1) We know that rtp = number of moles × 24
= 0.25 × 24
= 6 dm³
Therefore the volume of 0.25 moles of gas at rtp is A) 6 dm³
3.1) Amount of Copper = 20 tonnes
Amount of pure copper from impure copper = 18 tonnes
Purity of copper = (Pure copper/ impure copper) × 100
= (18 / 20) × 100
= 18 × 5
= 90 %
Therefore the purity of copper is 90%
3.2) We know that oxygen has 8 protons and 8 neutrons, so the weight of oxygen molecule is 8 + 8 = 16 u
So, one mole of oxygen weighs 16 g, so 2 moles weigh 2 × 16 = 32 grams
But oxygen is diatomic so the weight is 32 × 2 = 64 grams
Therefore the weight of 2 moles of oxygen is 64 grams
3.3) Concentration of solution = Amount of solute/volume
= 4 moles/ 2 dm³
= 4 / 2
= 2 mol/dm³
Therefore the concentration of a solution containing 4 moles in 2 dm³ of solution is 2 mol/dm³
Happy to help :)
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Extremely sorry for the late answer