Answer: option C. 2 and 3.
Explanation:
1) Isotopes are atoms of a same element with different number of neutrons. That means that the isotopes of a same element have the same number of protons, since the number of protons is what identify an element.
2) For example, all the atoms of oxygen have 8 protons. But isotope oxygen-16 has 8 neutrons, while oxygen-18 has 10 neutrons.
3) In the figure there are 3 different atoms:
i) atom # 1 has 5 protons and 7 neutrons
ii) atom # 2 has 6 protons and 7 neutrons
iii) atom # 3 has 6 protons and 8 neutrons.
4) Hence the atoms with the same number of protons and different number of neutrons are the #2 and the # 3. So, they are the isotopes of the same element.
Answer: 625 kj/mol
Explanation:
As shown below this expression gives the activation energy of the reverse reaction:
EA reverse reaction = EA forward reaction + | enthalpy change |
1) The activation energy, EA is the difference between the potential energies of the reactants and the transition state:
EA = energy of the transition state - energy of the reactants.
2) The activation energy of the forward reaction given is:
EA = energy of the transition state - energy of [ NO2(g) + CO(g) ] = 75 kj/mol
3) The negative enthalpy change - 250 kj / mol for the forward reaction means that the products are below in the potential energy diagram, and that the potential energy of the products, [NO(g) + CO2(g) ] is equal to 375 kj / mol - 250 kj / mol = 125 kj/mol
4) For the reverse reaction the reactants are [NO(g) + CO2(g)], and the transition state is the same than that for the forward reaction.
5) The difference of energy between the transition state and the potential energy of [NO(g) + CO2(g) ] will be the absolute value of the change of enthalpy plus the activation energy for the forward reaction:
EA reverse reaction = EA forward reaction + | enthalpy change |
EA reverse reaction = 375 kj / mol + |-250 kj/mol | = 375 kj/mol + 250 kj/mol = 625 kj/mol.
And that is the answer, 625 kj/mol
Flame colors are produced from the movement of the electrons in the metal ions present in the compounds. When you heat it, the electrons gain energy and can jump into any of the empty orbitals at higher levels Each of these jumps involves a specific amount of energy being released as light energy, and each corresponds to a particular color. As a result of all these jumps, a spectrum of colored lines will be produced. The color you see will be a combination of all these individual colors.
