The answer is A. Isotopes only differ in the number of neutrons in the nucleus of their atoms. Otherwise, all other subatomic particles are the same. The isotope with the more neutrons in its nucleus is therefore, heavier (have higher mass number). They share the same chemical properties but have slight physical differences such as boiling points with the heavier element having a slightly higher boiling point that the lighter element.
It is an example of physical change. The molecules are not changing, so it is not chemical, and a physical property is something that a physical thing has.
Answer:- 
Explanations:- Alkanes are non polar molecules as these only have carbons and hydrogens. Electron negativity difference of C and H is very low and it makes them non polar. These have weaker London dispersion forces.
The forces of attraction becomes stronger in alkanes as the number of carbon increases because the surface area as well as molecular weight of the alkanes increases with an increase in number of carbons.
Butane has four carbons, propane has three carbons, ethane has two and methane has only one carbon, So, the strongest to weakest order of inter molecular forces is butane > propane > ethane > methane .
Answer:
C. The lowest-energy electron configuration of an atom has the maximum number of unpaired electrons, all of which have the same spin, in degenerate orbitals.
Explanation:
The Hund's rule is used to place the electrons in the orbitals is it states that:
1. Every orbital in a sublevel is singly occupied before any orbital is doubly occupied;
2. All of the electrons in singly occupied orbitals have the same spin.
So, the electrons first seek to fill the orbitals with the same energy (degenerate orbitals) before paring with electrons in a half-filled orbital. Orbitals doubly occupied have greater energy, so the lowest-energy electron configuration of an atom has the maximum number of unpaired electrons, and for the second statement, they have the same spin.
The other alternatives are correct, but they're not observed by the Hund's rule.
Answer:
See explanation below
Explanation:
In an electrochemical cell, electricity is obtained by the gradual deterioration of the anode.
Hence, surface area of the metal will affect the length of time within which the electrochemical cell works.
The greater the surface area of the metal, the longer the electrochemical cell can function and the greater the quantity of electricity produced, hence the answer above.
