Correct Answer - C
Group 4 consist of elements-titanium (Z = 22), zirconium (Z = 40), hafnium (Z = 72) and rutherfordium (Z = 104). They are lustrous silvery metals with high melting points. These elements arer relatively electropositive but less so than those of Group 3. If heated, they react directly with most non-metals, particularly with oxygen, hydrogen (reversibly) and in case of Ti, with nitrogen also. With the exception of hydrofluoric acid, minerals acid have little effect unless hot. This unreactivity results from a thin impermeble oxide film which form which forms on the surface and prevents further attack. The best solvent for all metals is HF, because they form hexafluoro complexes.
`Ti + 6HF rarr H_(2) [TiF_(6)] + 2H_(2)`
The most stable oxidation state is `+4`. The lower oxidation states are not known for heaver elements. Even for Ti, they are easily oxidized to `+4` state.
