CBSE Class 9 Answered

Mole concept:

1 mole of a substance is equal to its atomic mass or molecular mass expressed in grams.

The atomic mass expressed in grams is the gram atomic mass.

The molecular mass expressed in grams is the gram molecular mass.

For example

Therefore, 23 grams of sodium is equal to one mole of sodium atoms.

                                                                              = 2 × 16 = 32 g

So, 32 grams of oxygen is equal to one mole of oxygen molecules.

1 mole (of anything) = 6.022 × 10²³ in number