Given the redox reaction in an electrochemical cell:

Ni(s) + Pb2+(aq) + Ni2+(aq) + Pb(s)

A salt bridge is used to connect

A) Ni(s) and Pb(s)

B) Pb2+(aq) and Ni2+(aq)

C) Ni(s) and Ni2+(aq)

D) Pb2+(aq) and Pb(s)

Please help me

Pb2+(aq) and Ni2+ B

Explanation:A salt bridge is a laboratory device used in an electrochemical cell  to connect the oxidation ( which occurs at the anode ) and reduction( which occurs at the cathode) half-cells of a galvanic cell voltaic cell, It prevents the cell from quickly  reaching equilibrium  by maintaining  electrical charge  neutrality within the internal circuit because the electrons are moving from one-half cell to the other.

In this electrochemical cell,  Ni (s) is oxidized to Ni2+(aq) and will occurs at the anode while  Pb2+(aq) is reduced to Pb (s) and will occur at the  cathode.

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.

i think it's letter a.