How many atoms are present in 2 moles of calcium? (Atomic mass=40)

Dear student,

According to mole concept,
       1 mole = gram molar mass of the substance = 6.022 * 10²³ particles of the substance

Hence 1 mole of Ca = 40 g of Ca = 6.022 * 10²³ atoms of Ca

​​​​​Therefore 2 mole Ca = (6.022 * 10²³ )*2 atoms of Ca = 12.044 * 10²³ atoms of Ca

Regards