Suppose a group of volunteers is planning to build a park near a local lake. the lake is known to contain low levels of arsenic (). therefore, prior to starting construction, the group decides to measure the current level of arsenic in the lake. if a 14.3 cm314.3 cm3 sample of lake water is found to have 159.5 ng as,159.5 ng as, what is the concentration of arsenic in the sample in parts per billion (ppb), assuming that the density of the lake water is 1.00 g/cm3? 1.00 g/cm3?

The concentration of arsenic in the sample in parts per billion (ppb) is 11.1538 .

Explanation:

Density of the lake water =

Amount of arsenic in 14.3 of water = 159.5 ng =

Mass of the lake water:

Concentration in parts per billion:

parts per billion

The concentration of arsenic in the sample in parts per billion (ppb) is 11.1538.

answer: - 3.) the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

solution: - as per the rules, oxidation number of oxygen in its compounds is -2. the sum of oxidation numbers of all the elements of a molecule or compound is zero.

also, the oxidation number in elemental form is zero.

in no, the oxidation number of o is -2 so the oxidation number of n is +2 so that the sum is zero.

similarly, the oxidation number of c in co is +2 and o is -2.

on product side the oxidation number of n is 0 as it is in the elemental form() .

oxidation number of c in carbon dioxide is +4 as there are two oxygen in it and we know that each oxygen is -2.

so, oxidation number of n is changing from +2 to 0 and the oxidation number of c is changing from +2 to +4.

since nitrogen is reduced and hence no is acting as an oxidizing agent. carbon is oxidized and so co is acting as a reducing agent.

so, the right choice is number 3.)the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

it's c. elements are placed in rows based on how may valencies electrons have.