What concept in dalton’s atomic theory has been modified? a. all matter is composed of atoms. b. atoms of different elements have different properties and masses. c. atoms can combine in chemical reactions. d. atoms cannot be divided.

(D) Atoms cannot be divided

Explanation: It wasn't until around 2,000 years later, in the early 1800s, when John Dalton came along and disproved Aristotle. Dalton went on to say that matter is made up of tiny particles, called atoms, that cannot be divided into smaller pieces and cannot be destroyed.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.