Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

A river should be crossed by a father, a mother and their two sons and two daughters.
There are some rules that should be followed while crossing the river. There can be only two people in the raft while crossing. The daughters cannot be with their father unless there is the presence of the mother. The sons cannot be with their mothers unless the father is present. Unless the guard is on the board, the criminals cannot be with any of the family members. Only the adults like the father, the guard, and the mother knows to use the raft.

How will they cross the river?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

Can you find the ages of a son, father and grandfather based on the following facts?
The sum of the ages of grandfather, father and son is 140 years.
The age of the son in months is the same as the grandfather in years.
The age of the son in days is the same as the father in weeks.

The centre of the third figure is empty. What digit should fit inside?

What question can you never answer yes to?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

what does the below rebus mean?

Your last good ping-pong ball fell into a narrow metal pipe embedded one foot deep in concrete.
How can you get it out undamaged, if all the tools you have are your tennis paddle, shoe laces, and plastic water bottle, which does not fit into the pipe?

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