I am white when I am dirty, and black when I am clean. What am I?

A patient was diagnosed with some ailment. He was given five different tablets to take at night at an interval of 15 minutes.

How long will it take the patient to consume all the five tablets?

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?

Analyze and find the missing item in the sequence:
16, 06, 68, 88, __, 98

The day before yesterday I was 25 and the next year I will be 28. This is true only one day in a year. What day is my birthday?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

Can you find the least possible number such that

If the number is divided by 3, it gives the remainder of 1;
If the number is divided by 4, it gives the remainder of 2;
If the number is divided by 5, it gives the remainder of 3;
If the number is divided by 6, it gives the remainder of 4.

Peter wakes up daily to pick up his cycle and crosses the border between Spain and France daily with a bag on his shoulder. He is investigated daily by the officials but they don't find anything suspicious.

If we tell you that he is smuggling something what would it be?

Consider all the numbers between 1 and 1 million. Among all these numbers, there is something very special about the number 8 and the number 2202. What is it?