Answer:
A
Explanation:
To label an element correctly using a combination of the symbol, mass number and atomic number furnishes some important information about the element.
We can obtain these information from the element provided that correct labeling of the element is presented. Firstly, after writing the symbol of the element, the atomic number is placed as a subscript on the left while the mass number of the atomic mass is placed as a superscript on the same left.
Looking at the question asked, we have the element symbol in the correct position as Ca, with 42 also in the correct position which is the mass number. The third number which is 20 is thus the atomic number of the element.
Answer:
24.309 g/mol
Explanation:
To get the atomic mass, all we have to do is calculate with the masses of the three isotope, the real quantity present, taking account of the percent and then, do a sum of these three values. Like a pondered media.
For the first isotope:
23.99 * (78.99/100) = 18.95 g/mol
For the second isotope:
24.99 * (10/100) = 2.499 g/mol
For the last isotope:
25.98 * (11.01/100) = 2.86 g/mol
Now, let's sum all three together
AW = 18.95 + 2.499 + 2.86
AW = 24.309 g/mol
Answer:-
Oxygen gains electrons and is reduced.
Explanation:-
For this reaction the balanced chemical equation is
4Fe + 3O2 --> 2Fe2O3
When Oxygen is present as oxygen gas, the oxidation number of O is Zero since it is the only element present in Oxygen gas.
Similarly Iron is present in Fe with oxidation number Zero.
In the case of Fe2O3, Oxygen has the oxidation number -2 while Iron has +3.
So the oxidation number of Oxygen goes from Zero to -2.
Since the oxidation number decreases Oxygen is reduced.
Since reduction involves gain of electrons, Oxygen gains electrons.
<span>Chemical reaction: CH</span>₃COO⁻(aq) + H⁺(aq) ⇄ CH₃COOH(aq).
H⁺ is from HNO₃: HNO₃ → H⁺ + NO₃⁻.
<span>A buffer can
be defined as a substance that prevents the pH of a solution from changing by
either releasing or absorbing H</span>⁺ in a
solution.
Buffer is a solution
that can resist pH change upon the addition of an acidic or basic components
and it is able to neutralize small amounts of added acid or base, pH of
the solution is relatively stable.
The radius of the electron's or basically the energy level for which the electron is found orbiting the nucleus of he hydrogen atom, as the principal quantum number tells us primarily the energy level that the electron will be found, is it the 1st, 2nd, and 3rd. The other quantum numbers tells us more specifically as per the subshell of the main shell the electron is in, the spin of the electron etc.
