Mass of copper atom is
and density of copper atom is
.
First calculate the volume from density and mass as follows:

Now, convert
to
,

Thus,

Now,

Thus,

or,
m=8.92 g
The molar mass of copper is 63.54 g/mol thus, number of moles can be calculated as:

Now, in 1 mol of Cu there are
atoms, number of atoms in 0.1403 mol will be:

Answer:
The angular speed after 6s is
.
Explanation:
The equation

relates the moment of inertia
of a rigid body, and its angular acceleration
, with the force applied
at a distance
from the axis of rotation.
In our case, the force applied is
, at a distance
, to a ring with the moment of inertia of
; therefore, the angular acceleration is



Therefore, the angular speed
which is

after 6 seconds is


Hi!
The weight force is given by: F = mg (mass x gravity)
Then, we have:
29 = m * 9.8
29/9.8 = m
m = 2.95 kg
;)
B is the correct answer on this