Which compound has the highest molar mass

Option (a) is the correct answer.

Explanation:

Molar mass of a substance means the sum of atomic masses of all the atoms present in a substance.

A polyethylene molecule is made up of "n" number of repeated units ethylene. Hence, it will have highest molar mass because there are more number of atoms present in a polyethylene molecule.

Whereas an ethane molecule is and its molar mass is = 30 g/mol

An octane molecule is and its molar mass is = 114 g/mol

An octanal molecule is and its molar mass is = 128 g/mol

Thus, we can conclude that polyethylene, a polymer of ethane has the highest molar mass.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2