Answer:
90 minutes long
1 hour, 30 minutes
Explanation:
The science class begun 1:30pm and ends 3:00pm
An hour is 60minutes.
Between 1:30pm and 2:00pm is 30minutes.
And from 2:00pm to 3:00pm is an hour, that is 60minutes
We therefore have 30minutes+60 minutes=90 minutes long.
We can also say an hour, 30 minutes