A student wishes to prepare 65.0 mL of 0.875 M HCl from 12.0 M HCl. What volume of the
12.0 M HCl should he/she start with?

4.74 mL

Explanation:

M1V1 = M2V2

12.0M*V1 = 0.875M*65.0 mL

V1 = 0.875M*65.0 mL/12.0M = 4.74 mL

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.