If a scientist wanted to compare air quality throughout the united states but was unable to test the air in every city, the scientist could compare the air quality in a ______ or subset of cities.

Answer: 106.68 cm

Explanation:

1 inch=2.54 cm

42 inches * 2.54 cm/1 in=

42 * 2.54 = 106.68 cm

445.616 lb of CO2.

Equation for the reaction:

C8H18 + 25/2O2(g) --> 8CO2(g) + 9H2O(g)

Given:

The volume of gasoline = 25gallon

Converting gallon to ml,

25 gallon * 3.785 l/1 gallon * 1000 ml/1 l

= 94,625 ml

Density of the gasoline = 0.692 g/ml

Mass = density * volume

= 94,625 * 0.692

=  65480g

Molar mass of octane = (8*12) + (18*1)

= 114 g/mol.

Number of moles = mass/molar mass

= 65480/114

= 574.390 mol.

From the above equation, 1 mole of octane was completely burnt to give off 8 moles of CO2.

By stoichiometry,

Number of moles of CO2 = 574.390* 8

= 4595.122 mol of CO2.

Molar mass of CO2 = 12 + (2*16)

= 44 g/mol

Mass of CO2 = number of moles * molar mass

= 4595.122 * 44

=202,185.40 g

Converting g to pound,

= 202,185.40 g *1 kg/1000 g * 2.204 lb/1kg

= 445.616 lb of CO2.

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The independent variable, also known as manipulated, is the one that changes and causes an effect on the depenedent variable. The manipulated variable is temperature. Option D.

Independent variables are those modified or changed by the researcher to study how this change affects another variable (the dependent one) and hence the results.

It also receives the name of the manipulated variable because the researcher alters its value or state to analyze its effect. These variables are voluntarily manipulated by the researcher.

In the exposed example,

Goal: To determine the effect of temperature on reaction rates.

Independent (manipulated) variable: Temperature

Dependent variable: time it takes the tablet to dissolve.

Temperature is what affects the time in which the tablet dissolves. The researcher changes temperature levels to analyze how much the time changes.  

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Complete question,

A group of students conducts an experiment to determine the effect of temperature on reaction rates. They perform three separate trials in this experiment.

In the first trial, they drop an antacid tablet into a beaker of water at a temperature of 40 °C and record how long it takes the tablet to completely dissolve.

In the second and third trials, they use the same type and amount of antacid, but they change the temperature of the water to 25 °C for the second trial and 5 °C for the third trial.

The manipulated variable in this experiment is the

A. type of antacid used

B. amount of antacid used

C. time it takes for the reaction to occur

D. temperature at which the reaction occurs

The quantity of heat released in kJ when 15.7 g of benzene in the liquid phase at 50.0 °C is converted to solid benzene at 2.0 °C is 3.32 kJ.

The quantity of heat released is calculated using the formula below:

The following values apply to benzene:

Moles of benzene = 15.7/78/11 = 0.20 moles

Heat evolved from 50 °C to 5.4 °C = 15.7 * 1.8 * (50 - 5.4) = 1260.4 J = 1.26 kJ

Latent heat of fusion = 0.2 * 9.9 = 1.98 kJ

Heat evolved on cooling from 5.4 °C to 2.0 °C = 15.7 * 1.51 * (5.4 - 2.0) = 80.6  J = 0.08 kJ

quantity of heat released = 1.26 + 1.98 + 0.08 = 3.32 kJ

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[tex]P_{solvent}[/tex] = [tex]X_{solvent }[/tex] × [tex]P\textdegree _{solvent}[/tex] and

ΔP = [tex]X_{solute}[/tex] ×[tex]P\textdegree _{solvent}[/tex]  are the two options that correctly shows the relationships between solute concentration and solution vapor pressure.

Vapour pressure over a pure liquid as calculated using the Clausius-Claperyron equation. A solution is created when a solute is added to a pure liquid; the pure liquid that was the solute's original container is now the solvent.

Whether the solute is volatile or nonvolatile will determine how the solute affects the vapour pressure above the solution. The sole reason nonvolatile solutes lower the vapour pressure above the solution is because of the solvent molecules.

It is more difficult to combine volatile solutes that produce miscible solutions because each item has a vapour pressure, and the overall vapour pressure is the sum of all the partial vapour pressures.

