As shown in the figure below, a cow walks leftward 15\,\text m15m15, start text, m, end text to eat some flowers, then walks rightward 25\,\text m25m25, start text, m, end text to munch on some apples. The cow walks a total time of 510\,\text s510s510, start text, s, end text.

0.0196m/s

Explanation:

Since we are not ask what to calculate but we can calculate the cow's velocity.

Velocity = change in displacement/time

Change in displacement of the cow is +25-15 = 10m

Time taken = 510s

Velocity of the cow = 10/510

Velocity of the cow = 0.0196m/s

Hence the velocity of the cow is 0.0196m/s

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