How many of the following statements are correct
1) Sandmeyer reaction is used in the preparation of fluorobenzene
2) Iodobenzene is prepared by simply shaking of diazonium salt with aqueous $KI$   solution.
3) Chloroform is slowly oxidized by air in the presence of light to phosgene gas.
4) Freon  $12\left(CC{l}_2{F}_2\right)$  is manufactured from tetrachloromethane by using swarts reaction