A solvent plus a solute make up a typical solution. One of the most popular solvents is water, and you may see how various solutes behave in it. Non-volatile solutes, for instance, do not vaporise and release gas. Despite having a low vapour pressure, they typically have a high boiling point.

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20^250 unique sequence can be formed with different 250 amino acid long polypeptides.

Therefore, the correct option is a) 20^250

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If the value of heat, q, is positive when the temperature of a sample of water changes, then : the temperature of water was increased.

What is the relation between heat flux and temperature?

A substance's temperature is a macroscopic indicator of how quickly the atoms or molecules inside are vibrating about their mean locations. The increase in kinetic energy of these particles is reflected as an increase in temperature when heat is applied to a body.

The heat q and the temperature change Δ T : connection is the mathematical relationship at the core of this inquiry.

q = m c Δ T ,

where c is the substance's specific heat capacity and m is the substance's mass. The last two amounts can never be negative, it should be noted.

A positive value of heat hence always suggests a positive change in temperature. In other words, if heat is positive, the substance has received heat energy, increasing its ultimate temperature over its initial temperature.

Question:

If the value of heat, q, is positive when the temperature of a sample of water changes, then:

a. the temperature of water was decreased.

b. the temperature of water was increased.

c. it depends on whether mass and specific heat values are positive or negative.

d. None of the above.

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On its website, the epa claims that sulfur dioxide levels have fallen by 85 between 1990 and 2016.

What is SO2?

The national ambient air quality criteria for SO2 set by the EPA are intended to guard against exposure to all sulphur oxides (SOx). The most concerning component, SO2, serves as a marker for the larger group of gaseous sulphur oxides (SOx). At far lower quantities than SO2, the atmosphere contains other gaseous SOx (such SO3).

The largest source of SO2 in the atmosphere is the combustion of fossil fuels by power plants and other industrial facilities.

State and local governments will be able to comply with the EPA's national and regional rules to reduce emissions of SO2 and pollutants that create sulphur oxides (SOx) and assist them achieve the Agency's national air quality goals.

Now, So2 concentration in 1990 = 124 ppb

So2 concentration in 2016 = 16 ppb

Thus decrease in concentration of so2 is 108 ppb

Hence, decrease percentage = 87.09 % (ans)

Thus the claims are accurate.

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In this experiment, simple organic compounds as well as more sophisticated organic compounds including amino acids and hydrocarbons were created.

What is Stanley miller's experiment?

Stanley Miller, a scientist, carried out an experiment in 1953 that might shed light on what happened on the early Earth billions of years ago. In a flask containing a mixture of methane, ammonia, hydrogen, and water, he passed an electrical charge across it. Organic substances, such as amino acids, were produced as a result.

Based on the idea that life might have started from simple chemicals found on the early Earth, Miller conducted the renowned experiment in 1953.

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The new concentration of the solution of KBr diluted to 500 mL is 0.106 M

To solve this problem, the formula and the procedure that we have to use is:

c1 * v1 = c2 * v2

Where:

Information about the problem:

Applying the dissolution of concentrations formula and clearing the concentration of the diluted solution(c2), we get:

c1 * v1 = c2 * v2

0.530 M * 100.0 mL = c2 * 500.0 mL

c2 = (0.530 M * 100.0 mL ) / 500.0 mL

c2 = 0.106 M

In chemistry a solution is known as a homogeneous mixture of two or more components called:

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The reactants has greater energy in an exothermic reaction. Exothermic reactions often produce heat as defined by thermochemistry.

Exothermic reactions often produce heat as defined by thermochemistry as "reactions for which the total standard enthalpy change H is negative."

According to the energy diagram below, in an exothermic reaction, the reactants have a greater energy level than the products. The products are therefore more stable than the reactants. Overall, the reaction's H H H is negative, meaning that energy is expelled as heat.

When new bonds form in the products, less energy is produced during an exothermic reaction than is required to break bonds in the reactants. Energy is continuously released during an exothermic process, frequently in the form of heat. Exothermic reactions characterise all combustion processes.

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The correct answer is [a].The percent by mass of sodium chloride in a solution of 14.0 g of sodium chloride in enough water to make 91.0 g of solution is 15.4%.

