Answer:
Use the activity formula,
T1/2 = 4.468 x 10^9 yr x 365 x 24 x 3600 = 1.409 x 10^17 sec
l = ln(2)/T1/2 = ln(2)/1.409 x 10^17 = 4.91932697 x 10^-18 s-1
DN/Dt = lN, 265 = 4.91932697 x 10^-18 x N
<u><em>N = 5.38 x 10^19 nuclei</em></u>
Assuming that both cases describe hydrogen‑like atoms with one electron, More energy is emitted or absorbed for case 2. The correct option is D.
<h3>What is emitting of energy, by electron?</h3>
The energy of the electron decreases as it changes levels, and emission of photons happens in the atom.
With the electron moving from a higher to a lower energy level, the photon is emitted. The photon's energy is the same as the energy lost by an electron moving to a lower energy level.
Thus, the correct option is D, More energy is emitted or absorbed for case 2.
Learn more about emitting of energy
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<span>#1 is air radon, #2 is x-ray, #3 is ground, #4 is cosmic radiation, #5 is TV tube, #6 is weapons test fallout . That's all I got hope I helped!</span>
Mass of H₂ needed to react with O₂ : 1.092 g
<h3>Further explanation</h3>
The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight / volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.
Reaction
O₂(g) + 2H₂(g) → 2H₂O(g)
mass of O₂ : 8.75 g
mol O₂(MW=32 g/mol) :

From the equation, mol ratio of O₂ : H₂ = 1 : 2, so mol H₂ :

Mass H₂ (MW=2 g/mol) :

Answer:
add 7.5L of water
Explanation:
M1×V1=M2×V2
M is molarity, V is volume
0.7 × 10 = 0.4 × V2
V2= 17.5L
vol. of water to add= 17.5 - 10 = 7.5L