Caffeine has the molecular formula, C8H10N4O2. What is the percent composition of caffeine? Select one:
a) 33.33% C, 41.67% H, 16.67% N, and 8.33% O
b) 49.48% C, 5.19% H, 28.85% N, and 16.48% O
c) 25% C, 25% H, 25% N, 25% N, and 25% O
d) 27.92% C, 2.34% H, 32.56% N, and 37.19% O

b) 49.48% C, 5.19% H, 28.85% N, and 16.48% O

Explanation:

we find the mass for each element in one mole by multiplying the number of atoms in one molecule with the atomic mass

mC=8Ac=8*12=96g

mH=10AH=10*1=10g

mN=4AN=4*14=56g

mO=2AO=2*16=32g

by adding the masses together we find the molar mass of the molecule

M=mC+nH+mN+mO=96+10+56+32=194g/mole

we apply the rule of threes to find the percentage of each element

194g..96gC..10gH...56gN32gO

100gabcd

a=(100*96)/194=49.48%C

b=(100*10)/194=5.19%H

c=(100*56)/194=28.85%N

d=(100*32)/194=16.48%O

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.