In the formula xso4, the symbol x could represent the element

The answer is: Mg.

Sulfate anion (SO₄²⁻) has negative charge, so element X must be element with positive charge +2.

Magnesium (Mg) is metal from 2. group of Periodic table of elements, it lost two electrons to form magnesium cation (Mg²⁺).

Magnesium has atomic number 12, which means it has 12 protons and 12 electrons.

It lost two electrons to form magnesium cation (Mg²⁺) with stable electron configuration like closest noble gas neon (Ne) with 10 electrons.

Electron configuration of magnesium atom: ₁₂Mg 1s² 2s² 2p⁶ 3s².  

Electron configuration of magnesium ion: ₁₂Mg²⁺ 1s² 2s² 2p⁶.  

answer : (a) volume of the gas = 8.67 ×   l

                (b) second virial coefficient b = -1.21226 l/mole

solution :   given,     t = 300k

                                p = 20atm

                                z = 0.86

                                n = 8.2 mmoles = 8.2 × moles

                                r =   0.082 l atm/k/mol

        find,     (a) volume of gas   and (b) second virial coefficient b at 300k.

formula used :            

                          and            

(a)            

                    = \times 0.082\times 300}{20}[/tex]

                    = 8.67 ×   l

(b)      

                    = (0.00867-1) × 8.659

                    = - 8.5839 l/mole