Answer:
1) \(Zn(s)+2HCl(aq)--->ZnCl_{2}+H_{2}(g)\)
2) \(Zn+2H_{2}O+2NaO-->Na_{2}Zn(OH)_{4}+H_{2}(g)\)
3) \(3H_{2}(g)+W_{2}O_{3}--->3H_{2}O+2W(s)\)
4) \(CO(g)+2H_{2}(g)--->CH_{3}OH\)
Explanation:
The following happens:
(1)Zinc is put in dilute hydrochloric acid
There is an evolution of hydrogen gas as the Zinc undergoes oxidation by hydrogen and it reduces the hydrogen to hydrogen gas.
\(Zn(s)+2HCl(aq)--->ZnCl_{2}+H_{2}(g)\)
(2)Zinc is put in concentrated sodium hydroxide.
Again there is evolution of hydrogen gas and formation of zincate sodium. This happens when we heat the mixture.
\(Zn+2H_{2}O+2NaO-->Na_{2}Zn(OH)_{4}+H_{2}(g)\)
(3)Hydrogen is passed over hot tungsten oxide.
The hydrogen reduces the tungsten metal during the reaction and it gives solid tungsten metal.
\(3H_{2}(g)+W_{2}O_{3}--->3H_{2}O+2W(s)\)
(4) Hydrogen is reacted with carbon monoxide in presence of a catalyst.
This is producer gas reaction.
\(CO(g)+2H_{2}(g)--->CH_{3}OH\)