Q23 of 203 Page 172

Calculate the number of moles in 12.044 × 1025 atoms of phosphorus.

6.022 × 10²³ atoms of phosphorus contains = 1 mole of phosphorus

So, 12.044 × 10²⁵ atoms of phosphorus will have = 12.044 × 10²⁵/6.022 × 10²³ = 200 moles

If 6 g of oxygen contains 1 mole of oxygen atoms, calculate the mass of one atom of oxygen.

How many atoms are there in 0.25 mole of hydrogen?

Calculate the number of moles present in a drop of chloroform (CHCl₃) weighing 0.0239 g. (Atomic masses: C = 12 u; H = 1 u; Cl = 35.5 u)

What is the mass of 5 moles of sodium carbonate (Na₂CO₃)?

(Atomic masses: Na = 23 u; C = 12 u; O = 16 u)