An atom that has 13 protons and 15 neutrons is isotope of Aluminium (answer C)
<u><em>Explanation</em></u>
- Isotope is a form of the same element with the equal number of protons but difference number of neutrons in their nuclei.
- In other words isotope has the same atomic number but different mass number.
- Atomic number of a element is determined by number of protons of an element.
- from the periodic table Aluminum in atomic number 13 therefore it has 13 protons <em>therefore an atom that has 13 protons and 15 neutrons is a isotope of Aluminium. </em>
It represents the number of moles required of that molecule to balance the chemical equation, which means to have the reaction chemically happen and goes to completion.
For example:
CH4 + O2 --> H2O + CO2 that is not balanced
with the coefficients located
CH4 + 2O2 --> 2H2O + CO2 now with the coefficients the number of oxygen and hydrogen on each side are equal
Answer:
The correct answer is entropy change of the surrounding plus the entropy change of the system must be positive.
Explanation:
The term entropy is a state function.Entropy can be defined as the disorder or randomness of the molecules in a system.
A spontaneous reaction is a type of reaction which deals with the release of free energy.The change of free energy in case of spontaneous reaction is always negative.
According to the second law of thermodynamics a spontaneous reaction will occur in a system if the total entropy of both system and surrounding increases during the reaction.
Answer: The amount of water produced is 9.3 grams
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

mass of reactants = mass of methane + mass of oxygen = 22.5 g + 35.7 g = 58.2 g
mass of products = mass of carbon dioxide + mass of water = 48.9 g + mass of water
48.9 g + mass of water = 58.2 g
mass of water = 9.3 g