It's called a compound because different elements are held together by a chemical bond.
It is very camouflaged this way it will survive longer then most other animals
ELECTRON CONFIGURATION
Highest occupied energy level of an element
equal to the period
for example, the highest occupied energy level of He is 1, Be is 2, Al is 3, Ca is 4, and Sn is 5
Complete Question
The complete question is shown on the first uploaded image
Answer:
The concentration of
that should used originally is 
Explanation:
From the question we are told that
The necessary elementary step is

The time taken for sixth of 0.5 M of reactant to react 
The time available is 
The desired concentration to remain
Let Z be the reactant , Y be the first product and X the second product
Generally the elementary rate law is mathematically as

Where k is the rate constant ,
is the concentration of Z
From the elementary rate law we see that the reaction is second order (This because the concentration of the reactant is raised to power 2 )
For second order reaction

Where
is the initial concentration of Z which a value of 
From the question we are told that it take 9 hours for the concentration of the reactant to become


So


=> 
For 




