Dating Techniques

Study for civil services :-
 Radiocarbon dating is used to determine the age of carbon bearing materials like wood, animal fossils etc.

 Uranium dating is used to determine the age of Earth, minerals and rocks.


 Battery is a device, used to convert chemical energy into electrical energy and is of two types (i) Primary batteries (non-rechargeable) act as galvanic cell, e.g., dry cell, mercury cell etc.

(ii) Secondary Batteries: (rechargeable) Act as galvanic as well as voltaic cell

E.g., lead storage battery, nickel cadmium battery etc.

Study for civil services :-

 The oxidative deterioration of a metal surface by the action of environment is called corrosion, an electrochemical process.

 When iron exposed in to air, iron surface turns brown due to the formation of hydrated ferric oxide (Fe203.xH20) which is also called rust,

 Silver – Surface turns black due to the formation of silver sulphide (Ag2S)

Renewable Non-renewable Natural Resources

 Renewable resources are available in large excess ( get renewed with time ) , i.e., never ends, e.g, air, sunlight etc.

Study for civil services :-
 Non-renewable resources are available in limited quantity and end, if used excessively, after a limited period of time. e.g., mineral, coal, petroleum, natural gas etc.

Fuels  The substance, which produce heat and light on combustion are called fuels.

 A strong foul smelling substance, called ethyl mercaptan is added to LPG to detect its leakage as LPG is an odourless gas.

Some important fuels and their compositions
1.Water Gas
Carbon monoxide (co) + hydrogen(h2)
Produced By passing stream over red hot coke

Study for civil services :-
2.Producer Gas
Carbon monoxide (CO) + Nitrogen (N2)
Produced By passing insufficient air over red hot coke

3.Coal Gas
Hydrogen + methane + Ethylene + Acetyene + CO +Nitrogen
Produced By fractional distillation

4. Natural Gas
Methane(83%) + Ethane
Produced From petroleum

5.Liquefied Petroleum Gas (LPG)
Propane and Butane + Others present in traces or small fractions are Iso-butane, butylene, n-butane, propylene etc.

Study for civil services :-
Produced From petroleum (LPG is normally odorless, small amounts of a pungent gas such as ethanethiol (also known as ethyl mercaptan )

6.Compressed Natural Gas (CNG)
Methane (CH4) 95% (methane stored at high pressure) can be used in place of gasoline (petrol), Diesel fuel and propane/LPG )
Produced From petroleum

7.Biogas or Gobar Gas
Methane (CH4) + Carbon dioxide (CO2) + Hydrogen (H2)+ Nitrogen (N2)
Produced From organic wastes