What do you see in the given picture?

Two guards were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?"

How did he know his companion was smiling?

John is 45 years older than his son Jacob. If you find similarities between their ages, both of their ages contain prime numbers as the digits. Also, John's age is the reverse of Jacob's age.

Can you find their ages?

John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?

I am lying and I always lie. Tell me whether I am lying or telling the truth.

Which number should replace the question mark?

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

Count the squares in the matchstick puzzle below?