Acetylene dissolves in acetone but not in water Explain the observation.

Explanation

Because of considerable electronegativity of the sp-hybridised C-atom of acetylene, the aetylenic hydrogen gets involved in intermolecular H-bonding with the O-atom of acetone. As a consequence, acetylene dissolves in acetone. Since energy of the H-bond formed is greater than the weak van der waals' attractive forces acting among the acetylene molecules and dipole-dipole attractive forces operating among the acetone molecules, the process of dissolution occurs easily.
`underset("Acetylene")(H-C -= overset(delta-)(C)-overset(delta+)(H)) overset("H-bond")(- - - -) underset("Acetone")(overset(delta-)(O)=overset(delta+)(C)(CH_(3))_(2))`
On the other hand, the intermolecular H-bonding between water molecules is stornger than the intermolecular Hbonding between water and acetylene molecules, if formed. so, acetylene shows no tendency to form H-bonds with water. hence, acetylene does not dissolve in water.