Answer:
If you mean the number of atoms in 8g of oxygen, it's 3.011 x 10^23 atoms.
Explanation:
Convert the grams to moles. 8 grams of oxygen is 0.5 moles. Then multiply the number of moles by Avogadro's number: 6.022 x 10^23.
CaCO₃ partially dissociates in water as Ca²⁺ and CO₃²⁻. The balanced equation is,
CaCO₃(s) ⇄ Ca²⁺(aq) + CO₃²⁻(aq)
Initial Y - -
Change -X +X +X
Equilibrium Y-X X X
Ksp for the CaCO₃(s) is 3.36 x 10⁻⁹ M²
Ksp = [Ca²⁺(aq)][CO₃²⁻(aq)]
3.36 x 10⁻⁹ M² = X * X
3.36 x 10⁻⁹ M² = X²
X = 5.79 x 10⁻⁵ M
Hence the solubility of CaCO₃(s) = 5.79 x 10⁻⁵ M
= 5.79 x 10⁻⁵ mol/L
Molar mass of CaCO₃ = 100 g mol⁻¹
Hence the solubility of CaCO₃ = 5.79 x 10⁻⁵ mol/L x 100 g mol⁻¹
= 5.79 x 10⁻³ g/L
Answer : The heat of the reaction is, 1.27 kJ/mole
Explanation :
First we have to calculate the heat released.
Formula used :
or,
where,
Q = heat = ?
m = mass of sample = 1.50 g
c = specific heat of water = 
= initial temperature = 
= final temperature = 
Now put all the given value in the above formula, we get:
Now we have to calculate the heat of the reaction in kJ/mol.
where,
= enthalpy change = ?
Q = heat released = 0.0238 kJ
n = number of moles NH₄NO₃ = 
Therefore, the heat of the reaction is, 1.27 kJ/mole
I believe your answer is A. Octane
Radiometric dating
hope this helps
