What does below chemistry rebus means?

A mathematician couple was having a Frappuccino in Starbucks sitting opposite to each other. Suddenly the guy noticed the text written on the paper in front of them and exclaimed that it was wrong. The girl denied it and said it is appropriate. Both are correct. What is written on the paper?

What can you hold in your right hand, but never in your left hand?

Can you solve the below tricky visual equation?

I am a five-letter word under you,
Remove the first letter and I am above you,
Remove the second as well and I am around you.

Who am I?

John buys rice at Rs.60/kg from Britain and then sells them at Rs.5/kg in India. As a result of this, he becomes a millionaire. How come?

Can you complete the sequence?

192, 021, 222, 324, 252, 627, 2__, 9__?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

One day, I thought of ways that can be used for creating a palindrome. So I decided that I will turn into a larger number by adding the reversed digits to the original number and keep doing it till I finally obtained a palindrome.

I am not sure if this process will always result in a palindrome eventually but I was able to produce a four-digit palindrome. Can you guess my starting number?

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