B. Decomposition is the correct answer~
They have high melting and boiling points and are hard and brittle
Explanation: In IUPAC, E-Z convention is given for describing the cis - trans notation to the isomers. According to CIP rule, the groups on the doubly bonded carbon atoms are given priorities based on the the atomic masses of first connected atom.
If the highest priority groups are on the same side, it is known as Z-form and if the highest priority groups are on opposite side, it is known as E-form.
We are given (Z)-3-bromo-6-methyl-2-heptene, in this the highest priority groups are bromine on one side and methyl- group on another side.
The structure is provided in the image below.
Well what are all the calculations you have
Ca=40g
P=31g
Ca3=120g
P2=62g
Ca3P2=182g
Ca3/Ca3p2=120/182=0.6593=approximately 65.93%