What is the mass of a 7.426-mole sample of sodium hydroxide (NaOH molar mass = 40.0 g/mol)?
Select one:
5.360 g
40.00 g
179.1g
297.0 g

Answer:

I would say there would be 5-10% in a city, and maybe 10-20% in the country. It mainly varies depending on how big the city is, how many people/districts there are, and the size of the country, which makes it hard to give a certain percent of shops, as there may be small businesses included as well or new shops being built.

Hope this helps! This was pretty confusing for me as well so i hope the answer is alright (×﹏×)

Answer:

Chemical formulas tell you how many atoms of each element are in a compound, and empirical formulas tell you the simplest or most reduced ratio of elements in a compound. If a compound's chemical formula cannot be reduced anymore, then the empirical formula is the same as the chemical formula.

please give me brainliest

Answer:

P total = 1.25 atm

neon = 0.68 atm

argon= 0.35 atm

helium= x

1.25=0.68+0.35+x

1.25-0.68-0.35=x

x=0.22 atm

The molarity of the HCl acid will be 0.001 M.

A neutralization reaction is when an acid and a base react to form water and a salt and involves the combination of H⁺ ions and OH⁻ ions to generate water.

This is the neutralization of a strong acid (HCl) and a strong base (NaOH), which is ruled by this equation :

HCl (aq) + NaOH (aq) → NaCl (aq) + H₂O (l)

Mole Ratio : 1 mol HCl : 1 mol NaOH

Formula used ;

Molarity  = number of moles  / Volume  (in liters)

Solve for n ;

n = M × V

Substitute values and compute ;

n = 0.40 M × 0.025 liter = 0.01 moles NaOH.

As the molar ratio is NaOH : HCl

Therefore, there will be same number mole for the HCl

Now, Molarity of HCl Solution ;

Molarity = n / volume

Molarity = 0.01 / 10

             =  0.001 M HCl

Hence, The molarity of the HCl acid will be 0.001 M.

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The subshell that contains the valence electron for sodium is the s subshell

Valence electrons are the electrons located at the outermost shell of an atom

From the question, we are to determine the subshell that contains the valence electron(s) for sodium

The given electronic configuration for sodium is

1s²2s²2p⁶3s¹

The valence electron is the electron in the 3s orbital.

Hence, the subshell that contains the valence electron for sodium is s subshell

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Answer:

a.  P=188mmHg

Explanation:

A gas undergoing a change of volume and pressure at constant temperature (and not changing the number of molecules), follows Boyle's Law:  [tex]P_1V_1=P_2V_2[/tex]

The units of these quantities can be any measure of pressure and volume, so long as long as the units are the same between beginning and ending conditions.

Substitute and solve:

[tex]P_1V_1=P_2V_2[/tex]

[tex](685[mmHg])(131[mL])=P_2(478[mL])[/tex]

[tex]\dfrac{(685[mmHg])(131[mL\!\!\!\!\!\!\!\!\!{--}])}{478[mL\!\!\!\!\!\!\!\!\!{--}]}=\dfrac{P_2(478[mL]\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!{----})}{478[mL] \!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!{----}}[/tex]

[tex]187.730125523[mmHg]=P_2[/tex]

Accounting for significant figures, [tex]P_2=188[mmHg][/tex]

Answer: [tex]\text{CH}_{4}+2\text{O}_{2} \longrightarrow \text{CO}_{2}+2\text{H}_{2}\text{O}[/tex]

Explanation:

The unbalanced equation is

[tex]\text{CH}_{4}+\text{O}_{2} \longrightarrow \text{CO}_{2}+\text{H}_{2}\text{O}[/tex]

Balancing this equation, we get:

[tex]\boxed{\text{CH}_{4}+2\text{O}_{2} \longrightarrow \text{CO}_{2}+2\text{H}_{2}\text{O}}[/tex]

The statement that describes a question that can guide the design of a scientific investigation could be about the necessity of a controlled variable. The correct answer is A.

It is a variable whose values are controlled by the researcher during the course of experimental investigations.

When designing an experiment, it is necessary to identify the different variables that would be involved for a successful investigation.

Variables can be independent, dependent, controlled, or constant. Identifying the necessary variables will help in designing the experiment.

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Answer:

1.72 moles of H₂

Explanation:

The balanced equation

2Na+ 2H₂O → 2NaOH + 1C

tells us we'll get 1 mole of H₂ for every 2 moles of NaOH.  We can express this as a molar ratio:  (1 mole H₂)/(2 moles NaOH).

