Why is the average atomic mass used when calculating grams of a
substance?
A. The average atomic mass is known to more significant figures.
B. The elements in the substance are mixtures of their isotopes.
C. The exact weights of the isotopes are not known.
D. The number of isotopes in the sample is constantly changing.

The answer is zero also I suggest googling the questions there is a quizlet with the answers

Answer:

1.Physical change

2. Chemical change

3. Heat

4.photosynthesis

5. composition

Answer:

Pottasium

Explanation:

because it is the nineteenth element

Answer:

The answer is B. Potassium.

Explanation: Potassium has 19 electrons that are organized like the image if you count the electrons on each obital. This answer is correct on edge 2020. Hope this helps!

de Broglie's wave equation describes that particles have wave properties. The equation is  

   λ = h/mv

Where λ  is the wave length of the particle (m), h is the Planck's constant (6.62607 x 10⁻³⁴J s), m is the mass of a particle (kg) and v is the velocity (m/s).

λ = ?

h =  6.62607 x 10⁻³⁴ J s

m =200 g = 0.2 kg

v = 20 m/s

By substitution,

   λ  = 6.62607 x 10⁻³⁴ J s / (0.2 kg x 20 m/s)

   λ  = 1.66 x 10⁻³⁴ m

Hence, the wavelength of the 200 g ball 1.66 x 10⁻³⁴ m.

Answer:

B. Ester

Explanation:

"Esters have the general formula RCOOR′, where R may be a hydrogen atom, an alkyl group, or an aryl group, and R′ may be an alkyl group or an aryl group but not a hydrogen atom."

The type of molecule is ester.

A molecule is a collection of  more than one atom bound together by chemical bonds; based on the circumstances, the phrase will not include ions that meet this requirement.

Esters were chemical molecules formed by mixing an oxoacid and a hydroxyl substance like alcohol as well as phenol.

It can be seen that molecule have -COO group which represent ester group. Hence, given molecule have ester group.

Therefore, the correct answer will be option (B).

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Answer:

0.68

Explanation:

This is because the formula for finding density is mass/volume. Therefore the equation becomes 5.6/8.2 giving you 0.68

Answer:

see explanations

Explanation:

4NH₃(g) + 5O₂(g) => 4NO(g) + 6H₂O(g)

Ci(NH₃) = 3.5mole/4L = 0.875M

Cf(NH₃) = 1.6mole/4L = 0.400M

Rate-1 => Δ[NH₃]/Δt = |(0.400M - 0.875M)/3min| = 0.158M/s

Rate-2 => 6(Δ[NH₃]/Δt) =  4(Δ[H₂O]/Δt) => 6/4(0.158M/s) = 0.237M/s

Rate-3 => 5(Δ[NH₃]/Δt) =  4(Δ[O₂]/Δt) => 5/4(0.158M/s) = 0.237M/s

_________________________________________________________

NOTE: When setting up comparative rate expressions for a given reaction, set the rates expressions as equal then swap coefficient values.  Then solve for rate of interest and substitute givens.      

example: for NH₃ and H₂O

              4NH₃(g) + 5O₂(g) => 4NO(g) + 6H₂O(g)

              =>  6(Δ[NH₃]/Δt) =  4(Δ[H₂O]/Δt)

              =>  Δ[H₂O]/Δt = 6/4(Δ[NH₃]/Δt) = 6/4(0.237M/s) = 0.237M/s

Answer: Scientists are working on nuclear fusion process. Nuclear fusion is the process in which two atomic nuclei combine to form another nuclei. In the process either energy is absorbed or released due to the difference in the mass of reactants and products.

Explanation:

Answer:

Mass of each weight = 56.7 gram per piece

Explanation:

Given:

Lead’s density = 11.34 g/mL

Number of weights = 50

Volume of box = 250 mL

Find:

Mass of each weight

Computation:

Mass = volume x density

Mass = 250 x 11.34

Mass = 2,835 gram

Mass of each weight = Total Mass / Number of weights

Mass of each weight = 2,835 / 50

Mass of each weight = 56.7 gram per piece

[tex]okay \: bro[/tex]

Answer is [tex]32[/tex]

Explanation:

There are mainly four shells in an atom namely K, L, M, and N.

