Neither sentence is completely correct, but they can be improved. Here's the corrected version: 1. When you come home, bring me one chocolate bar and a bag of chips, please. 2. When you come, bring me one chocolate bar and a bag of chips, please. Notes: * "Home" is optional, depending on the context. * "A chips" is incorrect because "chips" is plural, so you need to specify "a bag of chips."

Both can be used. However it needs to be either 'a bag of chips' or 'some chips'.