An electrochemical cell has the following standard cell notation.

mg(s) | mg^2+ (aq) || aq^+(aq) | aq(s)

write a balanced redox equation for the cell using the oxidation and reduction half-reactions. (be sure to equalize charge by multiplying by the correct numbers before adding and simplifying)

The given cell notation is:  

Thus here Mg is undergoing oxidation [as written on left side]

silver is undergoing reduction [ as written on right side]

In oxidation Magnesium will lose two electrons per atom

In reduction silver will gain one electron per atom

In order to balance the redox reaction we will multiply silver with two so that overall there will be exchange of two electrons

Oxidation half reaction:

Reduction half reaction:

Now we will multiply the reduction equation by two

Overall redox reaction:

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.