The amount of calcium in a 15.0-g sample was determined by converting the calcium to calcium oxalate, CaC2O4. The CaC2O4 weighed 40.3 g. What is the percent of calcium in the original sample

128 gram of CaC2O4 contains 40 gram of Calcium

40.3 gram of CaC2O4 cotnains = 40*40.3/128 = 12.59 gram of Calcium

out of 15 gram 12.59 gram is Calcaim that means around 50% of orginal sample has Calcium

d.) the average kinetic energy of the gas particles is greater in container b because its particles move faster.

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3