If a sample of coke is 95% carbon by mass, determine the mass of coke needed to react with 1.0 ton of copper (ii) oxide.. 2cuo(s)+c(> 2cu(s)+co2(g)

so thus far i have:
1 ton cuo = 907,185g cuo
907,185g cuo * (1mol cuo/79.545g cuo) = 11404 mols cuo (rounded) [11404.676]
11404 mols cuo * (1 mol c/2 mol cuo) = 5702 mols c (not rounded - no need)
5702 mols c * (12.0108g c/1 mol c) = 68485g c (rounded) [68485.5816]
68485g c * 0.95 = > > 65060.75g c< < (not rounded -exact)
[should i not have rounded? ]
here's what someone else gave

1.0 ton x (2000 lb / 1 ton) x (1 kg / 2.2 lb) x (1000 g / 1 kg) = 9.09x10^5 g cuo

9.09x10^5 g cuo x (1 mol cuo / 79.5 g cuo) x (1 mol c / 2 mol cuo) x (12g c / 1 mol c) x (1 g coke / 0.95 g c) = 7.2x10^4 g coke to two significant digits

the difference being that he used scientific notation for the 1 ton in

which is correct?

A3.37-mg sample of protein was chemically digested to convert its nitrogen into ammonia and then diluted to 100.0 ml. then 10.0 ml of this solution was placed in a 50-ml volumetric flask and treated with 5 ml of phenol solution plus 2 ml of sodium hypochlorite solution. the sample was diluted to 50.0 ml, and the absorbance at 625 nm was measured in a 1.00-cm cuvette and found to be 0.486. for reference, a standard solution was prepared from 10.0 mg of nh4cl (molar mass = 53.49 grams/mole) dissolved in 1.00 l of water. then 10.0 ml of this standard was placed in a 50-ml volumetric flask, treated in the same manner as the unknown, and the absorbance found to be 0.323. finally, a reagent blank was prepared using distilled water in place of unknown, it was treated in the same manner as the unknown, and the absorbance found to be 0.076. calculate the weight percent of nitrogen in the protein.

Which of these is an intensive property of a substance

Ethyl alcohol, also known as ethanol, has a density of 0.79 g/ml. what is the volume, in quarts, of 1.95 kg of this alcohol?