Which is the rope you never skip with?

What is next number in the pattern below:

131 517 192 123 ?

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?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

There are nine letters in the below-given diagram. You have to form a nine-letter word using these letters.

Manish and Manoj play 5 games of chess.
Both Manish and Manoj win the exact same number of games. There is no tie at all.

How?

Can you decipher the two rows to find the hidden word?

What is harder to catch the faster you run?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?