Final answer:
The question's context is unclear, but in engineering, 'burst pressure' would relate to the maximum pressure a material or container can withstand before fracturing. The provided example refers to gas cylinders with a known rupture pressure that can be assessed using gas laws for safety against rupture.
Step-by-step explanation:
The question appears to be related to the field of engineering, specifically dealing with the burst pressure of a material or container. Without additional context, it is challenging to provide a precise answer to the burst pressure for a '4"' specification as it could refer to a pipe diameter, thickness of a container, or be part of another engineering specification. However, the information provided mentions a rupture pressure of 40 atm for cylinders containing chlorine gas. If '4"' pertains to the diameter of such a cylinder, the burst pressure would then depend on the material and design of the cylinder. The information provided allows for the calculation of the pressure inside a cylinder containing a specific amount of chlorine and to assess the safety against sudden rupture using the ideal gas law and van der Waals equation for a given volume and temperature.
An example calculation in the context of a cylinder of compressed gas is given, but without further specifics about the '4"' reference, providing a precise burst pressure value is not possible. The example emphasizes the importance of ensuring that the pressure within a cylinder does not exceed its burst pressure to prevent disasters, especially when dealing with toxic gases like chlorine.