A divalent metal oxide contains 60% of metal. What is atomic weight of metal?
wt of metal= 60 g
wt of oxygen= (100-60) g= 40 g
Eq. wt. of metal = wt. of metal/ wt of oxygen* 8
= 12
As metal is divalent, At. wt= Eq. wt* valency= 12*2 = 24
Mass of 2 x 1021 number of atoms of an element is 0.4g. What is the mass of 0.5 mole of the element?
Given,
No. of atoms of an element = 2 x 1021
Mass of atoms of an element = 0.4g
According to the questions,
2 x 1021 atoms of an element has mass 0.4g
6.022 x 1023 atoms of element has mass = 120.44g
i.e. 1 mole of atom of an element has mass 120.44g
Hence, the mass of 0.5 mole of an elements is 0.5 x 120.44g = 60.22g