Do 1 mole of Na and `O_2` have same mass?

Do 1 mole of sodium and calcium have different number of atoms ?

Mass and weights have same units.

The formula of an acid is HXO_2 . The mass of 0.0242 moles of the acid is 1.657g . What is the atomic mass of X ?

Correct expression for density of an ideal gas mixture of two gases 1 and 2, where m_(1) and m_(2) are masses and n_(1) and n_(2) are moles and M_(1) and M_(2) are molar masses.

Calculate number of moles of Na2SO4 produced from 1 mole of NaOH when reacted with H2SO4.

Find the magnitude of two vectors veca and vecb , having the same magnitude and such that the angle between them is 60^o and their scalar product is 1/2 .

A vessel of uniform cross-section of length 500 cm as shown in figure is divided in two parts by a weightless and frictionless piston one part contains 5 moles of He(g) and other part 2 moles of H_(2)(g) and 4 moles of O_(2)(g) added at the same temperature and pressure in which reaction takes place finally vessel cooled to 300 K and 1 atm. What is the length of He compartment? (Assume volume of piston and vol. of H_(2)O(l) formed are negligible)

Calculate the mass of of 1 mole of each one of the following : Na2O2

"_2H_e^2 and "_1H^3 nuclei have the same mass number. Do they have the same binding energy?

Calculate the mass of of 1 mole of each one of the following : FeSO4.7H2O