Calculate the edge length of unit cell if metal having atomic radius 170 pm forms simple cubic unit cell.

In a simple cubic unit cell, atoms are located at the corners and contact each other along the cube edges.
This implies the edge length $a$ is equal to twice the atomic radius: $a = 2r$.

Given $r = 170 \text{ pm}$, convert to centimeters using $1 \text{ pm} = 10^{-10} \text{ cm}$:
$r = 170 \times 10^{-10} \text{ cm} = 1.70 \times 10^{-8} \text{ cm}$.

Substitute into the relation:
$a = 2 \times 1.70 \times 10^{-8} = 3.40 \times 10^{-8} \text{ cm}$.

This value corresponds to option B.