Solution, in chemistry, homogenous mixture of two or more substances in relative amounts that can be varied continuously up to what is called the limit of solubility.

The term solution is commonly applied to liquid state of matter, but solutions of gases and solids are possible. Air, for example, is a solution consisting chiefly of oxygen and nitrogen with the trace amounts of several other gases, and brass is a solution composed of copper and zinc.

Solutions play a significant role in the processes of life. In blood plasma, oxygen from the lungs dissolves and chemically joins with hemoglobin in red blood cells before being delivered to the body's tissues. The byproducts of digestion are also transported to other bodily areas in solution. Many real-world situations can be solved by using liquids' capacity to dissolve other liquids or solids.

Chemists take advantage of differences in the solubility to separate and purify materials and to carry out chemical analysis. Most chemical reactions occur in solution and are influenced by solubilities of the reagents. Materials for chemical manufacturing equipment are selected to resist solvent action of their contents.

Percent by mass= [tex]\frac{weight of solute}{weight of solution}[/tex]*100= [tex]\frac{14}{91}*100= 15.4%[/tex][tex]%[/tex]%

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James Chadwick discovered the neutron, which was the last of the subatomic particles to be characterized.

James Chadwick bombarded alpha particles on the beryllium surface using radioactive decay o polonium as a source. He discovered penetrating particles with no charge. These particles were fast-moving with no positive or negative charge.

These radiations were made incident on paraffin wax. This experiment was very similar to Rutherford's experiment.

The mass of the neutron was almost equal to the mass of the proton but its penetrating power was higher than a proton. It can penetrate several inches of lead.

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the point in time when a solid transitions from a solid to a liquid at a fixed pressure, usually standard pressure. The temperature at which a substance transitions from a solid to a liquid state is known as its melting point (or, less frequently, liquefaction point). Pressure affects a substance's melting point, which is typically reported at a standard pressure such as 1 atmosphere or 100 kPa.

the temperature, at any given fixed pressure, at which a solid and its liquid are in equilibrium.

The temperature at which a substance melts when heated is known as its melting point.

the degree to which a solid becomes liquid. When compared to the freezing point,

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The balanced chemical reaction is: ca(oh)2(aq) + 2hcl(aq)-->2 h2o(l).

Redox is a sort of chemical reaction where the substrate's oxidation states change.

An rise in an object's oxidation state or the loss of electrons is referred to as oxidation.

Gaining electrons or lowering an atom's oxidation state are both considered to be reductions in the context of chemical reactions.

Redox reactions can be divided into two categories:

only one electron (typically) moves from the reducing agent to the oxidant during an electron transfer. Redox couples and electrode potentials are frequently used to describe this type of redox reaction.

Atomic transfer refers to the movement of an atom from one substrate to another. For instance, when iron rusts, iron atoms get more oxidized as they change into an oxide at the same time.

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Answer:

any particle that isn't a proton

Explanation:

After fermentation was finished, a stout's hydrometer revealed a specific gravity of 1.15.

Certain gravity, commonly referred to as relative gravity and a dimensionless number, is the ratio of a substance's density to that of water at a specific temperature (has no unit). Since water has its highest density in the SI system at 4°C, or 1000 kg/m3, this temperature is widely used as a reference point.

A measurement of a substance's relative density in relation to the density of water at room temperature is called specific gravity (S.G.). Engineers typically use 60 F instead of the standard used by physicists of 39.2 F (4 C).

Specific gravity = density of liquid/ density of water at 4°C

= mass of liquid/(volume*density of water)

Thus specific weight = mass = 1150 kg.

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The standard metric unit of time is seconds.

What is the metric system of units?

The most common method for determining height, distance, and other daily objects is the metric system of measurement. Let's use a container of milk as an example. To determine the amount of milk, we use liters, and to determine the height of the jar, we use meters (or centimeters). This is due to the fact that these metric units, often known as SI units, are widely used around the world (International System of Units). Let's get started by finding out more about the metric system.

The basic metric unit of time is seconds.

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Since half-life of carbon-14 is 5600 years, 1.5625mg of the element will be remaining after 33600 years.

