Two gaseous molecules `A` and `B` are traveling towards each other. Let the mean free path of the molecule be `sigma` and `Z` be the collision number with other molecules at pressure `1 atm`. Answer the following questions
If `Z` is the total number of collisions which a gas molecule registers with others per unit time under particular conditions, then the collision frequency of the gas containing `N` molecules per unit volume is

Options

A. `(Z)/(N)`
B. `NZ`
C. `2NZ`
D. `(NZ)/(2)`

Explanation

To solve the problem, we need to determine the collision frequency of a gas containing \( N \) molecules per unit volume, given that \( Z \) is the total number of collisions a gas molecule registers with others per unit time.

### Step-by-Step Solution:

1. **Understanding Collision Frequency**:
- The collision frequency \( Z \) represents the total number of collisions that a single gas molecule experiences with other molecules in a unit of time.

2. **Considering the Number of Molecules**:
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