Combstion and flame

What is the SI unit of calorific value?

An increase in the average temperature of the earth’s atmosphere, especially a sustained increase that causes climatic changes, is termed as (a)   ""

The minimum temperature at which a particular substance burns in the presence of (a)   is called its ignition temperature..(in nb)

Which part of a flame does a goldsmith blow for melting gold and silver?

(a)  

   Refining is

• extracting petroleum gas       

• separation of various fractions of petroleum 

• heating of coal      

• sedimentation of fossil fuel

  In India, vast reserves of natural gas are found in

• Tripura        

• Rajasthan           

• Maharashtra

• All of these

Calculate the maximum theoretical temperature (t) attained when hydrogen is burnt in oxygen . The heat of combustion of hydrogen to water vapour is 57.8 Kcals. The specific heat of water vapour is [ 0.463 + 6.2x 10^-5t] t cals/g.

• 4580⁰ C                

• 4480⁰C

• 4308⁰C      

• 4380⁰C

Acid rain is caused by oxides of

• sulphur, nitrogen  

• sulphur, carbon     

• carbon, nitrogen    

• phosphorous, carbon

Define combustion....

• The process of burning a substance in the presence of oxygen to give out heat and light

• Combustion is a chemical process where something burns for our use

• When something burns in the presence of oxygen, it is called combustion

• When a particular object catches fire, in the presence of air (oxygen), it is called combustion

Match column 1 and column 2 and select the correct option from the given codes.

Column 1 Column2

P. Rusting i. Explosion

Q. Burning of paper ii. Spontaneous Combustion

R. Sodium iii. Rapid Combustion

S. Fire Crackers iv. Slow combustion

• P-ii, Q-iii, R-i, S-iv

• P-i, Q-iii, R-ii, S-iv

• P-iii, Q-iv, R-i, S-ii

• P-iv, Q-iii, R-ii, S-i