The duration needed for a quantity of a substance to decrease to half of its initial value is known as the half-life. In nuclear physics, the phrase is frequently used to indicate how rapidly unstable atoms disintegrate radioactively or how prolonged stable atoms last. The duration it takes for half of an element in a radioisotope to decay is known as the half-life. The faster an atom decays and the shorter its half-life, the more unstable it is. Additionally, the phrase can be used more broadly to describe any kind of exponential decay.

Given:

Initial quantity of substance, [tex]N_0[/tex] = 100mg

Half-life of the substance, [tex]t_{1/2}[/tex] = 5600 years

Time elapsed, t = 33600 years

To find:

Quantity of substance remaining, [tex]N_t[/tex] = ?

Formula:

[tex]N_t = N_0 * (\frac{1}{2}) ^ (\frac{t}{t_\frac{1}{2} } )[/tex]

Calculations:

[tex]N_t = 100 * (\frac{1}{2}) ^ \frac{33600}{5600}[/tex]

[tex]N_t = 100 * (\frac{1}{2}) ^6[/tex]

[tex]N_t[/tex] = 100 x 0.015625

[tex]N_t[/tex] = 1.5625mg

Result:

Remaining carbon-14 after 33600 years is 1.5625mg.

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According to catastrophists the rate of geological change is slow incremental changes

The catastrophic idea holds that severe, abrupt events with potentially global reach have formed the Earth in substantial part.  Contrast this with uniformitarianism, sometimes known as gradualism, which postulates that all of the Earth's geological features were produced through slow, incremental processes like erosion. Uniformitarians believed that all geological processes, including erosion, were identical throughout history and that the present held the key to understanding the past. Since the initial disagreements, a broader and more comprehensive understanding of geologic events has emerged. The scientific community now acknowledges that there have been some catastrophic events in the past, but that these can be explained as extreme instances of natural processes that can take place.

What is geological change?

dynamic activities or events that take place on the surface of the Earth as a result of the impact of natural factors like wind, moving water, ice, and snow, temperature changes, freezing and thawing, chemical reactions, seismic shaking, and the application of gravity. When a force is greater than the earth's material can withstand, it deforms, moves, or undergoes chemical reactions.

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The absolute pressure (in pa) is 4.0Pa.

The mass of one molecule of air may be computed as

m =  Molecular weight / Avogadro’s number

m = 28.97 / 6.023×[tex]10^{23}[/tex]

m = 4.81×[tex]10^{-23}[/tex] g

Then the density of air containing [tex]10^{12}[/tex] molecules, in SI units,

ρ =  [tex]10^{12}[/tex] × 4.81×[tex]10^{-23}[/tex] = 4.81×[tex]10^{-5} kg/m^{3}[/tex]

Finally, from the perfect gas law, , at 20°C = 293 K, we obtain the pressure:

p = ρRT

P = 4.81×[tex]10^{-5} kg/m^{3}[/tex]×287×293

p = 4.0Pa

So, the absolute pressure (in pa) is 4.0Pa.

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The Avogadro's number is used to obtain the required results as;

1) 4.69 g

2) 4.26 g

3) 2.158 g

4) 381 g

5) 348.5 L

6)  1008 L

7) 3.6 L

8) 4.7 * 10^4 g

9) 112 L

The Avogadro’s number could be used to deduce the amount of substance. Let us recall that in the theory of Professor Avogadro, the mole is the number of elementary entities of a substance. In this case these elementary entities is a reference to the atoms, molecules and ions that could be found in the substance. With that in mind, we shall now carry out the calculations.

1)  6.02 * 10^23 atoms of helium has a mass of 4g

7.06 x 10^23  He atoms of He has a mass of 4.69 g

2) 6.02 * 10^23 atoms of Mg has a mass of 24 g

1.07 x 10^23 Mg atoms has a mass of 4.26 g

3) 6.02 * 10^23 molecules of O2 has a mass of 32 g/mol

4.06 x 10^22 molecules of O2 has a mass of 2.158 g

4) 6.02 * 10^23 molecules of CO has a mass of 28 g

8.19 x 10^24 molecules CO has a mass of 381 g

5) Number of moles = 2800g/180 g/mol = 15.56 moles

Given that 1 mole occupies 22.4 L

15.56 moles occupies 348.5 L

6) Given that 1 mole occupies 22.4 L

45 moles occupies 1008 L

7) Number of moles of Fe = 9.2 g/56 = 0.16 moles

Given that 1 mole occupies 22.4 L

0.16 moles occupies 3.6 L

8) 6.02 * 10^23 particles have a mass of 102 g

2.8 x 10^26 particles have a mass of 4.7 * 10^4 g

9) Given that 1 mole occupies 22.4 L

5 moles of the acid occupies 112 L

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less than 25 gallons of flammable or combustible liquids can be stored in a room outside of an approved storage cabinet.

less than 60 gallons of flammable or 120 gallons of combustible could be stored in any of the storage cabinet.