The reaction produces 138 g of NaOH.  Divide this mass by the molar mass of NaOH (39.99 g/mole)to obtain moles NaOH:

138g NaOH/(40 g/mole) = 3.45 moles of NaOH.

To find the moles H₂ produced, we can multiply the moles NaOH by the molar ratio from above:

(3.45 moles NaOH)*((1 mole H₂)/(2 moles NaOH) = (3.45/2) moles H₂.  [Note how the "moles NaOH" unit cancels, leaving just "moles H₂"]

We should produce 1.72 moles of H₂.

Answer:

CsCl

Explanation:

The ionic species are:

           Cs⁺   and Cl⁻

Answer:

It has protons, neutrons and electrons

the equation of the parabola is given as [tex]y = 1/4 (x-6)^2 +1[/tex]. D

Given the focus(6,2) and the directrix, y = 0

Use the formula

[tex]\sqrt{(x-6)^{2} + (y-2)^{2} } }[/tex] = (y - 0)

Find the square of both sides, square root is removed from the side with it and square added on the other side

[tex](x-6)^2 + (y-2)^2 = (y- 0)^{2}[/tex]

Expand the expression and bring all terms to one side

[tex]x^{2} - 6x - 6x + 36 +y^{2} -2y- 2y +4[/tex] = [tex]y^{2} - 0[/tex]

Collect like terms

[tex]x^{2} - 12x -4y + 40 = 0[/tex]

Make 'y' the subject of the formula

[tex]4y = x^{2} - 12x + 40[/tex]

Divide through by 4 and substrate 4 from 40 to give a perfect quadratic equation

[tex]y = 1/4( x^{2} - 12x + 36) + 4[/tex]

1/4 is dividing the quadratic equation [tex]x^2 - 12x +36[/tex]

Then divide factor by 4 to give 1, this is so because of the nature of the options given

[tex]y = 1/4( x^{2} -6x -6x +36) + 1[/tex]

Simplify the expanded quadratic equation

[tex]y = x (x -6) - 6 (x- 6)[/tex], we have [tex](x - 6) ^2[/tex]

Then insert in place into previous equation

[tex]y = 1/4 (x-6)^2 + 1[/tex]

Thus, the equation of the parabola is given as [tex]y = 1/4 (x-6)^2 +1[/tex]

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A food processing company might use titration to calculate the precise amount of salt in a particular food stuff.

A process of determining the concentration of a dissolved substance in terms of the smallest amount of reagent of known concentration required to bring about a given effect in reaction with a known volume of the test solution

The general source of error in titration has been;

A food processing company might use titration to calculate the precise amount of salt in a particular food stuff.

It can also be used to determine the concentration of vitamin C or vitamin E additives in foods.

Universal indicator can also work as the indicator in the lab.

When universal indicator is added to a solution, the color change can indicate the approximate pH of the solution.

Acids cause universal indicator solution to change from green toward red whereas, bases cause universal indicator to change from green toward purple.

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4. True

5. The amplitude of the ripples decreases as the circumference of the circle increases.

A wave is a disturbance that moves energy from one place to another.

Radio waves, gamma-rays, visible light, and all the other parts of the electromagnetic spectrum are electromagnetic radiation. Electromagnetic radiation can be described in terms of a stream of mass-less particles, called photons, each travelling in a wave-like pattern at the speed of light. Hence, the statement is true.

As the disturbance moves outwards the energy it carries is spread over a larger and larger region called the wavefront. For example, the ripples in the water lie in a circle with an ever-increasing circumference. The amplitude of the ripples decreases as the circumference of the circle increases.

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Gravity increases as the mass of either object increases.

Gravity is the force by which a planet or other body draws objects toward its centre. The force of gravity keeps all of the planets in orbit around the sun.

Since the gravitational force is directly proportional to the mass of both interacting objects, more massive objects will attract each other with a greater gravitational force. So as the mass of either object increases, the force of gravitational attraction between them also increases.

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Answer:

decane

Explanation:

decane has 10 carbon and 22hydrogen

The difference in an area with high concentration and an area with low concentration is called the concentration gradient.

A concentration gradient occurs when the concentration of particles is higher in one area than another.

In passive transport, particles will diffuse down a concentration gradient, from areas of higher concentration to areas of lower concentration, until they are evenly spaced.

This difference in an area with high concentration and an area with low concentration is called the concentration gradient.

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Answer:

See below

Explanation:

Tap water, bottled water and lake water are all examples of FRESH WATER and likely have the same specific gravity  ( or density) .

