How do simple machines make work easier?
a.
they add energy to the work.
b.
they increase the force needed to work.
c.
they reduce the speed of work.
d.
they increase the distance over which a force is applied.
c.?

 D.  They increase the distance over which a force is applied.

Explanation:

Simple machines are basic mechanical devices which make our work easier like lever, pulley, wheel and axle, inclined plane, wedge and screw. The magnitude of the force or direction is altered using a simple machine. They increase the distance over which a force is applied. They use mechanical advantage to increase the magnitude of the force.

  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

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