Avoid storing flammable liquids on high shelves or in direct sunlight. Store flammable liquids during a well ventilated area. Caution: Never use environmental rooms (also called cold/ warm rooms) to keep flammable, combustible, or other hazardous materials.

When not using flammable liquids should be placed in an appropriate flammable storage cabinet. Individual containers must be clearly marked to point their contents and the degree of flammability. In opinion 50 litres of flammable liquids can be kept in a room within corrective flammable storage cabinets.

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Am, In, Ta, As, Se, Rn, Hf, Am

Tantalum and hafnium are transition metals.

An inner transition element is americium.

Main group elements include radon, selenium, and indium.

Metalloids include arsenic.

What is transition metals?

The concise IUPAC definition is expanded by Cotton and Wilkinson by detailing which elements are included. They add scandium and yttrium from group 3, which have a partially full d sub-shell in the metallic state, along with the elements of groups 4 to 11.

They classify lanthanum and actinium as group 3 elements, while they are actually categorized as lanthanides and actinides, respectively.

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Answer: three significant figures

Explanation: All zeroes between two nonzero digits are significant, for example, 101 contains three significant figures.

[tex] \bf \implies \: 15.5 \: km[/tex]

We know that,

1 m = 1000 km

1 km = 1/1000 m

We have converted 15500 m to km

[tex] \mapsto \bf \frac{155 \cancel{0} \cancel{0}}{10 \cancel{0} \cancel{0}} = \frac{155}{10} = 15.5 \: km[/tex]

The nuclide thorium-230 undergoes alpha emission to give radium-226

Thorium-230 undergoes alpha decay, a form of nuclear decay in which an alpha particle is ejected from the nucleus, and as a result, produces alpha radiation. Because of the imbalance in the energy working to hold the nucleus together or drive the nucleus apart caused by unstable isotopes' neutron to proton ratio, these isotopes are unstable.

This thorium then changes into protactinium 234 and experiences beta-negative decay to yield uranium 234 as a byproduct. With a half-life of 245,000 years, this final isotope progressively decays into thorium 230, another unstable nucleus. Only the creation of a stable nucleus can end any such decay chain.

The nuclide whose radioactive decay product is a certain daughter nuclide is referred to as the parent nuclide (plural parent nuclides) in physics.

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Answer:

Born:  21 November, 1851, Baltimore, Maryland, United States

Died: 17 April , 1898, Baltimore, Maryland, United States

He is an American baseball player,  known as being one of the inventors of the spitball pitch, which was rediscovered or reintroduced to the major leagues after he died. He earned run average: 2.86

Explanation:

I hope this helps

Answer:

of course A

Explanation:

1.89*10³

1890

PH = 2.64

PH = - log [H+]

[H+] = 0.00229 M

HA = 0.0199 M

Dissociation equation

HA --> H+ + A-

Ka = [H+][A-]/[HA]

[H+] = [A-]

Ka = (0.00229^2)/0.0158

=3.31 x 10^-4M

What is monoprotic acids?

Any acid with only one hydrogen atom in its formula is called a monoprotic acid, while some acids with multiple hydrogen atoms may also fall under this category. In other words, while all monoprotic acids contain only one hydrogen, not all single-hydrogen acids are monoprotic.
Therefore,

Enough of a monoprotic acid is dissolved in water to produce a 0.0158 m solution. the ph of the resulting solution is 2.64. calculate the a for the acid.

pH = 2.64

pH = - log [H+]

[H+] = 0.00229 M

HA = 0.0199 M

Dissociation equation

HA --> H+ + A-

Ka = [H+][A-]/[HA]

[H+] = [A-]

Ka = (0.00229^2)/0.0158

=3.31 x 10^-4M

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