The closeness of a measurement to its true value is a measure of its accuracy. This term is the degree of which a certain measurement conforms to the correct value or the standard value. It is not the same with the term precision. Precision, on the other hand, is a measure used to characterize the closeness of the data measured.
<span>Each shell is composed of one or more subshells. The first K shell has one subshell, called ‘1s’; the L shell has two subshells, called ‘2s’ and ‘2p’; the third shell has ‘3s’, ‘3p’, and ‘3d’; and so on. A subshell is the set of states defined by the azimuthal quantum number, l, within a shell. The values l = 0, 1, 2, 3 correspond s, p, d and f subshells, respectively. The maximum number of electrons which can occupy a subshell is given by 2(2l + 1). This gives two electrons in an s subshell, six electrons in a p subshell, ten electrons in a d subshell and fourteen electrons in an f subshell.</span>
Like carbon-12 (C-12) and carbon-14 (C-14). C-12 is not radioactive but C-14 is radioactive. C-14 is radioactive isotope of C-12.
Answer : Note : The formula give in the question needs to be corrected , the formula of two chlorine atoms for every magnesium atom in the compound is
which is Magnesium Chloride.
Explanation : To write the formula of the compound we need to know the charge of the atoms or elements involved in the formula.
Charge of Mg is +2 and charge of Cl is -1 , to write the formula of the compound we always criss cross the charges. And also when we write the formula the total (or net) charge of the compound should be 0. Charge of Mg is +2 so to get the total(net) charge as 0 we need two Cl atoms with each -1 charge.
Mg = +2 , Cl = -1 , Cl = -1
2 Cl = -1 + (-1) = -2
Mg = +2 and 2 Cl = -2
+2 -2 = 0

So the formula for Magnesium Chloride is 
Answer:
<h3>The answer is 2.67 g/cm³</h3>
Explanation:
The density of a substance can be found by using the formula

From the question
mass of metal = 32 g
volume = 12 cm³
The density is

We have the final answer as
<h3>2.67 g/cm³</h3>
Hope this helps you