Answer : The concentration of a solution with an absorbance of 0.420 is, 0.162 M
Explanation :
Using Beer-Lambert's law :

As per question, at constant path-length there is a direct relation between absorbance and concentration.

where,
A = absorbance of solution
C = concentration of solution
l = path length
= initial absorbance = 0.350
= final absorbance = 0.420
= initial concentration = 0.135 M
= final concentration = ?
Now put all the given value in the above relation, we get:


Thus, the concentration of a solution with an absorbance of 0.420 is, 0.162 M
<span>The answer is (D)-when the rate of the forward and reverse reactions are equal.</span>
Barium is an element that is primarily used in fireworks because of its distinct green colour while on the other hand, lead is used in electrical industries due to its unique properties. The ions of these elements can simply be identified when its insoluble salts get precipitated by any process.
Given the data from the question, the mass of arsenic that contains 1.23×10²⁰ atoms is 0.0153 g
<h3>Avogadro's hypothesis </h3>
6.02×10²³ atoms = 1 mole of arsenic
But
1 mole of arsenic = 75 g
Thus, we can say that:
6.02×10²³ atoms = 75 g of arsenic
<h3>How to determine the mass that contains 1.23×10²⁰ atoms</h3>
6.02×10²³ atoms = 75 g of arsenic
Therefore,
1.23×10²⁰ atoms = (1.23×10²⁰ × 75) / 6.02×10²³ atoms)
1.23×10²⁰ atoms = 0.0153 g of arsenic
Thus, 1.23×10²⁰ atoms is present in 0.0153 g of arsenic
Learn more about Avogadro's number:
brainly.com/question/26141731