Answer:
7.6 days
Explanation:
Radon is a radioactive element and Radon-222 is it's most stable isotope. The half-life of Radon-222 has been found to be approximately 3.8 days.
Let, the initial amount of the Rn-222 = 1 = A
Final amount = 
= A'
We will use the following relation for calculating time elapsed in the decay
Thus,
We can write is as,
Since the base in both sides are equal, powers can also be equal and thus,
So, t = 7.6 days
28 degrees below freezing would be 4 degrees
The maximum concentration of calcium ions (Ca₂+) in a solution that
contains CO₃ will be 6.18 × 10⁻⁸. The correct option is D).
<h3>What is concentration?</h3>
The concentration of any substance is the presence or the amount of that substance in a specific place. It is also called the molar mass of the substance.
Ksp is the solubility equilibrium of a substance when it remains in its solid state.
The chemical equation will be
CaCO₃ ⇌Ca²⁺+CO₃²⁻
Ksp = [Ca²⁺][CO₃²⁻]
given Ksp = 3.4 × 10⁻⁹ [CO₃²⁻] = 0.055M
[Ca²⁺] = Ksp / [CO₃²⁻] 3.4×10⁻⁹ / 0.055 = 6.18 × 10⁻⁸
Thus, the Ksp of CaCO₃ = 6.18 × 10⁻⁸. The correct option is D).
To learn more about concentration, refer to the link:
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Answer:
Check Explanation.
Explanation:
Formation reactions are chemical reactions where one mole of a compound is produced from its constituent elements in their standard states.
NaBr (s)
The Standard formation reaction is
Na (s) + (1/2)Br₂ (g) → NaBr (s)
Using appendix C, the standard heat of formation of NaBr(s) is
ΔH∘f = -359.8 kJ/mol.
SO₃ (g)
The Standard formation reaction is
S (s) + (3/2) O₂ (g) → SO₃ (g)
Using appendix C, the standard heat of formation of SO₃(g) is
ΔH∘f = -395.2 kJ/mol.
Pb(NO₃)₂ (s)
The Standard formation reaction is
Pb (s) + N₂ (g) + 3O₂ (g) → Pb(NO₃)₂ (s)
Using appendix C, the standard heat of formation of Pb(NO₃)₂(s) is
ΔH∘f = -451.9 kJ/mol.
Hope this Helps!!!
