Which element rarely reacts because it has 8 electrons in its outer shell?
A. Bromine
B. Xenon
C. Arsenic
D. Potassium

Answer:

C. He

Explanation:

When lithium is ionized, its new electronic configuration is the same as that of a helium atom.

 Lithium is made up of 3 electrons with a configuration of:

                     2, 1

it has 1 electron in its outermost shell.

As a metal lithium will prefer to lose an electron due to its electropositivity.

    On losing an electron, it will have 2 electrons remaining

Now, Helium has 2 electrons and this makes it similar to Lithium that has lost one electron.

This makes Lithium isoelectronic with Helium.  

Answer:

It's D

Explanation:

Answer:

Atomic number 29

Atomic mass 63.546 g.mol -1

Electronegativity according to Pauling 1.9

Density 8.9 g.cm-3 at 20°C

Melting point 1083 °C

Copper has a melting point of 1083.4 +/- 0.2°C, boiling point of 2567°C, specific gravity of 8.96 (20°C), with a valence of 1 or 2. Copper is reddish colored and takes a bright metallic luster. It is malleable, ductile, and a good conductor of electricity and heat.

Answer:

just watch the video, what does it start with, write that down for each trial, then what does it end with, then starting mass - ending mass is the change mass

Answer:

D

Explanation:

Units and directions

Answer:

create and destroyed

Explanation:

its just simple science

Answer:

Create bonds

Broken

Explanation:

Energy is required to created bonds in a molecule and released when bonds are broken.

Energy is needed in chemical reactions to do work.

Answer:

discupaeu não sei

um belo dia abençoado

Answer:

Explanation:

The percentage error of a certain measurement can be found by using the formula

[tex]P(\%) = \frac{error}{actual \: \: number} \times 100\% \\[/tex]

actual mass = 24.3

error = 24.3 - 14.7 = 9.6

We have

[tex]p(\%) = \frac{9.6}{24.3} \times 100 \\ = 39.506172839...[/tex]

We have the final answer as

Hope this helps you

Answer:

3 electrons

Explanation:

That means there are 3 electrons in a lithium atom. Looking at the picture, you can see there are two electrons in shell one and only one in shell two.

Answer:

4.4 L

Explanation:

Given data:

Initial number of mole = 0.55 mol

Initial volume = 2.0 L

Final volume = ?

Final number of moles = 1.20 mol

Temperature and pressure = constant

Solution:

Formula:

V₁/n₁   = V₂/n₂

V₂ = V₁×n₂/n₁  

V₂ = 2.0 L ×1.20 mol/ 0.55 mol

V₂ = 2.4 L.mol / 0.55 mol

V₂ = 4.4 L

The volume of the gas is 31.3 L.

Using the formula;

PV = nRT

P = pressure of the gas

V = volume of the gas

n = Number of moles of the gas

R  gas constant

T = temperature

To obtain the volume;

V = nRT/P

V = 1.20 mol * 0.082 atmLmol-1K-1 * 318 K/7.0 atm

V = 31.3 L

Learn more about volume:

Answer:

False

Explanation:

There is a direct relationship between wave frequency and energy...

The higher the frequency, the higher the energy

alternatively, the lower the frequency, the lower the energy

Answer:

there is nothing follow that

Explanation:

Answer:

The atmosphere and Earth's interior are layered by density. ... Earth's core, at its center, is denser than its crust. The lowest layer of the atmosphere is denser than the upper layer. Earth's liquid metal outer core has convection, which generates the magnetic field.

Explanation:

hope this helps!

Answer:

Gravity pulls denser materials to the center of the earth, so it is basically a sphere of wrapping paper that gets denser and denser the more you unwrap the layers. The core is the most dense, and the crust is the least dense.

Hope This Helps! :) Plz Give Brainliest!

Answer:

Lateral Inversion

Explanation:

Answer:

Gold is an element even when it is in a solution

Answer:

10 degrees C

Explanation:

Explanation:

2CO2 + 3H2O + 4Br2

C = 2

O = 5

H = 6

Br =8

Answer:

22.95g

Explanation:

Given parameters:

Percentage by mass of silver in silver iodide  = 45.9%

Mass of silver iodide given  = 50g

Unknown:

Mass of silver in silver iodide  = ?

Solution:

The formula of the compound is;

 Silver iodide  = AgI

       Since the percentage by mass of silver in the compound is 45.9%;

 Mass of silver  = percentage by mass of silver x mass of AgI

 Mass of silver  = [tex]\frac{45.9}{100}[/tex] x 50  = 22.95g

Answer:

6.19⋅109ng

Explanation:

The first thing to do here is to determine the mass in grams of 2.33⋅1020 atoms of oxygen.

To do that, use Avogadro's number to convert the number of atoms to moles, the molar mass of oxygen to convert the moles to grams.

So, Avogadro's number, which acts as the definition of a mole, tells you that in order to have one mole of oxygen, you need to have 6.022⋅1023 atoms of oxygen.

In your case, the sample will be equivalent to

2.33⋅1020 atoms of O ⋅1mole O

                                    6.022⋅1023 atoms of O   =3.869⋅10−4 moles O

Now, oxygen has a molar mass of 15.9994 g mol−1 as listed in the Periodic Table of Elements

This means that your sample will have a mass of

3.869⋅10−4 moles O   ⋅15.9994 g

                                       1 mole O           =6.190⋅10−3g

Finally, you can convert the mass from grams to nanograms by using the conversion factor  

1 g=109ng

You will end up with

6.190⋅10−3g ⋅109ng

                        1g=6.19⋅106ng

meaning The answer is rounded to three sig figs.

