What does below chemistry rebus means?

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?

If I put in one canary per cage, I have one bird too many. If I put in two canaries per cage, I have one cage too many. How many cages and canaries do I have?

How many triangles can you find in this given picture?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

Which is the rope you never skip with?

Can you solve the below geography rebus by decoding the below rebus ?

2, 3, 5, 9, 17, _ What is the next number in the sequence?

Find out the missing number in the picture attached:

I know a nine-letter word having only one vowel.
Do you ?