How would you convert acetylene to acetone?

How will you convert: (a) acetylene to acetaldehyde (b) ethylene to acetylene (c) isopropylbromide to n-propylbromide (d) acetic acid to methane ?

How will you convert acetylene to but-1-ene?

How will you convert : (ii) acetone to acetone cyanohydrin

How will you convert benzene into ?