All of the following are part of the digestive system except the
select one of the options below as your
a. stomach
b. esophagus
c. intestines
d. heart

The heart doesn't do anything to the digested food, so the heart isn't part of the digestive system. P.S. this seems like a biology question, not chemistry.

The heart is of circulatory system. Therefore, d. heart is the correct answer~

The answer is 4 i don't know if its right let me see.

We first assume that this gas is an ideal gas where it follows the ideal gas equation. the said equation is expressed as: pv = nrt. from this equation, we can predict the changes in the pressure, volume and temperature. if the volume and the temperature of this gas is doubled, then the pressure still stays the same.