How was the ball point pen invented?

Where was zero invented?

What is heavy water?

What is an atomic clock?

How do astronauts walk in space?

How do ice columns grow inside caves?

Why does the Mediterranean Sea appear blue and the Atlantic Ocean green?

How do we find direction in the sea?

How is weather forecast made?

What causes tides in the sea?

Are there mountains inside the sea?

What is Dead Sea?

How were the oceans formed?

What causes asthma?

Why do doctors examine the pulse?

What is a test-tube baby?

Why do dogs pant in summers?

Why do flowers ofraat ki rani bloom only at night?

Why do flies rub their legs together?

Why don’t leaves get heated in sunlight?