How many mg of calcium are present in a 500-mg tablet of calcium carbonate? ?

The molar mass of calcium carbonate is 100 mg/mmol, so the number of moles is:

moles CaCO3 = 500 mg / (100 mg/mmol) = 5 mmol

We see that there is 1 mole of Ca per 1 mole of CaCO3, therefore:

mass Ca = 5 mmol * (40.08 mg/mmol) = 200.22 mg

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.