The ratio in which sodium and chlorine atoms combine to form 1 molecule of NaCl is
1:1
NaCl is an ionic compound in which the positively charged sodium ions are attracted by the surrounding negatively charged chlorine ions and the negatively charged chlorine ions are attracted by the surrounding positively charged sodium ions. Sodium and chlorine atom combine in the ratio similar to their valency. Both sodium and chlorine has valency 1. Therefore, they combine in the ratio of 1:1.