Answer:
B. Burns cleaner than coal
 
        
             
        
        
        
The substance is pure depending on which atoms bond.
        
             
        
        
        
Answer:
If you double the speed of an object, the kinetic energy increases by four times. The word "kinetic" comes from the Greek word "kinesis" which means motion. Kinetic energy can be passed from one object to another in the form of a collision.
Explanation:
The kinetic energy is proportional to the square of the speed, so doubling the speed increases the kinetic energy by a factor of 4.
 
        
             
        
        
        
Answer:
The number of habitats falls below a critical level.
Explanation:
The possible reason for extinction is that the number of habitats falls below a critical level. This makes it impossible for organisms to survive. 
- A habitat is the dwelling place of living organism in an ecosystem. 
- The resources and other materials that ensures the survival of an organism are made available in the habitat. 
- When a habitat begins to thin out and can no longer support organisms, then extinction will ensue.