Answer:
Q2->They all form acids when combined with hydrogen. They are all fairly toxic. They readily combine with metals to form salts.
Q3->Because their outermost orbit is complete.  In Mendeleev's original periodic table there was no place reserved for noble gas.  They were discovered in end of 19th century.  So Mendeleev created zero group without disturbing original periodic table.
Explanation:
 
        
             
        
        
        
Black the creamer makes it look white along with the side of the cup that it is in and the lighting and your phones picture could also make it different than it looks
        
                    
             
        
        
        
The Algae. Unless you want to get into the microorganisms that contribute to the algae's growth.
        
             
        
        
        
It’s C new seeds
Hope this helps
        
             
        
        
        
Humans have higher brain functions