What is the working hours? or What are the working hours?

[yena]

Hi all,

I always thought 'what is the working hours?' is correct because we use a singular verb for periods of time.

But, I found the following sentence in a website that confused me again :

The hardest two hours of my life were spent trying to persuade ..., which was found in a website.


So, which one is correct? what is the working hours? or what are the working hours? Is the above sentence simply a mistake?

Please save me from this never-ending grammar confusion. Thanks.

[Tdol]

It should be 'are' because 'hours' is in the plural.