Multiple choice!

projectile height is modeled by the function h(t) = -16t^2 + v0t + h0 where t is the time in seconds, v0 is the initial vertical velocity, and h0 is the initial height.

a football is kicked from ground level with an initial vertical velocity of 48 ft/s. how long is the ball in the air?

a. 3 seconds
b. 10 seconds
c. 5 seconds
d. 8 seconds

d.7.5cm is your answer

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