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Which best describes an element?

A. elements are chemicals that are pure substance held together by chemical bonds

B. elements are mixtures of protons, neutrons, and electrons in different combination

C. elements are chemicals that are pure substances represented by symbols that have at least one capital letter

D. elements that are chemicals that are formed when temperature change happens or a precipitate forms

Explanation:

U need to draw the graph first and make a line at 17 pennies, where the line of 17 pennies and your graph meet is the mass of it(at y axis)

Answer:

k Nishant

Explanation:

i don't know sorry but u can search in google

Answer:

Magnetic forces are non contact forces; they pull or push on objects without touching them. Magnets are only attracted to a few 'magnetic' metals and not all matter. Magnets are attracted to and repel other magnets.

Hope this helps!!!

Explanation:

Answer:

I'm on the exact same queston

Answer:

The test variable (independent variable) controls the outcome variable (dependent variable)

Explanation:

its right on study island

Answer:

D - Nucleus to Cell

Explanation:

Hope it helps!!

:D

Answer:

We are given:

mass of the block = 3500 grams

volume of the block = 1000 mL

Finding the density:

Density = mass of the object (in grams) / volume of the object (in mL)

Density = 3500 / 1000

Density = 3.5 g / mL

Answer:(trick question) once the salt has dissolve  in the water it is no longer visible

Thank you! have an amazing day.

Analysing the question:

To calculate the density of a material, we need its mass and volume

We are given:

Mass of sample = 21 grams

dimensions of the sample = 1 * 1 * 2 = 2 cm³

Calculating the density:

Density = Mass of sample / volume of sample

Replacing the variables

Density = 21 / 2

Density  = 10.5 g / cm³

Determining the Material:

From the table provided, we can see that the density of Silver is 10.5 g/cm³

Therefore, the material is Silver

Answer:

A. exist in fixed amounts or available in limited supplies

Explanation:

Answer:

A

Explanation:

Answer:

Explanation:

The volume of a substance when given the density and mass can be found by using the formula

[tex]volume = \frac{mass}{density} \\ [/tex]

From the question

mass = 15.5 g

density = 6.89 g/mL

We have

[tex]volume = \frac{15.5}{6.89} \\ = 2.249637155...[/tex]

We have the final answer as

Hope this helps you

Answer:

Sorry I do not know the answer but I do know its not c (pressure)

Explanation:

I took a quiz with that question and I got it wrong my other guess is air density though

Answer:

Wind Speeds

Explanation:

im awnsering late cuz i need pointsss

Answer:

Invasive species are an organism that causes ecological or economic harm in a new environment where it's not native.

Explanation:

An invasive species can harm both the natural resources in the ecosystem as well it threaten the human use of these resources and invasive species can be introduced to a new area via the ballast water of oceangoing ships, intentional and accidental releases of aquaculture species, aquarium specimens or bait, and etc.

Invasive species is capable of causing extinctions to native plants and animals, reducing biodiversity, competing with native organisms for limited resources, and altering habitats. This can also result a huge economic impacts and fundamental disruptions of coastal and the great lakes of the ecosystems.

I hope it helps you.

Answer:

blocks 1 and 2 the rhdh huff hgfhh5

Answer:

The elements with completely filled shells are classified as noble gases

That is why we only see noble gases on the rightmost corner of the periodic table, it is because they have the maximum number of electrons in a shell

Examples of noble gases

Helium , Neon , Argon and Krypton are some examples of noble gases

Answer:

Explanation:

I JUST TOOK THE TEST!

Answer:

See explanation

Explanation:

A popular experiment that describes the effect of heat on the position of equilibrum is the change of colour when copper II chloride is heated.

As the solution is heated, it's colour changes from blue to green, this implies the the colour change (blue to green) is an endothermic process (equilibrum position shifts to the right with increase in temperature)

The equilibrum is represented by the equation;

[Cu(H2O)6]^2+(aq) + 4Cl^-(aq)<------>[CuCl4]^2-(aq) + 6H2O(l) ∆H=positive

The equilibrium mixture undergoing cooling or heating have colour changes. The temperature affects the colour of the products formed and the forward reaction is endothermic.

In the reaction copper (II) chloride or [tex]\rm CuCl_{4}[/tex] is the main species. The heat or the temperature affects the colour formation of copper (II) chloride as the equilibrium change affects the colouration of the product.

