<u>Answer:</u> The correct answer is Option A.
<u>Explanation:</u>
Standard enthalpy of formation is the change in enthalpy of one mole of a substance present at the standard state that is 1 atm of pressure and 298 K of temperature. The substance is formed from its pure elements under the same conditions.
We are given a chemical compound having chemical formula 
This compound is formed by the combination of calcium, nitrogen and oxygen elements.
The chemical equation for the formation of from the components in their standard states follows:
Hence, the correct answer is Option A.
Answer:
- <em>The two-dimensional set of points that has no beginning or end is described by the undefined geometric term</em> <u>plane.</u>
Explanation:
There are three <em>undefined terms</em><em> in geometry</em>:
They are referred as undefined terms because they are not defined in a formal way, i.e. using mathematically defined words. At the end these terms are abstractions (ideas).
The point has no dimensions, it can be represented by the tip of a sharp pencil.
The line is referred as an infinite set of joined points that extend indefinitely in one direction (from right to left, from north to south), so it has one dimension. The intersection of of two perpendicular walls is an example of what a line is.
Finally, the term to which the question is referred is the plane: an infinite set of joined points that extends in two dimensions. An example of plane is the surface of quite water. The plane does not have depth, only extension; that is why it has only two dimensions.
So, you should remember: points do not have dimensions, lines have one dimension, and planes have two dimensions.
Given two electrons with charge of 1.5x10^-10 m
The electostatic force between them is determined by this formula:
F = kq1q2/r^2
where
k = 9x10^9
q1 = q2 = 1.5x10^-10
r = 2.82x10^-15
F = 9x10^9 * (1.5x10^-10)^2 / 2.82x10^-15
= 71808.51
Answer:
a. the solution will be weakly basic.
b. Greater than 7 because CN⁻ is a stronger base than NH₄⁺ is an acid.
Explanation:
a. The fluoride ion (F⁻) reacts with water thus:
F⁻ + H₂O → HF + OH⁻
That means that fluoride ions produce OH⁻ ions in solution doing <em>the solution will be weakly basic.</em>
b. The acidic equilibrium of NH₄⁺ is:
NH₄⁺ ⇄ NH₃ + H⁺ with a ka of 5,6x10⁻¹⁰.
The basic equilibrium of CN⁻ is:
CN⁻ + H₂O → HCN + OH⁻ with a kb of 2x10⁻⁵
That means that the production of OH⁻ from CN⁻ is higher than production of H⁺ from NH₄⁺. The CN⁻ is a stronger base than NH₄⁺ is an acid.
Thus, the pH of a salt solution of NH₄CN would be <em>Greater than 7 because CN⁻ is a stronger base than NH₄⁺ is an acid.</em>
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I hope ot helps!
About 2,500 grams Ans balkfdoaks;
