The compound CCl4 is nonflammable and was once commonly used in fire extinguishers. On the basis of — Atomic Structure Chemistry Question

STEPS:

1. Analyze the chemical characteristics of the reference compound:
Carbon tetrachloride ($\text{CCl}_4$) is a nonpolar, covalent molecule consisting of a central carbon atom (Group 14) bonded to four chlorine atoms (Group 17, halogens) in a symmetrical tetrahedral geometry. Its nonflammability and fire-resistant nature stem from the highly stable carbon–halogen bonds and the lack of weak bonds (like $\text{C–H}$) that can be readily oxidized by oxygen.
2. Apply the concept of periodic groups and chemical similarity:
Elements in the same group of the periodic table share the same number of valence electrons and exhibit highly similar chemical reactivity and bonding behaviors.
* To find a compound with properties most similar to $\text{CCl}_4$, we should look for a molecule that maintains a central Group 14 atom bonded to four Group 17 halogen atoms ($\text{XY}_4$).
3. Compare the options to the target molecular profile:
* $\text{CBr}_4$ (carbon tetrabromide) features a central carbon atom (Group 14) bonded to four bromine atoms.
* Since bromine is directly below chlorine in Group 17, it shares a nearly identical valence electron configuration and forms a similarly nonpolar, symmetrical tetrahedral molecular structure.
* Consequently, $\text{CBr}_4$ has periodic properties and chemical characteristics that are extremely similar to those of $\text{CCl}_4$, making it the most likely candidate to be used as a fire-resistant chemical.
4. Conclude: Option C is the correct answer.

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WHY_OTHERS_WRONG:

• Option A is incorrect: Boron ($\text{B}$) is in Group 13, not Group 14. $\text{BCl}_3$ is a trigonal planar molecule with an incomplete octet on the boron atom. It is highly reactive and hydrolyzes violently upon contact with water or moisture in the air to produce toxic hydrochloric acid, making it completely unsuitable and dangerous as a fire-safety chemical.
• Option B is incorrect: Methane ($\text{CH}_4$) replaces the non-combustible halogens with hydrogen (Group 1). Due to the high combustibility of carbon–hydrogen bonds, methane is highly flammable and is the primary component of natural gas; using it would fuel a fire rather than extinguish it.
• Option D is incorrect: Although lead ($\text{Pb}$) is in the same group as carbon (Group 14), it is a heavy metal. $\text{PbCl}_2$ is a solid, crystalline ionic salt with an extremely high melting point and entirely different physical and chemical properties than the volatile covalent liquid/gas molecular compounds used to smother fires.