Afictitious element x is composed of 10.0 percent of the isotope 55x, 20.0 percent of the isotope 56x, and 70.0 percent of the isotope 57x. calculate the weighted atomic mass of element x to the nearest tenth.

The weighted atomic mass of element X = 0.1*55 + 0.2*56 + 0.7*57 = 56.6 g/mol. 

56.6

Explanation:

Assuming here that we have 100 atoms of each element. The percentage tells us that we have 10 atoms of the 55 isotope, 20 of the 56, and 70 of the 57.  

So the total is 10*55 + 20*56 + 70*57 = 5,660. And to get the average, we just divide by the total number of atoms (100).  

Atomic mass = 5660/100 = 56.6  

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.