Answer:
A chemical element is a type of atom with the same number of protons in their <u>atomic</u> nuclei. 
Explanation:
For an example, the atomic number of Chlorine is 17, and there is 17 protons in Chlorine.
If you have any questions feel free to ask in the comments.
 
        
                    
             
        
        
        
Because they have not been distrubed
        
             
        
        
        
Punnet squares are a useful tool for predicting what the offspring will look like when mating plants or animals. Reginald Crundall Punnett, a mathematician, came up with these in 1905, long after Mendel's experiments. Let's take a look at how Punnet squares work using the yellow and green peas example from im not sure about the tree by three thing but maybe this will help :)
 
        
             
        
        
        
Answer:
Land can become polluted by household garbage and by industrial waste. In 2014, Americans produced about 258 million tons of solid waste, according to the U.S. Environmental Protection Agency. A little over half of the waste — 136 million tons— was gathered in landfills. Only about 34% was recycled or composted. 
Hope this helps and I hope its correct.