How would we perform the following chemical transformations?

These are possible reactions; there are many alternatives, and the proposed route might be highly impractical:

#1.# #"ethyl bromide "rarr" n-butane"#:

#C_2H_5Br + Mg rarr C_2H_5MgBr#;

#C_2H_5MgBr + H(O=C)CH_3rarrH_3C-CH_2CH(OH)CH_3#

(the alcohol results after aqueous workup of the magnesium alkoxide.)

#H_3C-CH_2CH(OH)CH_3 +Delta + H_3PO_4rarr"butylene + water"#

#"butylene"+H_2(g) rarr "n-butane"#

#2.# #"ethyl bromide "rarr" ethyl alcohol"#:

#C_2H_5Br + "KOH/NaOH" rarr C_2H_5OH + "KBr/NaBr"#

#3.# #"ethyl bromide "rarr" ethane"#:

#C_2H_5Br + "KOH/NaOH" rarr C_2H_5OH + "KBr/NaBr"#

#C_2H_5OH + H_3PO_4 rarr H_2C=CH_2 + H_2O#

#H_2C=CH_2 + H_2" (+metal catalyst)" rarr H_3C-CH_3#;

#4.# #"ethyl bromide "rarr" ethyl chloride"#:

#C_2H_5Br + KOBu^t rarr H_2C=CH_2 + KBr + Bu^tOH#

#H_2C=CH_2 + H-Cl rarr H_3C-CH_2Cl#;

#5.# #"ethyl bromide "rarr" acetic acid"#:

#C_2H_5Br + KOH rarr H_3C-CH_2OH + KBr#;

#H_3C-CH_2OH + KMnO_4 rarr H_3C-CO_2H + MnO_2#

#6.# #"ethyl bromide "rarr" ethylene":#

#C_2H_5Br + KOBu^t rarr H_2C=CH_2 + KBr + Bu^tOH#

#7.# #"ethyl bromide "rarr" propane"#:

#C_2H_5Br + Mg rarr C_2H_5MgBr#;

#C_2H_5MgBr + O=C(OC_2H_5)_2 rarr# #H_3C-CH_2C(=O)OCH_2CH_3#

#H_3C-CH_2C(=O)OCH_2CH_3 + LiAlH_4rarr#
#H_3C-CH_2CH_3#
This reduction reaction would be hard to accomplish.

Again, these are suggestions. There are many possibilities.