You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

The Puzzle: A girl, a boy, and a dog start walking down a road.

They start at the same time, from the same point, in the same direction.

The boy walks at 5 km/h, the girl at 6 km/h.

The dog runs from boy to girl and back again with a constant speed of 10 km/h. The dog does not slow down on the turn.
How far does the dog travel in 1 hour?

Lifeless eyes on my smiling face and watch your child's sleeping place. In their dreams they hold me tight. What am I?

Can you write down eight eights so that they add up to one thousand?

In four steps you need to move the word 'cold' From 'warm' by replacing one alphabet at a time such that every word formed at each step is acceptable in English Dictionary.

How many letters are in the alphabet?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

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

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

If an electric train is travelling south, then which way is the smoke going?