Octane gas (C8H18) at 25oC, 1 atm enters a combustion chamber operating at steady state and burns with 120% of theoretical air entering at 25oC, 1 atm. The combustion products exit at 927oC and include only CO2, H2O, O2. If the mass flow rate of the fuel is 0.102 kg/s, determine the rate of heat transfer from the combustion chamber to the surroundings,

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant. 

In any atom of any element, you will find protons and neutrons in the nucleus of any atom