Question

question 9 (1 point)
the number of isomers of 1,2 - dibromo - 3 - chlorobenzene is which of the following?
three
four
five
six
seven
question 10 (1 point)
which compound is a structural isomer of the compound shown below?
\\( \begin{array} { c } { mathrm { ch } _ { 3 } } \\ { mathrm { ch } _ { 3 } - mathrm { c } - mathrm { ch } _ { 3 } } \\ { mathrm { ch } _ { 3 } } end{array} \\)
propane
butane
methane
pentane
hexane

Explanation:

Question 9

For 1,2 - dibromo - 3 - chlorobenzene, we consider the positions of the substituents on the benzene ring. The general formula for calculating the number of isomers of a trisubstituted benzene (where two substituents are the same and one is different) can be thought of by fixing two substituents (the bromine atoms in this case) and then moving the third substituent (the chlorine atom).
When two bromine atoms are in 1,2 positions, the chlorine atom can be placed in 3,4,5 positions relative to the bromine - substituted ring. So there are three possible isomers.

First, find the molecular formula of the given compound. The given compound \(CH_3 - C(CH_3)_2 - CH_3\) has the molecular formula \(C_5H_{12}\).

• Propane has the formula \(C_3H_8\).
• Butane has the formula \(C_4H_{10}\).
• Methane has the formula \(CH_4\).
• Pentane has the formula \(C_5H_{12}\). Structural isomers have the same molecular formula but different structural arrangements.
• Hexane has the formula \(C_6H_{14}\).

Answer:

three

Question 10