The heating of the solution affects the colour change from blue to the green of the reactant to products and the forward reaction shifts the equilibrium towards the right when the temperature is increased and is an endothermic reaction.

The reaction at the equilibrium can be shown as,

[tex]\rm [Cu(H_{2}O)_{6}]^{2+} (aq) + 4Cl^{-} (aq) \Leftrightarrow [CuCl_{4}]^{2-}(aq) + 6H_{2}O(l), \Delta H=positive[/tex]

Therefore, temperature changes the colouration and the forward reaction is an endothermic reaction.

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Answer:

1.3x10⁻⁸ mol/L

Explanation:

0.0013μmol, Calculate concentration in mol/L

To obtain concentration in mol/L we need to convert the μmoles to moles and mL to liters:

Moles silver(II) oxide:

0.0013μmol × (1mol / 1x10⁶μmol) = 1.3x10⁻⁹ moles

Liters solution:

100mL * (1L / 1000mL) = 0.1L

That means concentration in mol/L is:

1.3x10⁻⁹ moles / 0.1L =

Answer:

[tex]\%\ Error = 21.5\%[/tex]

Explanation:

Given

[tex]Measured = 24.5[/tex]

[tex]Actual = 31.2[/tex]

Required

Determine the percentage error

First, we need to determine the difference in the measurement

[tex]Difference = |Actual - Measured|[/tex]

[tex]Difference = |31.2 - 24.5|[/tex]

[tex]Difference = |6.7|[/tex]

[tex]Difference = 6.7[/tex]

The percentage error is calculated as thus:

[tex]\%\ Error = \frac{Difference * 100\%}{Actual}[/tex]

[tex]\%\ Error = \frac{6.7 * 100\%}{31.2}[/tex]

[tex]\%\ Error = \frac{670\%}{31.2}[/tex]

[tex]\%\ Error = 21.4743589744\%[/tex]

[tex]\%\ Error = 21.5\%[/tex] approximated

Answer: The percent yield of this combination reaction is 41.3 %

Explanation : Given,

Mass of [tex]Na[/tex] = 5.0 g

Mass of [tex]Cl_2[/tex] = 10.0 g

Molar mass of [tex]Na[/tex] = 23 g/mol

Molar mass of [tex]Cl_2[/tex] = 71 g/mol

First we have to calculate the moles of [tex]Na[/tex] and [tex]Cl_2[/tex].

[tex]\text{Moles of }Na=\frac{\text{Given mass }Na}{\text{Molar mass }Na}[/tex]

[tex]\text{Moles of }Na=\frac{5.0g}{23g/mol}=0.217mol[/tex]

and,

[tex]\text{Moles of }Cl_2=\frac{\text{Given mass }Cl_2}{\text{Molar mass }Cl_2}[/tex]

[tex]\text{Moles of }Cl_2=\frac{10.0g}{71g/mol}=0.141mol[/tex]

Now we have to calculate the limiting and excess reagent.

The balanced chemical equation will be:

[tex]2Na+Cl_2\rightarrow 2NaCl[/tex]

From the balanced reaction we conclude that

As, 2 mole of [tex]Na[/tex] react with 1 mole of [tex]Cl_2[/tex]

So, 0.217 moles of [tex]Na[/tex] react with [tex]\frac{0.217}{2}=0.108[/tex] moles of [tex]Cl_2[/tex]

From this we conclude that, [tex]Cl_2[/tex] is an excess reagent because the given moles are greater than the required moles and [tex]Na[/tex] is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of [tex]NaCl[/tex]

From the reaction, we conclude that

As, 2 mole of [tex]Na[/tex] react to give 2 mole of [tex]NaCl[/tex]

So, 0.217 mole of [tex]HCl[/tex] react to give 0.217 mole of [tex]NaCl[/tex]

Now we have to calculate the mass of [tex]NaCl[/tex]

[tex]\text{ Mass of }NaCl=\text{ Moles of }NaCl\times \text{ Molar mass of }NaCl[/tex]

Molar mass of [tex]NaCl[/tex] = 58.5 g/mole

[tex]\text{ Mass of }NaCl=(0.217moles)\times (58.5g/mole)=12.7g[/tex]

Now we have to calculate the percent yield of this reaction.

