The efficiency of any machine is given by:
efficiency = output obtained / input given
Substituting the values,
Efficiency = 105 / 150
Efficiency = 0.7
Converting this to a percentage, the efficiency of the hammer is 70%.
This is a fairly high efficiency, and this is due to the fact that the hammer is a simpler machine. The more complex a machine is, the greater are the losses in it due to friction, meaning there is a lower efficiency.
C3H8 + 5O2 -----> 3CO2 + 4H2O
This is propane burning in air or pure oxygen.
There are eight protons in an Oxygen's nucleus.
Answer:

Explanation:
Hello,
In this case, the enthalpy of combustion is understood as the energy released when one mole of fuel, in this case octene, is burned in the presence of oxygen and is computed with the enthalpies of formation of the fuel, carbon dioxide and water as shown below (oxygen is circumvented as it is a pure element):

Thus, since we already know the enthalpy of combustion of the fuel, for carbon and water we have -393.5 and -241.8 kJ/mol respectively, thereby, the enthalpy of combustion turns out:

Best regards.
Answer:
Only the number of neutrons change.