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Semenov [28]
3 years ago
10

Which element contains four electrons in its third and outer main energy level? ​

Chemistry
1 answer:
UkoKoshka [18]3 years ago
6 0

Answer:

valence electrons

Explanation:

The valence electrons are the outer most electrons and the principal energy level in which they belong will vary for .

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A gas is initially at a pressure of 225 kPa and a temperature of 245 K in a container that is 4.5 L. If the gas is compressed to
Artyom0805 [142]
Use the ideal gas equation PV=nRT. You can compare before and after using P1V1/n1T1=P2V2/n2T2. Since the number of moles remains constant you can disregard moles from the equation and use pressure, volume and temp. Make sure your pressure is converted to atmospheres, your volume is in liters, and your temperature is in kelvins.
6 0
3 years ago
Which description is true of 0.02 M Ca(OH)2 if Ca(OH)2 completely dissociates in water? A. It’s a dilute strong acid. B. It’s a
Sphinxa [80]

Answer: B. It’s a dilute strong base.


Explanation:


1) Definition of acids and bases: as per Bronsted-Lowry model, an acid is a substance that donates hydrogen ions and a base is a substance that accepts hydrogen ions.

Ca(OH)₂ does not have hydrogen ions to donate, but it can accept hydrogen ions to form H₂O according to this equation: H⁺ + OH⁻ → H₂O.

Hence,  Ca(OH)₂ is a base.


2) Definition of strong base: a strong base is a base that dissociates completely into metallic and hydroxide ions in aqueous solutions, while a weak base dissociates partially.


Hence, Ca(OH)₂ is a strong base.


3) Definition of dilute: it refers to a solution meaning that the substance is not pure and the concentration is low. Since, the solution the Ca(OH)₂ is 0.02 M means that it is dilute.


Therefore, we have found that the description of 0.02 M Ca(OH)₂ is that is is a dilute strong base (option B).


5 0
3 years ago
Balance the following chemical reactions:
Tcecarenko [31]

1. 2Pb(NO₃)₂ → 2PbO + 4NO₂ + O₂

2. CH₄ + 2O₂ → CO₂ + 2H₂O

3. Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag

4. MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂

5. Pb(NO₃)₂ + 2NaCl → PbCl₂ + 2NaNO₃

1)

NaCl+AgNO_3=>NaNO_3+AgC\downarrow

2)

CuSO_4+Cu_2Cl_2\neq>

CuSO_4+Cu_2l_2\neq

4 0
3 years ago
Read 2 more answers
What is a possible quantum number set for an electron in the 2s orbital of a beryllium (Be) atom?
Artist 52 [7]

Answer is: 2,0,0,±1/2.

1) n = 1. The principal quantum number (n) is one of four quantum numbers which are assigned to each electron in an atom to describe that electron's state.

2) l = 0. The azimuthal quantum number is a quantum number for an atomic orbital that determines its orbital angular momentum and describes the shape of the orbital.

3) ml = 0. Magnetic quantum number specify orientation of electrons in magnetic field and number of electron states (orbitals) in subshells.

Magnetic quantum number (ml) specifies the orientation in space of an orbital of a given energy and shape . Magnetic quantum number divides the subshell into individual orbitals which hold the electrons, there are 2l+1 orbitals in each subshell.  

4) The spin quantum number, ms, is the spin of the electron; ms = +1/2 or -1/2.

7 0
3 years ago
Observando la siguiente reacción química: 3Fe + 4H2 O Fe3 O4 + H2(g) 4. Contesta ¿Por qué si se lleva a cabo en el recipiente ab
wolverine [178]

Answer:

La reacción se convierte en reversible porque en un recipiente cerrado el gas no escapa y puede reaccionar con el óxido

Explanation:

Basados en la reacción:

3Fe + 4H₂O → Fe₃O₄ + 4H₂(g)

<em>3 moles de hierro con 4 moles de agua producen 1 mol de óxido de hierro y 4 moles de hidrógeno (gas)</em>

Cuando la reacción se está produciendo con un recipiente abierto, todo el gas de hidrógeno está escapando a la atmósfera y no habrá forma de que reaccione con el óxido de hierro.

Pero, si el recipiente está cerrado, el hidrógeno no podrá escapar y podrá reaccionar con el óxido de hierro, así:

Fe₃O₄ + 4H₂(g) → 3Fe + 4H₂O

De esta manera,

<h3>la reacción se convierte en reversible porque en un recipiente cerrado el gas no escapa y puede reaccionar con el óxido</h3>
5 0
3 years ago
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