I think there is 4 electrons in the outer shell of 14 atomic number. If I'm wrong, know that I'm not very good.
The answer is A. Mom carefully bandaged my finger.
Answer:
-1190.24 kJ
Explanation:
The enthalpy change in a chemical reaction that produces or consumes gases is given by the expression:
ΔH = ΔU + Δngas RT
where Δn gas is the change of moles of gas, R is the gas constant,and T is temperature.
Now from the given balanced chemical reaction, the change in number of mol gas is equal to:
Δn gas = mole gas products - mole gas reactants = 2 - 5/2 = -1/2 mol
Sionce we know ΔU and the temperature (298 K), we are in position to calculate the change in enthalpy.
ΔH = -1189 x 10³ J + (-0.5 mol ) 8.314 J/Kmol x 298 K
ΔH = -1.190 x 10⁶ J = -1.190 x 10⁶ J x 1 kJ/1000 J = -1.190 x 10³ J
The set that represent a pair of isotope is 9B AND 11B.
Isotopes are chemical element which have two or more forms, these forms have the same number of electrons but different number of neutrons.
In an atom of an element, the nucleus contains the neutron and the proton. For a neutral atom, the number of proton and neutron are always the same, while the number of neutron differ. Thus, for the correct option, B stands for the element Boron, which has atomic number of 5. This means that 9B has 5 electrons, 5 protons and 4 neutrons. For 11B, the isotope has 5 protons, 5 electrons and 6 neutrons. 9 and 11 are the mass number of the isotopes; mass number is the summation of number of proton and neutron.
A substance in the air which can change the surface of limestone would be oxygen, O2.
