<span>More than 50</span>. There are more than 7000 chemicals in cigarette smoke, 250 of which are known to be detrimental to health and 69 chemicals are carcinogenic (can cause cancer).  Some of the carcinogenic chemicals in cigarette smoke are: Arsenic, Cadmium, Chromium, Formaldehyde and Nickel.
        
             
        
        
        
Answer:
Burning fossil fuels, and decomposition of dead organisms
Explanation:
 
        
             
        
        
        
Answer:
B. generating more nerve cells
Explanation:
Mitosis is the process whereby a cell divides into two genetically identical daughter cells. It is way through which living cells reproduce and multiply themselves. 
Hence, a nerve cell that do not typically undergo mitosis will be incapable of replicating/multiplying itself, hence, unable to generate more nerve cells.