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

The first Republic Day of India was celebrated on $January\, 26, 1950$. What was the day of the week on that date?

The time taken by a clock between two single strikes is $2 \text{ seconds}$. What is the time taken to complete its strikes at $10$ o'clock? (in $\text{seconds}$)

On what date of $August, 1988$ did Friday fall?

At what time (in $minutes$) between $3$ o'clock and $4$ o'clock,will both the needles of a clock coincide with each other?

$A$ man who went out between $3$ and $4$ and returned between $8$ and $9$ found that the hands of the watch had exactly changed places. He returned at