They are examples of elements.
D is the answer. You cannot say that anyone is good at anything because it doesn't say that. And they were surveying the class of 2010
: E) 1000 = 10^3
6-3 = 3 ==> change is 10^3
HOPE I COULD HELP
I would say C. petroleum
A is wrong
B is impractical for "mainly used"
D thats too expensive
Answer:
CaCO3----------CaO+CO2
(40g+12g+16g×3) of CaCO3 produce (40g+16g) of CaO
100g of CaCO3 -----------------56g of CaO
20g of CaCO3-------------------x grams of CaO
x=(20g×56g)÷100g
x=1120gg÷100g
x=11.2g of CaO
Therefore, 11.2grams of CaO from 20grams of CaCO3
HOPE IT HELPED, PLEASE MARK BRAINLIEST