[statistics] CHI-SQUARED critical value

Yes, see the attached Wiki page about Chi-square.

If you scroll down to Characterization paragraph, you can see its cumulative distribution function formula.

Other software like Excel and SPSS has this functino already built in, you can call them out but apecifying the degree of freedom and alpha.

P-value is always be used to testing the hypothesis.

Using P-value and Alpha to compare together, then you can draw the conclusion out for the hypothesis.

P-value is small enough say <0.00001 when setting the alpha .05, then the null hypothesis is rejected.