Chemistry NCERT Exemplar Solutions Class 11th Chapter Eight

This is a Long answer type question as classified in NCERT Exemplar

On the basis of standard reduction potential suggested in the reactivity series (ii) reaction can take place as Mg has more negative value of E? cell. Hence, Mg will be oxidized by losing electron and iron will be reduced by gaining electron.

This is a Long answer type question as classified in NCERT Exemplar

The given reaction is a redox change. 

2Na (s)+H₂ (g)→2NaH (s)   

The half reaction is:

2Na (s)→2Na⁺ (g)+2e^-

The other half reaction is:

H₂ (g)+2e^-→2H^- (g)

This splitting of the reaction into two half-reactions automatically reveals here that sodium is oxidized, and hydrogen is reduced. Any substance which loses electron is oxidized and gains electron is reduced hence is the case of sodium and hydrogen atoms respectively. Hence, the complete reaction is a redox change.