Please help please with the answers

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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