In a practical machine, the power output is smaller than the power input. considering the law of energy conservation, what can explain this occurrence? a. some of the energy is used to combat friction, and thus is transformed from mechanical energy to heat. b. some of the energy going into the machine is being created at a quicker rate than the energy coming out is being destroyed. c. some of the energy coming out of the machine is being destroyed. d. some of the energy going into the machine is being destroyed

The law of energy conservation states that energy cannot be created or destroyed, so choices B to D are immediately invalid. Choice A can explain this occurrence: A. Some of the energy is used to combat friction, and thus is transformed from mechanical energy to heat.

  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

b.

hope this : )