(i) Define Avogadro’s number. Write its value.
(ii) Calculate the mass of 0.2 mole of oxygen gas.
(i) Avogadro’s number is the number of paticle(atoms , ions or molecules) constituted in 1 mole of substance
Value of Avogadro’s number = 6.022 x ${10}^{23}$
(ii) 1 mole oxygen gas consists = 32 g
0.2 moles of oxygen gas consists = 0.2 x 32 = 6.4 g