The statement is partially correct. While hydrogen and helium are considered ideal gases at room temperature and ordinary pressure, sulfur dioxide (SO₂) is not an ideal gas under those conditions. Here's why:

* Ideal Gas Assumptions: Ideal gases are theoretical constructs that follow specific rules:

* Negligible intermolecular forces: Particles in ideal gases don't interact with each other, meaning they have no attraction or repulsion.

* Negligible particle volume: The volume of the gas particles is insignificant compared to the volume of the container.

* Why Sulfur Dioxide Deviates: Sulfur dioxide molecules are polar (have a positive and negative end), leading to stronger intermolecular forces (dipole-dipole interactions) compared to hydrogen and helium. These forces cause the molecules to stick together, affecting their behavior and making them deviate from ideal gas behavior.

In Summary:

* Hydrogen and Helium: These elements exist as single atoms, which are nonpolar and have extremely weak intermolecular forces. This makes them closer to ideal gas behavior at room temperature and pressure.

* Sulfur Dioxide: Due to its polarity and stronger intermolecular forces, sulfur dioxide deviates from ideal gas behavior at room temperature and pressure.

Important Note: Even ideal gases can deviate from ideal behavior at high pressures or low temperatures. Under these conditions, the assumptions of negligible intermolecular forces and particle volume become less valid.