What needs to happen for the equation ch4 + o2 → co2 + h2o to be balanced? a. nothing, the equation is already balanced. b. a coefficient of 2 must be added before the second reactant and the second product. c. a coefficient of 2 must be added before both products and reactants. d. a coefficient of 2 must be added before both products.

B. This is because the Hydrogen and Oxygen need balanced out.

Current-

C-1            |        C-1
H-4            |         H-2
O-2            |         O-3

Adding a coefficient of 2 before oxygen in the reactants and H2O in the products would balance this equation

CH4 + 2O2 → CO2 + 2H2O
C-1            |        C-1
H-4            |         H-4
O-4            |        O-4

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. 

The se-ci  bonds is more polar  than s-br bond