A volume of 25cm3 of a carbonate solution of concentration 0.2mol dm-3 was neutralized by 20 cm3 of acid of concentration 0.5 mol dm-3. The mole ratio in which the reactants combine is?
1 mol of carbonate to 1 mol of acid

1 mol of carbonate to 2 mol of acid

2 mol carbonate to 1 mol of acid

3 mol of carbonate to 1 mol of acid