The focal length, like you said it's the distance between the FOCAL point and the mirror.
Hope this helps.... :)
And the answer is False,it does not have the same number with particles as the one mole of hydrogen.
C. Also just look up a chemical equation balancer calculator next time.
Adding fertilizer to stimulate the aquatic plant growth, and putting research and money into renewable energy
Answer: 
Explanation:-
Single replacement reaction is a chemical reaction in which more reactive element displaces the less reactive element from its salt solution.
As zinc is more reactive than copper, it could easily displace copper from its aqueous solution and thus leads to formation of zinc (II) sulfate and pure copper.
The chemical reaction can be represented as :

The phases are represented as (s) for solid sate, (l) for liquid state, (g) for gaseous state and (aq) for aqueous state.