What is the temperature of 0.5 moles of water vapor that occupies 120 dm3 and applies a pressure of 15,000 pa to its container

Use the ideal gas law:

PV = nRT

so, T = PV / nR

n=0.5
V= 120 dm^3 = 120 L  (1 dm^3 = 1 L)
R = 1/12
P = 15,000 Pa =  0.147 atm     (1 pa = 9.86 10^{-6} )

Put the values:

T = PV / nR
T = (0.147) (120) / (0.5) (1/12)
T= 426 K

Both the observations are a type of chemical change.

Explanation:

A physical change is defined as the change which occurs when there is no change in the composition of a substance. The physical state of the substance is changed. No new substance is formed.

A chemical change is defined as the change which occurs when there is change in the composition of a substance. New substance is formed at the end of the reaction.

There are many indicators which show us that a chemical change is happening in the reaction:

Change in colorFormation of bubblesChange in temperatureFormation of precipitateCharacteristic Odor

For the reaction of vinegar and baking soda, the equation follows:

For the observations given in the question:

Observation 1. In this observation, the temperature is being decreased because this reaction is an endothermic process. As there is change in temperature, hence it is considered as a chemical change.

Observation 2: In this observation, gas bubbles are formed due to the release of carbon dioxide gas. As there is formation of bubbles in this reaction. Hence, it is considered as a chemical change.