A.Weak
B.concentrated
C.dilute
D.strong
Answer: A - Weak
Yes they are a pure substance
The significant figure is only 1 which is just the number 5. The zeros don't count.
Answer: In the reaction:
a) The reactants are: P
b) The products are: M and N
Explanation:
The given reaction equation is as follows.

Reactants are the species present on the left side on an arrow in a chemical reaction equation.
On the other hand, products are the species which are present on the right side of an arrow in a chemical reaction equation.
Hence, in the given reaction equation P is the reactant. Whereas M and N are the products.
Thus, we can conclude that in the reaction:
a) The reactants are: P
b) The products are: M and N
The answer is b. as a whole, the species is mutually beneficial to carry on each others traits and exist in the same ecosystem.