Number of moles is defined as the ratio of given mass in g to the molar mass.
The mathematical formula is:
Number of moles = 
(1)
Number of zinc atoms is equal to 
, by Avogadro number, number of moles can be calculated.
As, 1 mol=
atoms, hence,
= 0.2822 mol
Now, from formula (1), calculate mass in g (molar mass of zinc = 65.4 g/mol)
0.2822 mol = 
mass in g = 
= 18.45588 g
Thus, by rounding off the above number, it will come near about 19 g approximately.
Hence, option (C) is the correct answer.
Answer:
3.91x10²³ atoms of lead
Explanation:
In chemistry, a mole of a substance is defined as 6.022x10²³ particles that could be atoms, molecules, ions, etc.
As you can see, in the problem, you have 0.650moles of lead in a fishing line sinker, the present atoms are:
=<em> 3.91x10²³ atoms of lead</em>
True, it would slow down.
t1/2 = ln 2 / λ = 0.693 / λ
Where t1/2 is the half life of the element and λ is decay constant.
32 = 0.693 / λ
λ = 0.693 / 32 (1)
Nt = Nο eΛ(-λt) (2)
Where Nt is atoms at t time, λ is decay constant and t is the time taken.
t = 1.9 hours = 1.9 x 60 min
From (1) and (2),
Nt = Nο e⁻Λ(0.693/32)*1.9*60
Nt = 0.085Nο
Percentage = (Nt/Nο) x 100%
= (0.085Nο/Nο) x 100%
= 8.5%
Hence, Percentage of remaining atoms with the original sample is 8.5%
