The table tells us that the larger the diameter the shorter the period of rotation is
It should be 0.25 M. Use the formula C1*V1=C2*V2, for those values, as it is right when it changed colour. Remember to change the if those are not the same (but in your case it is, so no need this time).
C1*V1=C2*V2
C1*27ml=0.55M*12.5ml
C1=(0.55M*12.5ml)/27ml = 0.25M
A combustion reaction is when a fuel, usually a hydrocarbon, reacts with excess oxygen to form carbon dioxide gas and water vapor.
A , write out and balance the reaction