Answer:
C.) No. of electrons
Explanation:
A.) is incorrect. The atomic number represents the number of protons in an element. Nitrogen (N) and sodium (Na) always have a differing amount of protons.
B.) is incorrect. The mass number represents the number of protons and neutrons in an element. The number of neutrons and protons are specific to each element (disregarding isotopes). When elements ionize, these amounts are not altered.
C.) is correct. When an element becomes an ion, the number of electrons change. When nitrogen gains 3 electrons and sodium loses 1 electron, they end up having the same number of electrons (10).
D.) is incorrect. When elements ionize, the number of neutrons does not change. The only way two different elements could have the same number of neutrons is if at least one of the elements is an isotope. Isotopes are two or more atoms of the same element that differ in their amounts of neutrons.
Answer:
D.Lowering the temperature is the best option.
Explanation:
The value of equilibrium constants aren't changed with change in the pressure or concentrations of reactants and products in equilibrium. The only thing that changes the value of equilibrium constant is a change of temperature.
In the reaction below for example;
A + B <==>C+D
If you have moved the position of the equilibrium to the right (and so increased the amount of C and D), why hasn't the equilibrium constant increased?
Let's assume that the equilibrium constant mustn't change if you decrease the concentration of C - because equilibrium constants are constant at constant temperature. Why does the position of equilibrium move as it does?
If you decrease the concentration or pressure of C, the top of the Kc expression gets smaller. That would change the value of Kc. In order for that not to happen, the concentrations of C and D will have to increase again, and those of A and B must decrease. That happens until a new balance is reached when the value of the equilibrium constant expression reverts to what it was before.
It has 78 neutrons in a cesium
Explanation:
Electronic configuration of uranium is given below -
1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹⁰5s²5p⁶4f¹⁴5d¹⁰6s²6p⁶5f³6d¹7s2²
Effective nuclear charge (Z eff) = Atomic number (Z) - Shielding constant (S)
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Value of Shielding constant (S) can be calculated by using slater's rule :
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S = 1 (0.35) + 9 (0.85) + 81 (1.00)
S = 0.35 + 7.65 + 81.00
S = 89
So,
Zeff = Z - S
Zeff = 92 - 89
<u>
Zeff = 3
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Hence, Effective nuclear charge (Zeff) of uranium = <u>3
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5s electron is closest to the nucleus.
You first need to write the balanced chemical reaction for what is going on.
Ca(OH)₂+2HCl→2H₂O+CaCl₂
After you make the balanced chemical reaction, First you find the moles of HCl used. To do this multiply 0.0375L by 0.124M to get 0.00465mol HCl. Then you multiply 0.00465mol HCl by (1mol Ca(OH)₂)/(2mol HCl) to get 0.002325mol Ca(OH)₂. Finally to find concentration of Ca(OH)₂ used you divide 0.002325mol by 0.020L to get 0.116M Ca(OH)₂.
Therefore the concentration of the unknown solution of Ca(OH)₂ was 0.116M.
I hope this helps. Let me know if anything is unclear.
