Iodoform test is not given by :
HCHO
CH3CHO
CH3COCH3
C2H5OH
A.
HCHO
Iodoform test is given by those compounds which have -CO-CH3 gorup or on oxidation yields this group.
Formaldehyde does not have -CO-CH3 group. It does not give iodoform test.
Pure methane can be produced by
Wurtz reaction
Kolbe's electrolytic method
soda lime decarboxylation
reduction with H2