The mass of 1.63 x 10^21 silicon atoms is:?

Question

A. 2.71 x 10^-23 g.
B. 4.58 x 10^22 g.
C. 28.08 g.
D. 1.04 x 10^4 g.
E. 7.60 x 10^-2 g.

Answer 1

well, lets think about this

avagodro's number is the number of atoms in a mole and =
6.02 x 10^23

so, if we divide the number of atoms in the problem by the number of atoms in a mole, we will get moles of the atom

I think you get .0027 moles.
a quick glance at the periodic table of the elements will give you the molecular weight for silicon
28.0855 grams/mole

multiply and you get .076 or in sci notation, 7.6 x 10^-2

assuming I punched the calculator correctly, it looks like "E".

Answer 2

i agree with the person above me, the answer is E.

(1.63 x 10^21) * (6.022 x 10^23)^-1 * 28.08 = 7.60 x 10^-2 g

Answer 3

hi
i write the formulas here
not have calculator at the moment
first u will have to calculate no of moles by:
no of particle/avogardo number (6^23)
then using no of moles:
no of grams=no of moles*mass of one mole(relative atomic mass)
no of gram will be mass

Answer 4

E