If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

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.

Can you name three consecutive days without using the words Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

I’m tall when I’m young, and I’m short when I’m old. What am I?

A person was found dead on a big green land with no trees or buildings around. When the police arrived, they found a piece of rock lying next to him and the man was wearing clothes comprising of red, blue and yellow colours.

Can you tell who the person is and what was the cause of death?

Twice ten are six of us,

Six are but three of us,

Nine are but four of us;

What can we possibly be?

Would you know more of us?

Twelve are but six of us,

Five are but four, do you see?

What are we?

Manish has to secure 40% marks to pass his B.tech final exams.
He got just 40 marks and failed by 40-marks.

What is the maximum marks?