A student mixes 5.00 mL of 0.0020 M Fe(NO3)3 with 3.00 mL of 0.0020 M KSCN solution and 2.00 mL water at a certain temperature. He places a sample of the resulting solution in a spectrometer, and measures the transmittance as 23% at 447 nm. What are the initial concentrations of [Fe3 ] and [SCN-]

[Fe⁺³] = 0.0010 M

[SCN⁻] = 0.0006 M

Explanation:

First we calculate how many moles of Fe⁺³ and SCN⁻ were added, using the given volumes and concentrations:

Fe⁺³ ⇒ 5.00 mL * 0.0020 M = 0.010 mmol Fe⁺³SCN⁻ ⇒ 3.00 mL * 0.0020 M = 0.006 mmol SCN⁻

Now we can calculate the initial concentrations, after calculating the new volume of the solution:

New volume = 5.00 mL + 3.00 mL + 2.00 mL = 10.00 mL[Fe⁺³] = 0.010 mmol / 10.00 mL = 0.0010 M[SCN⁻] = 0.006 mmol / 10.00 mL = 0.0006 M

Your answer is a just took the test

Answer : option a) 84explanation :

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.