By using 2n², we can find the maximum number of electrons present in M shell.

Let, K = 1st shell, L = 2nd shell, M = 3rd shell, and N = 4th shell.

K = 1, L = 2, M = 3 and N = 4.

K = 2n² = 2(1)² = 2(1) = 2.

L = 2n² = 2(2)² = 2(4) = 8.

M = 2n² = 2(3)² = 2(9) = 18.

N = 2n² = 2(4)² = 2(16) = 32.

So, The maximum number of electrons present in the M shell is [tex]32.[/tex]

Answer:

[tex]\boxed {\boxed {\sf 8.38 \ L}}[/tex]

Explanation:

We are asked to find the new volume of a gas after a change in temperature. We will use Charles's Law, which states the volume of a gas is directly proportional to the temperature. The formula for this law is:

[tex]\frac {V_1}{T_1}= \frac{V_2}{T_2}[/tex]

The gas starts at 100 degrees Celsius and a volume of 33.5 liters. Substitute these values into the formula.

[tex]\frac {33.5 \ L}{100 \textdegree C}=\frac{ V_2}{T_2}[/tex]

The gas is cooled to 25 degrees Celsius, but the volume is unknown.

[tex]\frac {33.5 \ L}{100 \textdegree C}=\frac{ V_2}{25 \textdegree C}[/tex]

We want to find the volume of the gas after it is cooled.  We must isolate the variable V₂. It is being divided by 25 degrees Celsius and the inverse of division is multiplication. Multiply both sides of the equation by 25 °C.

[tex]25 \textdegree C*\frac {33.5 \ L}{100 \textdegree C}=\frac{ V_2}{25 \textdegree C}* 25 \textdegree C[/tex]

[tex]25 \textdegree C*\frac {33.5 \ L}{100 \textdegree C}= V_2[/tex]

The units of degrees Celsius cancel.

[tex]25*\frac {33.5 \ L}{100 }= V_2[/tex]

[tex]8.375 \ L = V_2[/tex]

The original measurements have 3 significant figures, so our answer must have the same. For the number we found, that is the hundredth place. The 5 in the thousandths place tells us to round the 7 up to an 8.

[tex]8.38 \ L \approx V_2[/tex]

The new volume after the gas is cooled is approximately 8.38 liters.

Answer:

A). 2.1 × [tex]10^{-2}[/tex]

Explanation:

Given reaction,

2[tex]HF[/tex] (g) ⇄ [tex]H_{2}[/tex] (g) + [tex]F_{2}[/tex] (g)

The concentrations are as following;

[tex]HF[/tex] = 5.82 × [tex]10^{-2}[/tex] M

[tex]H_{2}[/tex] = 8.4 × [tex]10^{-3}[/tex] M

[tex]F_{2}[/tex] = 8.4 × [tex]10^{-3}[/tex] M

So,

[tex]K_{eq}[/tex] = [([tex]H_{2}[/tex] ) × ([tex]F_{2}[/tex])] ÷ [[tex]HF[/tex]]^2

Now,

We can determine the value of [tex]K_{eq}[/tex] by substituting the values in above formula:

[tex]K_{eq}[/tex] = [ (8.4 × [tex]10^{-3}[/tex] M) × (8.4 × [tex]10^{-3}[/tex] M)] ÷ [(5.82 × [tex]10^{-2}[/tex])^2

= 2.08 * [tex]10^{-2}[/tex]

=  2.1 × [tex]10^{-2}[/tex]

∵ [tex]K_{eq}[/tex] = 2.1 × [tex]10^{-2}[/tex]

Thus, option A is the correct answer.

Explanation:

here's the answer to your question

Answer:

I'm not really sure. Sorry dude.

Explanation:

Sorry.

