How are carbon and hydrogen of an organic compound estimated?

How are halogens of an organic compound estimated?

How oxygen present in an organic compound is estimated?

Property to be determined Method used for determination {:("(P) Estimation of carbon and hydrogen in an organic compound","(i) Lassaigne's test"),("(Q) Estimation of nitrogen in aniline","(ii) Carius method"),("(R ) Estimation of chlorine in carbon tetrachloride","(iii) Liebig's method"),("(S) detection of nitrogen, sulphur and halogens","(iv) Kjeldahl's method"):}

How is unsaturation in organic compounds tested ?

In the Duma's method for the estimation of nitrogen in an organic compound, nitrogen is determined in the form of

Explain the estimation of nitrogen of an organic compound by b) Kjeldahl's method