Caffeine in a sample of chocolate was measured five times, and the results were 1265 ppm caffeine with a standard deviation of 9 ppm. according to the product label, the chocolate contains 1250 ppm caffeine. are the experimental results statistically different from the label value at the 95% confidence level? a. yes, because tcalc < ttableb. yes, because tcalc > ttablec. no, because tcalc < ttabled. no, because tcalc > ttable

the answer is barium and copper bromide

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o