For a thermodynamic system containing 'x' chemical species, the maximum number of phases that can co-exist at equilibrium is

Answer: Option C

Since, phase rule is $$f\left(\text{degree of freedom}\right)=C-\varnothing +2$$
Where, $$C=$$  number of components, $$\varnothing =$$  number of phases,
$$\Rightarrow \varnothing =C-f+2$$
So for maximum phases $$f$$ should be minimum $$f$$ cant be negative since it denotes number of variables hence $$f=0$$
So, $$\varnothing =C+2$$
Given $$C=X\Rightarrow \varnothing =X+2$$