Does a reaction occur when an aqueous solution of nicl2(aq) is added to a test tube containing strips of metallic zinc?

To know if a reaction would occur, we refer to the reactivity series. Looking at the reactivity series, the zinc is at the upper list than nickel, therefore we could say that a reaction would occur. This would actually be a replacement reaction:

NiCl2  +  Zn  -->  ZnCl2  +  Ni

Answer is: yes, reaction occurs.

Reactivity series is an empirical progression of a series of metals, arranged by their reactivity from highest to lowest (alkaline metals have highest reactivity and Noble metals lowest reactivity).

Metal higher in the reactivity series will displace another, zinc is more reactive than nickel.

Chemical reaction: Zn(s) + NiCl₂(aq) → ZnCl₂(aq) + Ni(s).

Ionic reaction: Zn(s) + Ni²⁺(aq) + 2Cl⁻(aq) → Zn²⁺(aq) + 2Cl⁻(aq) + Ni(s).

Net ionic reaction: Zn(s) + Ni²⁺(aq) → Zn²⁺(aq) + Ni(s).

Zinc metal is oxidized (from oxidation number 0 to +2) and nickel is reduced (from oxidation number +2 to 0).

gold is my favorite solid.

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.