The correct answer is option 1, which states that the hydrogen atoms present in an acetylene molecule are acidic.

Acetylene is a hydrocarbon with the chemical formula C2H2. In its structure, it contains two carbon atoms (C) and two hydrogen atoms (H). Acetylene is a highly flammable gas and is commonly used for welding and cutting metals.

When acetylene reacts with water, it undergoes an acidic hydrolysis reaction where the hydrogen atoms are replaced by water molecules. This reaction forms acetic acid, which is a weak acid.

Therefore, the hydrogen atoms in acetylene can be considered acidic because they can be easily replaced by water molecules and form acids. These hydrogen atoms are more acidic compared to other hydrogen atoms in hydrocarbons due to the sp-hybridization of carbon atoms in the acetylene molecule.

In summary, the hydrogen atoms in an acetylene molecule are acidic because they readily react with water to form acids.