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2 years ago

What is the difference between the number of electrons in an atom of selenium?

Chemistry

1 answer:

azamat2 years ago

3 0

Explanation:

Supposing we have to find the difference between the number of electrons in Selenium and Aluminium.

Well, electrons can be transformed to an atomic number, so if SE is 34, that means it has 34 electrons. AI has an atomic number of 13, which means it has 13 electrons. So the difference is that more electrons than AI are available from SE.

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He distance from Earth to the North Star is about 430 light-years. Which of the following statements describes why scientists us

garri49 [273]

Answer:

Explanation:

because the rest don’t make any sense

8 0

2 years ago

A 7.0 L sample of gas begins at 2.5 atm and 320. K. What is the new pressure if the temperature is changed to 273 K and the volu

enyata [817]

Answer:

2.1 atm

Explanation:

We are given the following variables to work with:

Initial pressure (P1): 2.5 atm

Initial temperature (T1): 320 K

Final temperature (T2): 273 K

Constant volume: 7.0 L

We are asked to find the final pressure (P2). Since volume is constant, we want to choose a gas law equation that relates initial pressure and temperature to final pressure and temperature. Gay-Lussac's law does this:

$\frac{P_{1}}{T_1} =\frac{P_{2}}{T_2} \\$

We can rearrange the law algebraically to solve for $P_{2}$ .

${P_{2}} =\frac{(T_2)(P_{1} )}{T_1} \\$

Substitute your known variables and solve:

$P_2 = \frac{273K(2.5atm)}{320K} = 2.1 atm$

4 0

2 years ago

An open flask sitting in a lab refrigerator looks empty, but it is actually filled with a mixture of gases called air. If the fl

ira [324]

Answer:

9.39 × 10²² molecules

Explanation:

We can find the moles of gases (n) using the ideal gas equation.

P . V = n . R . T

where,

P is the pressure (standard pressure = 1 atm)

V is the volume

R is the ideal gas constant

T is the absolute temperature (standard temperature = 273.15 K)

$n=\frac{P.V}{R.T} =\frac{1atm.3.50L}{(0.08206atm.L/mol.K).273.15K} =0.156mol$

There are 6.02 × 10²³ molecules in 1 mol (Avogadro's number). Then,

$0.156mol.\frac{6.02\times10^{23}molecules}{mol} =9.39\times10^{22}molecules$

4 0

3 years ago

"how is the stomach lining protected from the strongly acidic ph of its contents?"

SIZIF [17.4K]

It is protected by a mucus layer formed on the surface regularly that ressist ph values.If it isn't formed our body will eat itself.

6 0

3 years ago

A chemist wants to calculate the amount of heat that is absorbed by a sample of copper as it is melted. Which constant should sh

34kurt

The constant used for the absorption of heat by the sample in melting is $+\Delta H_{fus}$ . Thus, option A is correct.

The chemical reaction has been defined as the energy in which the energy has been released or absorbed for the breaking of bonds in the reactants and the formation of product.

<h3>Constant for energy absorbed</h3>

The energy has been absorbed in the melting of the copper sample. Thus, the sample has been converted from the solid to the liquid state.

The change in energy with the conversion in solid and liquid state has been termed as heat of fusion.

The energy has been absorbed by the system, thus it has been marked with the positive sign.

Therefore, $+\Delta H_{fus}$ has been the constant used for the absorption of heat by the sample in melting. Thus, option A is correct.

Learn more about melting sample, here:

brainly.com/question/8828503

8 0

2 years ago