Answer:
Below are some patterns in the charge for elements in each group.
Group 1 elements : 1 valence electron and form ions with charge +1
Group 2 elements : 2 valence electrons and form ions with charge + 2
Group 3 elements : 3 valence electrons and form ions with charge + 3(there are some exceptions as well)
Elements in groups 4 and 5 are unpredictable also the D block elements consist of multiple oxidation states..
Group 6 elements : 6 valence electrons, form ions with charge -2
Group 7 elements: 7 valence electrons, form ions with charge -1
The octet rule is being followed, the elements form either ionic bond or covalent bond to fulfill it.
eg: when a K atom forms a K+ ion, the ion has the same electron configuration as the noble gas Ar (argon).
When an O atom gains 2 electrons to form the O²⁻ ion, the ion has the same electron configuration as the noble gas Ne (neon).
Note: Boron (B) is in Group 3 but doesn't form ions.
The valence part is referring to the outer most ring of electrons. Carbon only has four on the 'valence' or outer most ring helping it to form bonds with other things. I hope this helps!! Good Luck!!! :)
Formula to find the percent composition of an element in a compound is

.
Now enter the variables into the formula.

%
Round to 3 significant figures. 15.897% = 15.9%
The answer is 15.9% H
The answer to your question is A <span>4.184 J</span>
The mass of the solid product of the reaction is determined by weighing.