If you add 500 kj of heat to 500 g of water at 50.0°c, how much water is left in the container? the latent heat of vaporization of water is 2.26 ×103 j/g and its specific heat is is 4.190 j/(g∙k)

First, we will get the heat required to raise the 500 g of water from 50°C to 100°C = m*C*ΔT 

when m is the mass = 500 g 

and C is the specific heat capacity of water = 4.19

ΔT change in temperature = 50 °C

by substitution:

q = 0.5 Kg * 4.19 * 50°C

   =104.75 KJ

∴ heat left to boil the water= 500KJ - 104.75KJ = 395 KJ

the heat required to boil water from 100°C to steam = mass *latent heat of vaporization

  395KJ     = M * 2.26 x 10^3

 Mass = 0.17Kg = 170 g

∴ water remain= 500 g - 170 = 330 g

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.