Sodium (na) reacts with chlorine gas (cl2) to form sodium chloride (nacl) as shown in the equation

2na+cl2=2nacl

if 4 moles of sodium react, how many moles of chlorine gas will react?

Answer : 2 moles of chlorine gas will react with the 4 moles of sodium.

Solution : Given,

Moles of sodium, (Na) = 4 moles

The given balanced chemical reaction is,

From the given balanced reaction, we conclude that

As, 2 moles of sodium(Na) react with 1 moles of chlorine gas

So, 4 moles of sodium(Na) react with moles of chlorine gas

Therefore, 2 moles of chlorine gas will react with the 4 moles of sodium.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

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.