Which of the following of elements would have all four valence electrons
B, Si, As, Te
C, Si, Ge,Sn
O, S, Se, Te
Ga, Ge, As, Se

Answer:

A chemical change

Explanation:

From the observation, a chemical change has ensued.

A chemical change is one in which new kind of matter is formed. It is always accompanied by energy changes . This process is not easily reversible.

Answer:

B

Explanation:

D=S×T

=120km/h×4hrs

=480km

Answer:

the answer is b

Explanation:

this is the answer :)

Answer:

yes

Explanation:

Answer:

The best solution is Strong acid

Explanation:

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A solution that has a pH of 2 is a strong acid solution.

Explanation:

                            [tex]pH=-\log[H^+][/tex]

So, from this, we can conclude that solution with a pH of 2 which is less than 7, hence strong acidic solution.

Learn more about the pH of the solution here:

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in my opinion it's true!!!

Answer:

Percent yield = 90.9%

Explanation:

Given data:

Mass of CaCO₃ = 50.0 g

Mass of CO₂ produced = 20.0 g

Percent yield = ?

Solution:

Chemical equation:

CaCO₃ →  CaO + CO₂

Number of moles of CaCO₃:

Number of moles = mass/molar mass

Number of moles = 50.0 g/ 100.1 g/mol

Number of moles = 0.5 mol

Now we will compare the moles of CO₂ with CaCO₃.

                      CaCO₃          :        CO₂

                          1                :           1

                       0.5               :          0.5

Mass of CO₂: Theoretical yield

Mass = number of moles × molar mass

Mass = 0.5 mol × 44 g/mol

Mass = 22 g

Percent yield:

Percent yield = ( actual yield / theoretical yield ) × 100

Percent yield = (20.0 g/ 22.0 g) × 100

Percent yield = 0.909 × 100

Percent yield = 90.9%

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:

10 degrees C

Explanation:

Answer:

vitreous

Explination:

The vitreous is the gel-like fluid that fills your eye. It's full of tiny fibers that attach to your retina (the light-sensitive layer of tissue at the back of the eye). As you get older, the fibers of your vitreous pull away from the retina.

Answer:

The vitreous

Explanation:

Answer:

Lateral Inversion

Explanation:

Answer:

there is nothing follow that

Explanation:

Answer:

Explanation:

Baby pigs, dolphins, bats and elephants all drink milk! Because the babies rely on their mother's milk to live, the mammal mommies have to care for their young. ... Through copying their mothers, baby mammals learn everything they need to survive

Answer:

by be young

Explanation:

wow just use you brain

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:

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:

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:

Acid

Explanation:

acid

Answer:

An acid

Explanation:

H2OSO4 is Sulfuric Acid

Answer:

220.8L

Explanation:

Given parameters:

Initial volume  = 50L

Initial temperature = 15°C  = 288K

Initial pressure = 640mmHg

Final temperature  = 45°C  = 318K

Final pressure  = 160mmHg

Unknown:

Final volume  = ?

Solution:

Using the combined law;

        [tex]\frac{p_{1}v_{1} }{T_{1} }[/tex]  = [tex]\frac{p_{2}v_{2} }{T_{2} }[/tex]  

p,v and T are pressure, volume and Temperature

    [tex]\frac{640 x 50}{288}[/tex]  = [tex]\frac{160 x v_{2} }{318}[/tex]

     160 x 288 x v₂ = 640 x 50 x 318

                         v₂ = 220.8L

a. pH=2.07

b. pH=3

c. pH=8

pH=-log [H⁺]

a) 0.1 M HF Ka = 7.2 x 10⁻⁴

HF= weak acid

[tex]\tt [H^+]=\sqrt{Ka.M}\\\\(H^+]=\sqrt{7.2.10^{-4}\times 0.1}\\\\(H^+]=8.5\times 10^{-3}\\\\pH=3-log~8.5=2.07[/tex]

b) 1 x 10⁻³ M HNO₃

HNO₃ = strong acid

[tex]\tt pH=-log[1\times 10^{-3}]=3[/tex]

c) 1 x 10⁻⁸ M HCl

[tex]\tt pH=-log[1\times 10^{-8}]=8[/tex]

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.

To find more on ionic compounds, refer here:

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Answer:

It's D

Explanation:

Explanation:

2CO2 + 3H2O + 4Br2

C = 2

O = 5

H = 6

Br =8

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

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:

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

Answer:

The asnswer is c

Explanation:

Gope it helps

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:

C. Iron oxide is a mixture of iron and oxygen

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