It depends on what type of graph you have. The easiest would be using a H-T diagram. Enthalpy of vaporization is the physical change from liquid to vapor. It occurs at a constant pressure and a constant temperature. As shown in the picture, 1 point is drawn on the subcooled liquid, and another point of the saturated vapor isothermal line. Now, the difference between those two points is the value for the enthalpy of vaporization of water.
Answer: When the electrons in an element are more than the required, a bond is formed with other element which has deficiency of electron and in case when electrons are less in numbers the vice versa happens. Such kind of chemical bonds are known as ionic bond.
Explanation:
Answer:
C. Energy is absorbed and released during chemical reactions,
Explanation:
All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. Endothermic reactions absorb energy, and exothermic reactions release energy.
Answer:
unchanged
Explanation:
In any chemical of physical process, energy is neither created nor destroyed. A process that absorbs the heat from the surroundings. ... What happens to the energy of the universe during a chemical or physical process? During any chemical or physical process, the energy of the universe remains unchanged.
The symbol : 
<h3>Further explanation
</h3>
There are two components that accompany an element, the mass number and atomic number
Atoms are composed of 3 types of basic particles (subatomic particles): <em>protons, electrons, and neutrons
</em>
The Atomic Number (Z) indicates the number of protons and electrons in an atom of an element.
Atomic number = number of protons = number of electrons ⇒ neutral number
Atomic mass is the sum of protons and neutrons
Atomic Number (Z) = Atomic mass (A) - Number of Neutrons
The element has 71 electrons and a charge of +1 , so
Number of protons = 71 + 1 = 72
Number of protons = the atomic number = 72
The element with atomic number 72 is Hafnium(Hf)
The atomic mass of Hf = 178 g/mol
