What information is necessary to determine the atomic mass of the element chlorine?
(1) the atomic mass of each artificially produced isotope of chlorine, only
(2) the relative abundance of each naturally occurring isotope of chlorine, only
(3) the atomic mass and the relative abundance of each naturally occurring isotope of chlorine
(4) the atomic mass and the relative abundance of each naturally occurring and artificially produced isotope of chlorine

Answer is: (3) the atomic mass and the relative abundance of each naturally occurring isotope of chlorine.

m(³⁵Cl) = 34.97 amu; the average atomic mass of chlorine-35.  

m(³⁷Cl) = 36.97 amu; the average atomic massof chlorine-37.

ω(³⁵Cl) = 75.76% ÷ 100% = 0.7576; fractional abudance of chlorine-35.

ω(³⁷Cl) = 24.24% ÷ 100% = 0.2424; fractional abudance of chlorine-37.

m(Cl) = m(³⁵Cl) · ω(³⁵Cl) + m(³⁷Cl) · ω(³⁷Cl).  

m(Cl) = 34.97 amu · 0.7576 + 36.97 amu · 0.2424.  

m(Cl) = 35.4548 amu; average atomic mass of chlorine.

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

that's it!

if you need further assistance, let me know: )

~ trueboss72

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.