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2 years ago

Explain why the sign of the slope of a regression line must be thesame as the sign of the correlation coeffi cient.

Chemistry

2 answers:

Umnica [9.8K]2 years ago

8 0

Answer:

The calculation of a standard deviation involves taking the positive square root of a nonnegative number. As a result, both standard deviations in the formula for the slope must be nonnegative. ... Therefore the sign of the correlation coefficient will be the same as the sign of the slope of the regression line.

Explanation:

have a nice day

MAXImum [283]2 years ago

6 0

Answer:

Explanation:

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Be sure to answer all parts. What is the [H3O+] and the pH of a buffer that consists of 0.26 M HNO2 and 0.89 M KNO2? (K, of HNO2

Aleksandr-060686 [28]

Answer : The $H_3O^+$ ion concentration is, $1.12\times 10^{-3}M$ and the pH of a buffer is, 2.95

Explanation : Given,

$K_a=7.1\times 10^{-4}$

Concentration of $HNO_2$ (weak acid)= 0.26 M

Concentration of $KNO_2$ (conjugate base or salt)= 0.89 M

First we have to calculate the value of $pK_a$ .

The expression used for the calculation of $pK_a$ is,

$pK_a=-\log (K_a)$

Now put the value of $K_a$ in this expression, we get:

$pK_a=-\log (7.1\times 10^{-4})$

$pK_a=4-\log (7.1)$

$pK_a=3.15$

Now we have to calculate the pH of the solution.

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

$pH=pK_a+\log \frac{[KNO_2]}{[HNO_2]}$

Now put all the given values in this expression, we get:

$pH=3.15+\log (\frac{0.89}{0.26})$

$pH=2.95$

The pH of a buffer is, 2.95

Now we have to calculate the $H_3O^+$ ion concentration.

$pH=-\log [H_3O^+]$

$2.95=-\log [H_3O^+]$

$[H_3O^+]=1.12\times 10^{-3}M$

The $H_3O^+$ ion concentration is, $1.12\times 10^{-3}M$

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2 years ago

HELP!!!! A glass flask containing 100 milliliters of water is sealed with a rubber stopper and placed on a burner. After a while

kondor19780726 [428]

Answer: A closed system, because energy can enter or leave the container, but the water molecules cannot

Explanation:

Open system: In this system energy and matter both have access to their surroundings beyond the boundaries of system. .

Closed system :In this type system only energy has an access to its surroundings beyond the boundaries of system but not matter.

Isolated system:In this type system exchange of both energy and matter are restricted to move outside the boundaries of system.

According to question, the system given is a closed system because energy is transferred from the burner to glass flask and from the glass flask to the water (matter). But water molecules are only getting condensed on the inside surface of the flask that is exchange of matter beyond the boundaries of the system is restricted. Hence, closed system ,A closed system, because energy can enter or leave the container, but the water molecules cannot.

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Select the compound that is most likely to increase the solubility of ZnSe when added to water.NaCnMgBr2NaClKClO4

vlada-n [284]

Answer:

NaCl.

Explanation:

In the solution, ZnSe ionizes to $Zn^2^+$ and $Se^2^-$ . Following reaction represents the ionization of ZnSe in solution -

$ZnSe$ ⇄ $Zn^2^+ + Se^2^-$

As we want to increase the solubility of ZnSe, we must decrease the concentration of dissociated ions so that the reaction continues to forward direction.

If we add NaCl to this solution, then we have $Na^+$ and $Cl^-$ in the solution which will be formed by the ionization of NaCl.

Now, $Zn^2^+$ in the solution will react with two $Cl^-$ ions to form $ZnCl_2$ as follows -

$Zn^2^++2Cl^-$ ⇄ $ZnCl_2$

Due to this reaction the concentration of $Zn^2^+$ will decrease in the solution and more ZnSe can be soluble in the solution.

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