11.
How many times are the hands of a clock at right angle in a day?

12.
The angle between the minute hand and the hour hand of a clock when the time is 8:30, is:

13.
How many times in a day, are the hands of a clock in straight line but opposite in direction?

14.
At what time between 4 and 5 o'clock will the hands of a watch point in opposite directions?

15.
At what time between 9 and 10 o'clock will the hands of a watch be together?