Which of the following is the correct squence of atomic weights of given elements?

The number of electrons in the atom of an element X is 18 and the number of neutrons is 22. Which of the following is the correct representation of an atom of this element?

The number of electrons in the atom of an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of an atom of this element ?

Which of the following is // are correct expression for percent of given element ? [ m is mass of organic compound having given element ]

Which of the following is the correct squence of steps in the human life cycle? Choose the right option.

Mendeleff corrected the atomic weight of

Medeleeff corrected the atomic weight of :