At which of the following conditions can a gas be liquified? `T_(c)` and `P_(c)` are critical temperature and pressure.

Options

A. `T=T_(c)` and `P lt P_(c)`
B. `T lt T_(c)` and `P=P_(c)`
C. `T gt T_(c)` and `P lt P_(c)`
D. `T lt T_(c)` and `P lt P_(c)`

Explanation

To determine the conditions under which a gas can be liquefied, we need to consider the concepts of critical temperature (Tc) and critical pressure (Pc). Here’s a step-by-step solution:

### Step 1: Understand Critical Temperature and Pressure
- **Critical Temperature (Tc)**: This is the temperature above which a gas cannot be liquefied, regardless of the pressure applied. If the temperature of the gas is above Tc, it will remain in the gaseous state.
- **Critical Pressure (Pc)**: This is the pressure required to liquefy a gas at its critical temperature. Above this pressure, the distinct phases of liquid and gas do not exist.

### Step 2: Conditions for Liquefaction
For a gas to be liquefied, the following conditions must be satisfied:
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