मुझे रसायन समझना है, मैं क्या करू ? I want to understand chemistry, what should I do?

What do you understand by the term Green chemistry?

A teacher in her class tells students, 'First, do what I want you to do and then you may do what you want to do.' The situation demonstrates the use of which of the following?

A man is pushing a cart down a slope. Suddenly the cart starts moving faster and he wants to slow it down. What should he do?