Thinking about simple organic molecules made with only carbon and hydrogen and no other elements (hydrocarbons), what are four different ways to make new
molecules? (Hint: Two versions of the same "way" only count as one thing!)

Explanation:

Simple organic molecules having only carbon and hydrogen are alkanes, alkenes and alkynes.

Ways of making these molecules are referred to as synthesis

Synthesis of

(1) alkanes can be achieved by halogenation of an alkene or alkyne as shown in the reaction below

C₂H₄ + H₂ ⇒ C₂H₆

The reaction above shows an alkene (ethene) undergoing halogenation to form an alkane (ethane). This reaction occurs in the presence of a platinum or nickel catalyst

C₂H₂ + 2H₂  ⇒ C₂H₆

The reaction above shows an alkyne (ethyne) undergoing halogenation to form an alkane (ethane). This reaction also occurs in the presence of a nickel or platinum catalyst

(2) Alkanes can be achieved by Wurtz reaction; treating alkyl halides with sodium metal as shown below

CH₃CH₂Br + 2Na + BrCH₂CH₃ ⇒ CH₃CH₂CH₂CH₃ + 2NaBr

This reaction proceed in the presence of a dry ether.

(3) alkanes from Kolbe's electrolytic method; this involves the synthesis of alkanes through the electrolysis of sodium or potassium salt of a carboxylic acid

2CH₃COO⁻Na⁺ + 2H₂O  ⇒ CH₃CH₃ + 2CO₂ + H₂ + 2NaOH

(4) alkenes from dehydration of alcohol, as shown in the reaction below

C₂H₅OH ⇒ C₂H₄    (-H₂O)

The reaction above proceeds by heating the alcohol (ethanol) at high temperature in the presence of strong acid such as sulphuric acid.

the answer is a and have a great day