Action of Zinc on Tetrahalide

Q. The reagent used for converting tetrabromoethane into ethyne is:

1. Alcoholic KOH
2. Conc. $H_{2}S{O}_4\text{at}{170}^{o}C$
3. Aqueous potash
4. Zinc dust

Q. 1, 1, 2, 2-tetra bromo ethane on heating with Zn powder in alcohol finally gives:

1. Methane
2. Ethane
3. Ethyne
4. Ethane

Q. To prepare But- 2 - yne from 2, 2, 3, 3- tetrachlorobutane, reagent used is:

1. Zinc dust / $\Delta$
2. Alc. KOH
3. aq. KOH
4. All of the above