Ocean water is SALT WATER ....and depending on HOW MUCH salt is in the water, it can be quite a bit denser than fresh water ...which will allow the golf ball ( which is less dense)   to float .

Scientific theories are always testable. A theory may be changed as a result of new observations.

A scientific theory is a set of laws, facts and hypotheses that have a complete vision of an aspect of reality.

It is a proposed explanation for a set of observable phenomena.

It allows in this way to organize and understand the observations and to be able to predict or provoke other future observations.

Theories can be modified or improved as more information is collected.

That is, theories can continue to be tested indefinitely, and eventually rejected, if the tests lead to it.  

Therefore, a scientific theory is testable by using a research method.

As mentioned, any theory can be tested or rejected as more information is collected.

This information to prove or reject theories are interpretations of observable facts, which generates new statements or allows to accept those already included in the theory.

Then, a theory may be changed as a result of new observations.

Finally, scientific theories are always testable. A theory may be changed as a result of new observations.

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Answer:

testable & new observations

Explanation:

The two dark vertical lines in the spectrum shows that all wavelengths except those two cause an electron to move to a lower energy level. Hence, Option (D) is correct

A spectrum of electromagnetic radiation transmitted through a substance, showing dark lines or bands due to absorption at specific wavelengths.

The given fact is explained by the energy levels that electrons may be in are quantized, or vary by a specific amount.

When electrons go from one energy level to another, the difference in those energy level is a specific value, and not a range of values.

If they are transitioning upwards towards a higher energy, they will absorb the photons corresponding to the wavelength of light which has the specific amount of energy they need to ascend, resulting in dark lines.

Similarly, when the electrons transition from higher to lower energy, the same specific amount of energy is released and the emission spectrum shows lines in the places where the absorption spectrum was dark.

Hence, The two dark vertical lines in the spectrum shows that all wavelengths except those two cause an electron to move to a lower energy level. Therefore, Option (D) is correct

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Answer:

-1071 Joules

Explanation:

The Joule was introduced as the SI unit for energy in 1925.  One calorie is equal to approximately 4.184 joules(J).  This is a conversion factor that we can write two ways:

(1cal/4.184J) or (4.184J/1cal)

(265 cal)*(4.184J/1cal) = 1071 J

Since the energy is leaving the system, it should be written with a minus sign:  -1071J

Answer:

1,108.76 joules

Explanation:

There are 4.184 joules per calorie

4.184 x 265 = 1,108.76

Hydrometeorological hazards are caused by extreme meteorological and climate events, similar as cataracts, famines, hurricanes, tornadoes, or landslides.

Therefore these are the hydro-meteorological hazards.

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Answer:

1.1713 moles

Explanation:

RFM of N2O5=108

Moles of N2O5= mass/RFM= 63.25/108=0.5856 moles

Mole ratio of N2O5:NO2= 2:4

Therefore moles of NO2= 4/2*0.5856= 1.1713 moles

Answer:

I think its C

Explanation: cuz the pictures indicate that is returns to "normal" last.

The 18o-labeled methanol (CH3O*H) will appear in the products side at position b.

The 18O label will appear at position b in the product as indicated in the image.

This methoxy group in the product formed in position b comes from the 18O-labeled methanol (CH3OH).

While the oxygens at positions a and c in the product come from the unlabeled hemiacetal.

Thus, the 18o-labeled methanol (CH3O*H) will appear in the products side at position b.

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The relationship between temperature and water density is an inverse relationship.

A measure of the typical kinetic energy of the atoms or molecules in a system, the temperature is a physical variable that expresses hot and cold.

The definition of density is the mass of a substance per unit volume. Density is defined as the ratio of mass to volume, or mass per unit volume.

An inverse relationship exists between temperature and density. The density of water drops because of the increased distance between water molecules as temperature rises. Water's density rises when its temperature drops, but only to a certain extent.

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10 mol of H₂ required to produce 5 moles of methane (CH₄)  

Mole Ratio is a conversion factor between compounds in a chemical reaction, that is derived from the coefficients of the compounds in a balanced equation.

The mole ratio is therefore used to convert between quantities of compounds in a chemical reaction.

Given reaction ;

                                                  C + 2H₂ -------> CH₄  

from reaction                              2 mol           1 mol

from the question                      x mol           5 mol                       (given)

Now,

x = 2 x 15 / 1 = 10 mol

                     = 10 mol of H₂.

Hence, 10 mol of H₂ required to produce 5 moles of methane (CH₄)  

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