X is the answer that we do not know yet!!:)
Answer:
M=Molarity
V=volume
change millilitre to litre
so:15ml=0.015 L
:38.5ml=0.0385 L
M1V1=M1V1
M1* 0.015 L= 0.15M*0.0385 L
M1=0.00385
A) Fe⁰ ----> Fe⁺³ +3e⁻ oxidation | *2
b) <u>Cu⁺² + 2e⁻ -----> Cu⁰ reduction |*3</u>
c) 2Fe⁰ +3Cu⁺² -----> 2Fe⁺³ + 2Cu⁰