Answer:

E

Explanation:

kinetic energy of linear motion

[tex]k.e = \frac{1}{2} m {v}^{2} [/tex]

kinetic energy, K.e= 100joules

mass, m = 2kg

velocity, v =?

substituting the values into the formula :

[tex]100joules = \frac{1}{2} \times 2kg \times {v}^{2} [/tex]

[tex] {v }^{2} = 100[/tex]

[tex]v = \sqrt{100 } [/tex]

[tex]v = 10m { \sec }^{ - 1} [/tex]

Answer: 6 moles of [tex]KClO_3[/tex] will be decomposed.

Explanation:

We are given:

Moles of oxygen gas produced = 9 moles

The chemical equation for the decomposition of [tex]KClO_3[/tex] follows:

[tex]2KClO_3\rightarrow 2KCl+3O_2[/tex]

By the stoichiometry of the reaction:

If 3 moles of oxygen gas is produced by 2 moles of [tex]KClO_3[/tex]

So, 9 moles of oxygen gas will be produced by = [tex]\frac{2}{3}\times 9=6mol[/tex] of [tex]KClO_3[/tex]

Hence, 6 moles of [tex]KClO_3[/tex] will be decomposed.

Explanation:

There are certain metals that are less reactive compared to standard hydrogen electrode.

So, such metals do not release hydrogen gas in a reaction with dilute acids.

Examples of such metals are:

copper,silver,gold,platinum,mercury.

Answer:

A burning match stick is brought

near the mouth of the test tube, but no sound is

heard. That means hydrogen gas is not released in this reaction and the metal may be a less reactive metal and it is one among the above list of metals.

Answer:

i think A.

Explanation:

bc B. makes the molecules hight temp = move faster = more collisions = higher rate, C. it's use is to make reactions rates increase, D. somthung abt more surface area and easier collisions

Explanation:

The given chemical equation is:

[tex]2A + 4B -> 2C + 2D[/tex]

The rate of the reaction is 0.0352 M/s.

During the course of the reaction, the rate of reactants decreases, and the rate of products increases.

The rate of disappearance of B is shown below:

[tex]rate=-\frac{1}{4} \frac{d[B]}{dt}[/tex]

So, rate of change of B is :

[tex]rate of change of B =- rate * 4\\=-0.0352 M/s * 4\\=-0.1408M/s\\\\=-0.141M/s[/tex]

Option C.

In the given reaction, rate of change of reactant B is equal to -0.141 M/s.

Rate of any chemical reaction defines the speed of the completion of that reaction.

In the question given reaction is:

2A + 4B ----> 2C + 2D

Rate of reaction = 0.0352 M/s.

Rate of the reaction with respect to the reactant B is written as:

Rate = [tex]${\rm{ - }}\frac{{\rm{1}}}{{\rm{4}}}\frac{{\left[ {{\rm{dB}}} \right]}}{{{\rm{dT}}}}$[/tex], where negative sign shows the disappearance of reactant B.

Rate of change of B i.e. [tex]$\frac{{{\rm{dB}}}}{{{\rm{dT}}}}$[/tex] =  4 × (-rate)

[tex]$\frac{{{\rm{dB}}}}{{{\rm{dT}}}}$[/tex] =  4 × (-0.0352) = -0.1408 = -0.141 M/s

Hence, -0.141 M/s is the rate of change of B.

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Answer:

Triads were groups of 3 elements with similar chemical and physical properties. Beryllium, magnesium, and calcium are all earth alkalis found in the earth

Explanation:

Answer:

A water molecule consists of two atoms of hydrogen linked by covalent bonds to the same atom of oxygen. Atoms of oxygen are electronegative and attract the shared electrons in their covalent bonds.

Answer:

Gas

Explanation:

If you move a substance from one container to another and its volume changes, the substance is a gas. This is because, gases do not have fixed volume and shape; their shape and volume depend on the container used.

Answer:

I think gas.

Explanation:

Because gas doesn't have fixed shape and size.

