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3 years ago

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What percentage of the sun is composed of hydrogen?

1 answer:

den301095 [7]3 years ago

3 0

Your answer will be 75%

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slader Consider the following reactions: A. uranium-238 emits an alpha particle; B. plutonium-239 emits an alpha parti- cle; C.

pishuonlain [190]

<u>Answer:</u>

<u>For A:</u> The equation is $_{92}^{238}\textrm{U}\rightarrow _{90}^{234}\textrm{Th}+_2^4\alpha$

<u>For B:</u> The equation is $_{94}^{239}\textrm{Pu}\rightarrow _{92}^{235}\textrm{U}+_2^4\alpha$

<u>For C:</u> The equation is $_{90}^{239}\textrm{Th}\rightarrow _{91}^{235}\textrm{Pa}+_{-1}^0\beta$

<u>Explanation:</u>

Alpha decay process is the process in which nucleus of an atom disintegrates into two particles. The first one which is the alpha particle consists of two protons and two neutrons. This is also known as helium nucleus. The second particle is the daughter nuclei which is the original nucleus minus the alpha particle released.

$_Z^A\textrm{X}\rightarrow _{Z-2}^{A-4}\textrm{Y}+_2^4\alpha$

Beta decay process is defined as the process the neutrons get converted into an electron and a proton. The released electron is known as the beta particle. In this process, the atomic number of the daughter nuclei gets increased by a factor of 1 but the mass number remains the same.

$_Z^A\textrm{X}\rightarrow _{Z+1}^A\textrm{Y}+_{-1}^0\beta$

<u>For A:</u> Uranium-238 emits an alpha particle

The nuclear equation for this process follows:

$_{92}^{238}\textrm{U}\rightarrow _{90}^{234}\textrm{Th}+_2^4\alpha$

<u>For B:</u> Plutonium-239 emits an alpha particle

The nuclear equation for this process follows:

$_{94}^{239}\textrm{Pu}\rightarrow _{92}^{235}\textrm{U}+_2^4\alpha$

<u>For C:</u> Thorium-239 emits a beta particle

The nuclear equation for this process follows:

$_{90}^{239}\textrm{Th}\rightarrow _{91}^{235}\textrm{Pa}+_{-1}^0\beta$

6 0

3 years ago

Calculate the Standard Enthalpy of the reaction below:

Norma-Jean [14]

Answer:

(we use hess's law) it is so simple but the second reaction is not correct please right it

6 0

3 years ago

When a aqueous solution of a certain acid is prepared, the acid is dissociated. Calculate the acid dissociation constant of the

stepan [7]

<h2> $K_a$ = $\dfrac{[H^{+}] [A^{-}]}{[HA]}$ </h2>

Explanation:

When an aqueous solution of a certain acid is prepared it is dissociated is as follows-

${\displaystyle {\ce {HA$ ⇄ ${H^+}+{A^{-}}} }}$

Here HA is a protonic acid such as acetic acid, $CH_3COOH$

The double arrow signifies that it is an equilibrium process, which means the dissociation and recombination of the acid occur simultaneously.

The acid dissociation constant can be given by -

$K_a$ = $\dfrac{[H^{+}] [A^{-}]}{[HA]}$

The reaction is can also be represented by Bronsted and lowry -

$\\{\displaystyle {\ce {{HA}+ H_2O}$ ⇄ $[H_3O^+] [A^-]$

Then the dissociation constant will be

$K_a$ = $\dfrac{[H_3O^{+}] [A^{-}]}{[HA]}$

Here, $K_a$ is the dissociation constant of an acid.

6 0

3 years ago

Two closed vessels contain chlorine gas at the same conditions of temperature and

wariber [46]

Answer:12 mol

Explanation: both vessels are at the same temp and pressure (and the pressure is low and/or the temperature high).

6.7mol per 1.3L = 6.7/1.3 mol/L

so in 2.33L = 6.7*2.33/1.3 = 12 mol

8 0

2 years ago

Which would be an example of a compound?<br> oxygen<br> carbon dioxide<br> sand<br> carbon

GenaCL600 [577]

Answer:

carbondioxide is an example of compound.

4 0

3 years ago