Several studies have shown that β-carotene, a precursor of vitamin A, may play a role in preventing cancer. β-Carotene has a molecular formula of C₄₀H₅₆, and it contains two rings and no triple bonds. How many double bonds does it have?

What is the index of hydrogen deficiency for each of the following molecular formulas?

(b) C₁₂H₁₁NO₃

Calculate the index of hydrogen deficiency for the following molecules.

(c)

For each molecular formula, represent all constitutional isomers using line-angle drawings.

(c) C₄H₁₀

Determine the degree of unsaturation for hydrocarbons with the following molecular formulas:

c. C₁₂H₂₀

d. C₄₀H₅₆

Give five examples of structures with this formula (C₆H₁₂). At least one should contain a ring, and at least one should contain a double bond.

Hint: If you prefer to use a formula, elements of unsaturation = 1/2(2C + 2 - H)

C = number of carbons

H = number of hydrogens

For each of the following molecular formulas, determine the number of elements of unsaturation, and draw three examples.

a. C₄H₄Cl₂

b. C₄H₈O

c. C₆H₈O₂

For each of the following molecular formulas, determine the number of elements of unsaturation, and draw three examples. 

d. C₅H₅NO₂

e. C₆H₃NClBr 

Calculate the index of hydrogen deficiency for curacin A, which has a molecular formula of C₂₃H₃₅NOS .