Asolid (a) is soluble in water to the extent of 1g per 100ml of water at room temperature and 10g per 100ml of water at the boiling point. how would you obtain pure a from a mixture of 10g of a,1g of impurity b (b has the same solubility in water as a) and 0.1g of impurity c (c is insoluble in water)? how many grams of pure a could be obtained after one recrystallization from water? how much pure a could be obtained, after one recrystallization, from a mixture of 10g of a,9g of b and 8g of c?

You are given a solid (A) that is soluble in water of 1g per 100ml of water at room temperature and 10g per 100ml of water at the boiling point. A is 90.1%.

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.