Answer:
30, 50
Explanation:
Hello,
In this since an element's atomic number is equal to the number of protons in its atom, we can infer that selenium's atomic number is 30. Moreover, due to the fact the the neutrons are equal to the atomic mass minus the atomic number or the number of protons, by knowing the number of neutrons we compute the atomic as follows:

Thus, answer is 30, 50.
Best regards.
The magnesium dissolves to form magnesium chloride and hydrogen gas is released.
Mg + 2HCl -----> MgCl2 + H2(g).
Answer:
D
Explanation: this was easy for me
Answer:
The reaction is endothermic.
Yes, absorbed
3.06x10¹kJ are absorbed
Explanation:
In the reaction:
2HgO(s) → 2Hg(l) + O₂(g) ΔH = 182kJ
As ΔH >0,
<em>The reaction is endothermic</em>
<em />
As the reaction is endothermic, when the reaction occurs,
<em>the heat is absorbed.</em>
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Now, based on the equation, when 2 moles of HgO (Molar mass: 216.59g/mol), 182kJ are absorbed.
72.8g are:
72.8g * (1mol / 216.59g) = 0.3361 moles HgO.
that absorb:
0.3361 moles HgO * (182kJ / 2 moles) =
<h3>3.06x10¹kJ are absorbed</h3>
Answer:
the concentration of the solution is 0.00906 M
Explanation:
Given the data in the question;
we know that from Nernst Equation;
E = E⁰ - ((0.0592/n) logQ)
now, E₀ for concentration cell is 0
n for this redox is 2
concentration of the unknown solution is x
so we substitute
0.045 = 0 - ( 0.0592 / 2)log( x/0.300 ))
0.045 = -0.0296log( x/0.300 )
divide both side by 0.0296
1.52 = -log( x/0.300 )
x/0.300 =
x/0.300 = 0.0301995
we cross multiply
x = 0.300 × 0.0301995
x = 0.00906 M
Therefore, the concentration of the solution is 0.00906 M