lead to shortcircuiting and another fire.

(c) Solid carbon dioxide serves as a coolant and refrigeration for preserving food articles.

Ethanol is a good solvent so it is used in making medicines such as tincture iodine, cough syrups and many tonics. Ethanol is also used in making alcoholic drinks. 

Harmful effects: Intake of small amount of ethanol leads to drunkenness. Intake of even small amount of ethanol can be lethal. Long-term use or consumption can lead to severe health problems.

Fire Extinguisher— Fire extinguishers are a device in which carbon dioxide is produced in different forms for use as the extinguishing agent. It is a modem type of fire extinguisher in which liquid carbon dioxide is stored in a steel cylinder under pressure. Soda-acid and foam types of extinguisher cannot be used for extinguishing the fire as they prepared in water, which conducts electricity and there can be short-circuiting, causing another fire.

Green house effect— The trapping of the earth’s radiated energy by carbon dioxide present in air, so as to keep the earth warm, is called ‘green house effect’. A greenhouse is beneficial because this principle is applied to grow plants in colder regions. 

Carbon dioxide increases the temperature of the atmosphere. Due to rise in temperature; ice in the polar regions may melt, causing floods. So it is harmful for life on earth.

(C) carbon dioxide only

As global warming will cause an unbalanced ecological system, serious efforts should be made to balance the percentage of carbon dioxide in the atmosphere. 

Some of these steps are:

• Growing more trees and plants.

• Using smokeless sources of energy like solar energy, biogas, etc.

• Using filters in the chimneys of factories and power houses.

all of the above

coal is an amorphous form of carbon.

Comparison of the Properties of Diamond and Graphite

1. By planting more trees.

2. By combustion of fuels

3. By decay of dead animals, plants and plants products.

Anthracite is a superior type of coal.

Amorphous Forms of Carbon

i) Coal

ii) Wood Charcoal

ii) Animal Charcoal

ii) Sugar Charcoal

Gas Carbon and Petroleum Coke

Carbon scraped that is from the walls of the retort used for the destructive distillation of coal in called gas carbon. During refining of crude petroleum, petroleum coke is deposited on the walls of the distillation tower.

Both, gas carbon and petroleum coke are used for making electrodes in dry cells and are good conductors of electricity.

Ethyne when burnt in the presence of oxygen gives enough heat that can be used for welding. 

Whereas if it is burnt in air which contains nitrogen, CO₂ and other inactive gaseous contents, sufficient oxygen is not available for burning ethyne to give the required heat.

A function of activated charcoal:

• It is used as a catalyst in various chemical reactions e.g. reaction of hydrogen with chlorine.

• It is used to separate a mixture of noble gases, like helium, argon, neon, krypton etc.

• It adsorbs different gases at different temperatures.

(a) Charcoal is formed when charcoal is burnt in a limited supply of air.

(b) Coal is an amorphous form of carbon.

(c) Peat is the most inferior form of coal.

(d) Wood charcoal is a bad conductor of heat and electricity.

(e) lampblack is used in making black shoe polish.

(a) Carbon monoxide is formed when carbon is burnt in a limited supply of air or oxygen.

(b) Carbon monoxide bums in air with a pale blue flame to form carbon dioxide.

(c) Carbon monoxide is a products of incomplete combustion.

(d) A mixture of 95% oxygen and 5% carbon dioxide is called carbogen

(e) Carbon dioxide is used as a reducing agent in the extraction of pure metals from their corresponding ores.

(a) Formation of coal:- The formation of coal took millions of years. Coal was formed by the bacterial decomposition of ancient vegetable matter hurried under successive layers of the earth. Under in action of high temperature and pressure, and in the absence of air, the decayed vegetable matter converted into coal.

(b) Types of Coal:

1. Peat: It is light brown in colour and contains only 50 – 60% carbon. It is the most inferior form of coal.

2. Lignite: it contains more than 60% carbon. It is brown in color and harder than peat.

3. Bituminous: It has 90%, 80%, 70 – 75% carbon contents. Bituminous coal is the most common variety of coal and used as household coal.

