There ( is - are ) a pen and a book on the table.

[abo.omar]

There ( is - are ) a pen and a book on the table.
The right answer is is but why not are?

 

[jutfrank]

When the first thing on a list is a singular noun phrase, it's better to use There is. If the first thing is a plural noun phrase, use There are.

There is a pen and two books on the table.

There are two books and a pen on the table.

 

[Tdol]

There is an effect called proximity- we tend to use what sounds right with the words near it, rather than simply following mathematical logic. There are a pen sounds odd to many speakers, regardless of what comes next.

 

[Roman55]

And if you change the word order you must use are regardless of proximity.
A pen and a book are on the table.

 

[Tdol]

I agree that 'There is' is OK, but I would not say that 'There are' was incorrect.

I agree with that.