¿Un litro de agua a 100°C posee igual cantidad de calor que dos litros de agua, a igual temperatura? ¿Por qué?

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.