Answer:

yes

Explanation:

Answer:

yes i can anwser

Explanation:

Answer:

b is the answer .............

Answer:

The asnswer is c

Explanation:

Gope it helps

Mass of oxygen gas produced : 14.08 g

Reaction

2H₂O(l)⇒2H₂(g)+O₂(g)

mol of H₂O (MW=18 g/mol) :

[tex]\tt \dfrac{20}{18}=1.1[/tex]

mol O₂ :

[tex]\tt \dfrac{1}{2}\times 1.1=0.55[/tex]

mass O₂ (theoretical) :

[tex]\tt 0.55\times 32=17.6~g[/tex]

mass O₂ (actual) :

[tex]\tt =\%yield\times theoretical\\\\=0.8\times 17.6=14.08[/tex]

Answer:

Thickness, length, and temperature

Explanation:

The resistance of a long wire is greater than the resistance of a short wire because electrons collide with more ions as they pass through. The relationship between resistance and wire length is proportional. A thicker wire simply has more 'lanes' on the go at once. A higher current for a given voltage means a lower resistance. The thicker wire has a lower resistance than the thinner wire does. The resistance of a wire decreases with increasing thickness. The resistance of a metal conductor is due to collisions between the free electrons of the electric current and the metal ions of the wire. If the temperature of a metal conductor increases, the ions of the metal vibrate more vigorously. The resistance of an NTC thermistor decreases with increasing temperature.

The resistance of a wire depends on the following three properties of a wire, thickness, length, temperature.

The resistance of a wire is the opposition to the flow of current offered by the wire.

The resistance of a wire depends on the flowing;

R = ρL/A

where;

Thus, the resistance of a wire depends on the following three properties of a wire, thickness, length, temperature.

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Explanation:

The molar mass of a substance is the mass in grams of one mole of the substance. In a compound, add the atomic masses of the components.

 HCl

 Atomic mass of H  = 1g/mol,  Cl = 35.5g/mol

   HCl  = (1 + 35.5) = 36.5g/mol

 ZnF₂

Atomic mass of Zn  = 65.4g/mol, F = 19g/mol

      ZnF₂  = 65.4 + 2(19) = 103.4g/mol

 K₂CO₃

   Atomic mass of K = 39, C  = 12, O = 16

    K₂CO₃  = 2(39) + 12 + 3(16)  = 138g/mol

 FePO₄

Atomic mass of Fe = 55.8, P = 31, 0 = 16

 FePO₄ = 55.8 + 31 + 4(16) = 150.8g/mol

Cu₂S

  Atomic mass of Cu = 63.5g/mol, S = 32

    Cu₂S = 2(63.5) + 32 = 159g/mol

Each term in the series represents a sinusoidal component with a frequency of (kπ/4) and an amplitude of 4.

To express the given periodic signal x(t) in the form x(t) = ∑[k=0 to infinity] A_k cos(w_kt + ϕ_k),\

we can use the formula for the Fourier series representation of a periodic signal.

1. First, let's find the values of A_k, w_k, and ϕ_k using the given Fourier series coefficients.

The given coefficients are:

a_1 = a_-1* = j

a_5 = a_-5 = 2

Since x(t) is real-valued, the coefficients for negative frequencies (a_-k) are the complex conjugates of the coefficients for positive frequencies (a_k).

From the given coefficients, we can determine the values of A_k:

A_1 = a_1 + a_-1 = j + conj(j) = j - j = 0

A_5 = a_5 + a_-5 = 2 + conj(2) = 2 + 2 = 4

Since the fundamental period T is 8, the fundamental frequency is ω_0 = 2π/T = 2π/8 = π/4.

The values of w_k can be determined as:

w_0 = 0

w_k = k * w_0 = k * (π/4) for k ≠ 0

The values of ϕ_k can be determined as:

ϕ_0 = 0

ϕ_k = arg(a_k) for k ≠ 0

2. Now, let's express x(t) in the desired form using the determined values.

x(t) = A_0 cos(w_0t + ϕ_0) + ∑[k=1 to infinity] A_k cos(w_kt + ϕ_k)

Substituting the values we found:

x(t) = 0 cos(0t + 0) + ∑[k=1 to infinity] 4 cos((kπ/4)t + arg(a_k))

Simplifying:

x(t) = ∑[k=1 to infinity] 4 cos((kπ/4)t + arg(a_k))

This is the expression of x(t) in the desired form.

Remember that the series is infinite, so it includes all integer values of k.

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Answer:

B. increase the temperature

Explanation:

Answer:

1) Zn(s) + 2HCl(aq) --> ZnCl2(aq) + H2(g)

You would see the reaction forming bubbles vigorously. Hydrogen gas is produced in the process.

Answer: I'm willing to help you find the formula for that ionic crystal but, I can't see anything.

The ionic crystal contains a total of 6 Ba atoms and 6 oxygen atoms. Hence they are in 1 : 1 ratio and the formula of the ionic compound is BaO.

Ionic compounds are formed between metals and non-metals. Ionic bond is formed by the lose of electrons from the metals to the nonmetals. The chemical formula of the ionic compounds are written with the cationic symbol first.

The given ionic crystal is formed with barium and oxygen atoms. Valency of barium is 2 and that of oxygen is also 2. Thus, barium loses two electrons to oxygen forming BaO.

The given crystal lattice consists of 3 barium atoms and 3 oxygen atoms in front face and 3 Ba and 3 o in back face also. Thus, both are 6. They are in the ratio of 1 : 1. Hence, the compound is named as BaO.

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