Final answer:
Atmospheric pressure contributes to the overall pressure in a flexible container like a toy balloon but not in a rigid tank. In a rigid, sealed environment, atmospheric pressure does not affect the total pressure in the fluid, aligning our answer with option (b).
Step-by-step explanation:
Atmospheric pressure does indeed add to gas pressure in a container, affecting its overall pressure, a concept that can be explained by Pascal's principle. However, its influence depends on whether the container is rigid or flexible. In a rigid tank, the gas pressure inside is increased by the amount of gas and how it is compressed, but the atmospheric pressure does not further add to this pressure because the tank's rigidity prevents the outside atmospheric pressure from influencing the internal pressure.
On the other hand, in a toy balloon, which is not a rigid container, the atmospheric pressure does contribute to the overall pressure. This is because the balloon can expand and contract, adjusting to the external pressure. This means the gas pressure inside the balloon is actually the sum of the pressure due to the gas itself and the external atmospheric pressure. Generally, atmospheric pressure does not affect the total pressure in a fluid when the fluid is contained in a rigid, sealed environment, where internal pressures are isolated from external atmospheric influences. Therefore, the correct option that describes when atmospheric pressure affects the total pressure in a fluid is: (b) Atmospheric pressure adds to gas pressure in a rigid tank but not in a toy balloon.