Answer:
Hey!
Your answer is element A
Explanation:
Using the graph, the element A's emission of radioactive particles ends approximately after 6 years...
A HALF-LIFE IS "HALF" OF THAT TIME PERIOD!
So if the radiation goes for 6 years the half-life is 6 divided by two which gives you 3 years!
The rest however have a longer half-life...
Because they all end at 14 yrs so their half-life in 7 years!
HOPE THIS HELPS!!
When Cr+3 + 3e- → Cr(s)
So according to the charge formula:
charge Q = I * t
when we have I (the current) = 7.4 a
and t (the time in seconds) = 1.85d * 24h * 60 min*60sec= 159840 sec
by substitution:
Q = 7.4 a * 159840 sec = 1182816 C
now to get the mass we have to use Faraday constant which is:
F = e NA
= 1.602 x 10^-19 * 6.022 x 10^23
= 96485 C mol^-1
when e is the electron charge & NA Avogadro's number for the charge in on mol
and as we can see from the equation Cu3+ reacts with 3 electrons so,
the mass of Cr(s) = Q* (1mole-/F) * (1molCr / 3 mol e-)
= 1182816 * (1/96485) * (1/3)
= 4.1 g