Find the Empirical formula for 0.765g Cr, 0.235g O

CrO

Explanation:

0.765g Cr

0.235g O

O = 16g/mol

Cr = 52g/mol

O     2-

Cr  2+, 3+, 6+

0.765 + 0.235 = 1

so 76.5% Cr

23.5% O

76.5/52 = 1.47/1.47 = 1

23.5/16 = 1.47/1.47 = 1

CrO

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.