Answer:

The law of reciprocal proportions states that if two elements react individually with a given weight of a third element, the ratio of the masses with which they combine with the third element are either the same or a simple multiple of the ratio of the masses with which they combine with each other

The compounds formed includes;

1) Nitric oxide, NO

Nitrogen = 46.66% × 30.01 = 14

Oxygen = 53.34% × 30.01 = 16

2) Water, H₂O

Hydrogen = 11.21% × 18.01528 = 2

Oxygen = 88.79% × 18.01528 ≈ 16

3) Ammonia, NH₃

Hydrogen = 17.78% × 17.031 ≈ 3

Nitrogen = 82.22% × 17.031 ≈ 14

The ratio of nitrogen to oxygen in nitric oxide = 14:16 = 7:8

The ratio of nitrogen to hydrogen in ammonia = 14:3

The ratio in which hydrogen and oxygen combine with nitrogen = 3/16

The ratio of hydrogen and oxygen combine with each other in water = 2/16

Therefore, the ratio with which hydrogen and oxygen combine with nitrogen, is (2/3) times the ratio with which they combine with each other, which verifies the law of reciprocal proportions

Explanation:

Answer:

could occur at any temperature.

Explanation:

The spontaneity of a reaction is what determines whether the reaction will occur or not. A spontaneous reaction occurs easily.

The spontaneity of a reaction is predicted by the sign of ∆G.

When ∆G is positive, the reaction is not spontaneous. When ∆G is negative, the reaction is spontaneous.

Note that;

∆G= ∆H - T∆S

Where;

∆H = Change in enthalpy

∆S = Change in entropy

T= temperature

If ∆H is unfavourable and ∆S is favourable, the reaction can proceed at all temperatures because ∆G will always be negative.

It should be noted that a process that is unfavorable as regards to enthalpy, but favorable with respect to entropy could occur at any temperature.

Enthalpy(∆H) serves as amount of internal energy that a compound has, entropy( ∆S)  on the other hand serves as intrinsic disorder within the system.

However, spontaneity of a reaction determines likely hood of occurrence of a reaction, when the process is spontaneous, it makes the reaction to occurs easily.

We can conclude that whenever enthalpy is unfavourable and entropy of a system is favourable, then the spontaneity will be negative and the reaction will occur at any temperature.

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Answer:

since there are no lone pairs on the central atom, this would be a trigonal planar molecule. It's polar because the shape of it does not cancel its polarity (you can think of it as not having a balanced electronegativity pull, since the nitrogen is pulling on one side, and the oxygens are pulling on the other. It would be nonpolar if the there were 3 Oxygens).

Sorry this take a little bit long. I was a little confused by the odd valence number

Answer:

69.420 b=99699969

Answer:

What atoms are present in carbon tetrachloride?

There is 1 carbon, and 4 chlorine atoms (or chloride ions if you want to get technical). Tetra means 4 in Greek.

hope that helps❤

Answer:

there are no calcium atoms of n carbon tetrachloride

Answer:

C

Explanation:

I hypothesis needs to be tested to know whether it is true or not. Here is the definition:

A supposition or proposed explanation made on the basis of *limited evidence as a started point for further investigation*

While picking up a buret, an unknown solution left by a previous solution drips onto your hand - Gloves

While pulling an empty beaker off the shelf at the beginning of lab, it slips out of your hand onto the floor - Closed-toe shoes

While checking on a stirring solution, the solution splashes up towards your face - Goggles

While transferring a solution from a flask to a beaker, the solution accidentally spills down the front of the lab bench - Lab coat

Explanation:

So, according to the question. the matches will be:

While picking up a buret, an unknown solution left by a previous solution drips onto your hand - Gloves

While pulling an empty beaker off the shelf at the beginning of lab, it slips out of your hand onto the floor - Closed-toe shoes

While checking on a stirring solution, the solution splashes up towards your face - Goggles

While transferring a solution from a flask to a beaker, the solution accidentally spills down the front of the lab bench - Lab coat

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Answer:

petroleum

Explanation:

usually found sedimentary rock.

definition: a liquid mixture of hydrocarbons that is present in certain rock strata and can be extracted and refined to produce fuels including gasoline, kerosene, and diesel oil, oil