Question 3) Short type answers: -
a) Define global warming.
b) What is wood charcoal?
Question 4) Answer in short:-
a)Why do diamonds shine?
b) Give four uses of carbon dioxide.
Answers
Answer:
The increase in the temperature of the earth’s atmosphere, caused by the increase of certain gases
During the heating of wood without access (or with limited access) of air in furnaces and retorts (sometimes in campfires as well). The high porosity of wood charcoal is responsible for its significant adsorption properties
Diamonds get their brilliance from three things: reflection, refraction and dispersion. ... Only a portion of the light hitting a diamond is reflected; the rest travels through it. As the light moves through the diamond, it is scattered and fractured, creating the sparkle that diamonds are known for.
Carbon dioxide is used as a refrigerant, in fire extinguishers, for inflating life rafts and life jackets, blasting coal, foaming rubber and plastics, promoting the growth of plants in greenhouses, immobilizing animals before slaughter, and in carbonated beverages.
Answer:
1. Define global warming.
= The increase in the temperature of the earth’s atmosphere, caused by the increase of certain gases is called global gases.
2. What is wood charcoal?
= Wood charcoal is mostly pure carbon, called char (the first syllable of charcoal), made by heating wood above 400° C in a low oxygen environment.
3. a)Why do diamonds shine?
= The brilliance of diamond is due to total internal reflection of light . As refractive index of diamond is high (2.42) , so that critical angle for diamond air interface is low (24.4 degree) . The diamond is cut so suitably that light entering the diamond from any face suffers multiple total internal reflections at the various faces , and remains within the diamond , Hence the diamond sparkles .
b) Give four uses of carbon dioxide.
= Carbon dioxide is used as:
- a refrigerant
- in fire extinguishers
- for inflating life rafts
- life jackets