Which of the following statements is/are correct?

Molecular formula (or) molecular mass of a gasesous hydrocarbon can be determined even without knowing the percentage composition by eudiometry.

In Lassaigne’s test N and S both present in the organic compounds are converted into  ion.

${\mathrm{K}}_2{\mathrm{SO}}_4$ and ${\mathrm{CuSO}}_4$ are added in Kjeldahl’s method. ${\mathrm{K}}_2{\mathrm{SO}}_4$ acts as a catalyst while ${\mathrm{CuSO}}_4$ raises the boiling point of ${\mathrm{H}}_2{\mathrm{SO}}_4$ .

Layer test is used to distinguish  $C{\mathcal{l}}^{-}$ and  $B{r}^{-}$ ions.