Using future tense after if
Is it correct to use future tense after If in this case;

I wonder if they'll go there tommorow.
or
I should say it this way; I wonder if they go there tommorow.

Thanks for help.

Question

Using future tense after if
Is it correct to use future tense after If in this case;

I wonder if they'll go there tommorow. 
or 
I should say it this way; I wonder if they go there tommorow.

Thanks for help.

Answer

If + will here is correct and natural.  This is not a first conditional expression (or any conditional).  The meaning of "if" here is the same as "whether".

Answer

It's quite common. "I wonder if they'll go there tommorow." sounds the most natural. The word "If" implies uncertainty and people are always uncertain of the future.

Answer

a polite way of asking someone for something such as information or their opinion, or asking them to do something.
I wondered if  You could possibly grant me some money?
I was wondering whether you would like to come to the park with me?
I wonder if you would do me a favor?

Answer

Simple answer is that #1 sounds correct and #2 sounds wrong :)