what does the below rebus means?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

What number comes next in the series?

5 15 5 18 5 24 14 20 _

Which flower has two lips?

There is a place where if I stand up straight, I will still be considered sideways.

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

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

In a town, there are over 100 flats.
Flat-1 is named first flat.
Flat-2 is named second flat.
Flat-3 is named third flat.

A visitors 'Victor' decides to walk through all the flats, he finds all the flats except flat-62.
Victor later founds that the local of the town have given it another name.

What is the name of the Flat?

If you drop a 15 kg iron bar and a 5 kg bag of cotton from a height of 50 meters which will reach the ground first?

what does the below math rebus puzzle mean?