Answer:
For isotopes, the difference between the mass number and number of neutrons is constant.
Explanation:
Isotopes are atoms with the same atomic number but different mass numbers.
Number of neutrons in an atom can be obtained by subtracting the atomic number from the mass number.
So in other words , isotopes are atoms for which the difference between the mass number and number of neutrons is constant.
For example, Hydrogen,Deuterium and Tritium are isotopes of Hydrogen in which the difference between mass number and number of neutrons is 1.
Answer:
The number of valence electrons increases from left to right.
Explanation: The number of valence electrons increases going across a period, or row in the periodic table, for example, group 1 elements have 1 valence electrons and group 2 elements have have 2.
Energy released from changing the phase of a substance from the gas phase to liquid phase can be calculated by using the specific latent heat of vaporization. The heat of fusion of water at 0 degrees Celsius is 40.7 kJ/mol. Calculation are as follows:<span> </span>
Energy = 27.9 g (1 mol / 18.02 g) x 40.7 kJ/mol
Energy = 63.09 kJ