Percent yield = [tex]\frac{\text{Actual yield}}{\text{Theoretical yield}}\times 100[/tex]

Actual yield = 5.24 g

Theoretical yield = 12.7 g

Percent yield = [tex]\frac{5.24g}{12.7g}\times 100[/tex]

Percent yield = 41.3 %

Therefore, the percent yield of this combination reaction is 41.3 %

Answer:

Mass = 46 g

Explanation:

Given data:

Number of moles of NO = 1.0 mol

Amount of O₂ = excess

Mass of NO₂ formed = ?

Solution:

Chemical equation:

2NO + O₂    →    2NO₂

Now we will compare the moles of No with NO₂.

                  NO           :           NO₂

                    2            :            2

                     1            :           1

Mass of NO₂ in gram:

Mass = number of moles × molar mass

Mass = 1 mol ×46 g/mol

Mass = 46 g

Answer:

The structure of the atom

Answer:

The number 872 would be written as,

8.72× 10²

Explanation:

Scientific notation is used to express the large value in short form.

The number in scientific notation have two parts.

First part:

The digits (decimal point will place after first digit)

Second part:

× 10 ( the power which put the decimal point where it should be)

For example the number 872 would be written as

8.72× 10²

Another example:

6324.4 in scientific notation will be written as = 6.3244 × 10³

Answer : The number of moles of precipitate, [tex]PbBr_2[/tex] formed will be 0.01 moles.

Explanation : Given,

Concentration of NaBr = 0.200 M

Volume of solution = 100.0 mL = 0.1 L      (1 L = 1000 mL)

First we have to calculate the moles of NaBr.

[tex]\text{Moles of NaBr}=\text{Concentration of NaBr}\times \text{Volume of solution in L}[/tex]

[tex]\text{Moles of NaBr}=0.200M\times 0.1L=0.02mol[/tex]

Now we have to calculate the moles of precipitate, [tex]PbBr_2[/tex] formed.

The balanced chemical reaction is:

[tex]2NaBr(aq)+Pb(NO_3)_2(aq)\rightarrow PbBr_2(s)+2NaNO_3(aq)[/tex]

From the balanced chemical reaction we conclude that:

As, 2 moles of NaBr react to give 1 mole of [tex]PbBr_2[/tex]

So, 0.02 moles of NaBr react to give [tex]\frac{0.02}{2}=0.01[/tex] mole of [tex]PbBr_2[/tex]

Therefore, the number of moles of precipitate, [tex]PbBr_2[/tex] formed will be 0.01 moles.

The number of mole of the precipitate (i.e PbBr₂) formed when 100 mL of 0.2 M NaBr react with excess Pb(NO₃)₂ is 0.01 mole

Volume = 100 mL = 100 / 1000 = 0.1 L

Molarity of NaBr = 0.2 M

Mole = Molarity x Volume

Mole of NaBr = 0.2 × 0.1

2NaBr(aq) + Pb(NO₃)₂(aq) → PbBr₂(s) + 2NaNO₃ (aq)

From the balanced equation above,

2 moles of NaBr reacted to produce 1 mole of PbBr₂.

Therefore,

0.02 mole of NaBr will react to produce = [tex]\frac{0.02}{2} \\\\[/tex] = 0.01 mole of PbBr₂.

Thus, the number of mole of the precipitate (i.e PbBr₂) produced from the reaction is 0.01 mole

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Answer:

= .7567105263

Explanation:

1 atm = 760 mmHg

575.1 mmHg (1 atm/760mmHg) = .7567105263 atm

Answer:

The correct option is C

Explanation:

Chemical equilibrium is a state in which there is no net change in the amount of reactant and products formed over time. This reaction is a reversible reaction, hence the reaction can keep proceeding in either direction until the products formed are equal in mass to that of the reactants or the products been reversed back to the reactants until both sides (product and reactant) achieve equal mass.

Answer:

The correct answer is b.

Explanation:

hope this helps u

Answer:

Bryna is correct it is B

Explanation:

Answer:

Above 7

Explanation:

The equivalence point of any titration can be read off from the appropriate titration curve.

A titration curve is a plot of the pH of analyte against the volume of titrant added.

For a strong base and weak acid, the equivalence point lies above 7.

The pH of the resulting salt to be pH> 7 .

The equivalence point of any titration can be read off from the appropriate titration curve. A titration curve is a plot of the pH of analyte against the volume of titrant added. It is a point in titration at which the amount of titrant added is just enough to completely neutralize the analyte solution. At the equivalence point in an acid-base titration.

For a strong base and weak acid, the equivalence point lies above 7.

Find more information about Equivalence point here:

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