Which one of the following chemical substances exists as a gas under ordinary conditions and room temperature?

The physical state of tetrahalomethanes at room temperature is determined by the strength of their intermolecular forces, specifically London dispersion forces, which increase with molecular mass [c4][t8]. Carbon tetrafluoride (CF4) is a simple covalent molecule with a low molecular weight (88 g/mol) and weak intermolecular attractions, causing it to exist as a colorless, odorless gas under ordinary conditions [c2][t6]. In contrast, as the halogen size increases, the boiling points rise significantly [c4]. Carbon tetrachloride (CCl4) is a liquid at room temperature due to stronger dispersion forces [t1][t3], and carbon tetrabromide (CBr4) is a solid [t4]. The option Cl4 (chlorine tetramer) is not a standard stable chemical substance under ordinary conditions compared to the well-characterized tetrahalomethanes. Therefore, CF4 is the only substance among the choices that is a gas at room temperature [t6].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > 4.1 BONDING IN CARBON – THE COVALENT BOND > p. 60
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > 4.2.4 Homologous Series > p. 67
3. [3] https://pubchem.ncbi.nlm.nih.gov/compound/Carbon-tetrafluoride