Which of the following equations demonstrates the law of conservation of mass? Mg + O2 ---> MgO
Ca + F2 --> CaF
Li + N3 --> Li3N
4Na + O2 ---> 2Na2O

Mg + O2 ---> MgO

Explanation:  V2O5 + CaS → CaO + V2S5. 5V2O5 + 5CaS → 10CaO + 5V2S5. 3V2O5 + 3CaS → 3CaO + 3V2S5.

weight of any object is given by

w = m*g

where m is mass of the object and g is the acceleration due to gravity.

for earth the value of g is 9.8 m/s^2 so

w=117.6 n m=12 g=?

117.6=12g => g=9.8 m/s^2

which is the force of gravity on earth.

yes the answer is total mass in unchanged   : )