Answer:
The Answer is the bottom definition: Not clean or pure.
Explanation:
The prefix im- has a negative meaning, so impure means not pure.
 
        
             
        
        
        
Answer:
Which book is this, what's the plot?
 
        
             
        
        
        
The correct answer is "noun".
In this situation, attack is a noun because it denotes the act of attacking. It doesn't denote attacking itself in which case it would be a verb.