Step 1: Structure of C_6H_6
The given compound is C_6H_6, which is benzene. The structure of benzene consists of six carbon atoms arranged in a hexagonal ring, with alternating single and double bonds between them. Each carbon atom is bonded to one hydrogen atom.
Step 2: Valency of Carbon
Carbon has an atomic number of 6, and its electron configuration is 1s\(^2\) 2s\(^2\) 2p\(^2\). Carbon needs four electrons to complete its octet, which gives it a valency of 4. This allows each carbon atom in the benzene ring to form four bonds—one with a hydrogen atom and three with other carbon atoms.
Step 3: Conclusion
Thus, the valency of carbon (C) in C\(_6\)H\(_6\) (benzene) is 4.
\[
\boxed{4}
\]
$PQ$ is a chord of length $4\ \text{cm}$ of a circle of radius $2.5\ \text{cm}$. The tangents at $P$ and $Q$ intersect at a point $T$. Find the length of $TP$.