4. Anthracite: It is the purest variety of coal. Its carbon contents vary between 92 – 98%. It is hard, dense and black, difficult to ignite.

Uses of coal:

1. Coal is used as both domestic and industrial fuel.

2. It is used to prepare coke, coal gas and coal tar.

Carbon Black

When natural gas is burned in limited supply of air, the resulting soot is deposited on the underside of a revolving disc. This is carbon black and it is then scraped off and filled in bags. It differs from lamp black in being not so greasy. Carbon black is added to the rubber mix used for making automobile tyres, and has replaced the use of lampblack for a number of purposes.

(a) Wood charcoal is formed when wood is burnt in a limited supply of air.

(b) Bone charcoal, bone oil and organic compound pyridine.

(c) Carbon dioxide.

(d) Artificial diamond.

Carbon possesses a unique property of combining with other carbon atoms to form long chains. This property is called catenation. The chains can be straight, branched or closed.

Gas carbon is produced by the destructive distillation of coal or heating of hydrocarbons at high temperature. During this process decomposition takes place and carbon particles are collected to form gas carbon.

(a) Uses of coal

• It is used as both a domestic and an industrial fuel.

• It is used to prepare coke, coal gas and coal tar.

(b) Uses of coke

• Coke is used as a smokeless fuel, in smelting furnaces.

• It is used in the manufacturing of water and producer gas.

(c) Uses of wood charcoal:

• Wood charcoal is used as a fuel.

• It is an important constituent of gunpowder.

(d) Sugar charcoal:

• Sugar charcoal is mostly used as a reducing agent.

• It is used to decolorize colored solutions.

(e) Bone charcoal:

• It is extensively used to decolorize cane-sugar in the process of manufacturing sugar.

• It is also used in the manufacture of a large number of phosphorous compounds.

(f) Uses of lampblack:

• It is used in making black shoe polish.

• It is used in the manufacture of tires and gunpowder.

Lamp Black

Lamp black is manufactured when tar and vegetable oils (rich in carbon) are burnt in an insufficient supply of air and the resulting soot is deposited on wet blankets hung in a room. Lamp black is a velvety black powder. It is used in the manufacture of India ink, printer's ink, black paint and varnishes and carbon papers.

Diamond: It is used in making jewelry items.

Graphite: It is used to make pencil lead and electrodes.

Coke: It is used as an industrial and household fuel.

Bone charcoal: It is used as a decolorizing agent in sugar cane industries.

The purest form of the amorphous carbon is sugar charcoal

 (i) Water spreads to recharge wells.

(ii) Provides moisture to vegetation over a wide area

(iii) Does not provide breeding ground to mosquitoes.

(iv} Protected from contamination.

Fuel gases like water gas and producer gas are manufactured from coke.

Atoms may or may not have an independent existence. Molecules have an independent existence.

(a) The molecules of matter are always in motion and attract each other with a force called the intermolecular force of attraction due to which they are held together.

(b) The molecules can move only when there are gaps or space between them, this space is called intermolecular space.

Mass is the “quantity of matter” and weight is “the force with which the earth pulls a body towards itself’. The mass of a body does not change but its weight changes from place to place.

Weight of body on moon = 1/6th of its weight on earth. 

∴ Body will weight 1/6 of 6 = 1/6 x 6 = 1 N on moon 

Mass of a body does not change with change in gravity. So mass of a body will remain the same on moon.

Anything that has mass and occupies space is called matter.

(a) Melting.

(b) Intermolecular force of attraction.

(c) Solid.

(d) Sublimation.

(e) Condensation.

The amount of space occupied by a matter is called its volume.

Advantages of watershed management:

(i) mitigates drought and floods. 

(ii) increase the life of the dams and reservoirs downstream. 

(iii) increases the biomass production and thereby the income of the watershed community. 

(iv) helps in maintaining ecological balance by scientific conservation of soil and water.

high intermolecular force of attraction