This equation indicates that the reaction gives off heat. what is this type of reaction called?
c3h8 +? o2 → 3co2 + 4h2o + heat
a.
synthesis reaction
b.
decomposition reaction
c.
endothermic reaction
d.
exothermic reaction

The correct answer is d.

C.because of the formula    c3h8 +? o2 → 3co2 + 4h2o + heat

Ais the

Ohm's law tells you that i = v/r where v is equivalent voltage and r is equivalent resistance of the circuit
since all circuits have the same voltage, your question is really asking which circuit has the lowest total resistance, since the lower the resistance, the higher the current
circuit a has a resistance of 5 ohms; circuit c is in series so has a resistance of 10 ohms; circuit b is in parallel and therefore has a resistance of 2.5 ohms (review your notes on adding resistances in parallel and series); therefore b has the highest current