Is it okay to say, "Email us if you have any question"?

Question

“CC” from the United States asked:

Is it acceptable to say, “Email us if you have any question" (with a singular noun), or is it only acceptable to say, “Email us if you have any questions” (with a plural noun)?

Answer

In an if-clause like this one, any can be used before a plural noun, like questions, or with a noncount noun, like information, as in these two examples:

• Call me if you have any questions. (questions is plural)
• Call me if you have any information. (information is noncount)

However, in an if-clause any cannot be used before a singular noun. In other words, it is not acceptable to say:

• Call me if you have any question. (question is singular)

Instead, use the article a rather than any, or use any with the plural noun, as in these examples:

• Call me if you have a question.
• Call me if you have any questions. 

I hope this helps.