Bio-gas is the naturally produced fossil fuel, a by-product when bacteria decompose organic material under anaerobic conditions.
<h3><u>Explanation:</u></h3>
Organic matter particularly waste material is broken down by bacteria through fermentation in an environmental condition without any presence of oxygen. This process of decomposition leads to formation of bio-gas with "carbon dioxide and methane" in a 2:3 ratio. 
The above biological process is termed as bio-digestion or anaerobic digestion. Methane is flammable and thus bio-gas can be used as "energy source", a waste-to-energy transformation. The remaining decomposed matter is ideal as manure for plants due to its rich nutrient level. 
 
        
             
        
        
        
Answer:
the primary coil current produces a magnetic field, which changes as the current changes. the iron core increases the strength of the magnetic field. the changing magnetic field induces a changing potential difference (voltage) in the secondary coil.
 
        
             
        
        
        
Answer:
heat energy that is needed to raise tempeture
 
        
             
        
        
        
Yes, it did help to change the world climate 
for example by the Carbon Dioxide released from factories, Cars and even from respiration