What is the variable in an experiment?
A the glass tubes you use
B the questions you ask
C the thing you want to test
D the part that stays the same

A gas mixture containing oxygen, nitrogen, and He has a total pressure of 189.9 kPa. If PO2 = 104.6 kPa and PN2 = 13.0 kPa, PHe is 72.3 kPa.

Static pressure and velocity pressure are added to create total pressure. There is static pressure in a fluid that is not flowing. The pressure required to accelerate air from a zero velocity to a specific velocity that is proportional to the kinetic energy of the air stream is known as velocity pressure.

Consider the friction that exists between a fluid and the interior surface of a pipe. The fluid's density and velocity are used to compute the dynamic pressure: the total pressure in a mixture of ideal gases is the total of the partial pressures of the individual gases.

Total pressure = PO2  + PN2 + PHe

189.9 kPa = 104.6 kPa + 13.0 kPa + PHe

PHe = 72.3 kPa

Thus, A gas mixture containing oxygen, nitrogen, and He has a total pressure of 189.9 kPa. If PO2 = 104.6 kPa and PN2 = 13.0 kPa,PHe is  72.3 kPa.

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The value of the ΔH for the reaction is obtained as 1278 kJ .

We have to note that the enthalpy change of the reaction has to do with the heat that ahs been evolved or absorbed in a reaction. In this case we have to obtain the enthalpy change by looking at the combustion reaction that has been shown here.

It is clear that from the thermochemical reaction equation, there is the evolution of about 1278 kJ of heat in the process of the reaction as shown in the question that we have above.

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The electrons in the 2p sub level have the smallest binding energies, which is the best explanation for how the spectrum is consistent with the electron shell model of the atom. Option D is correct as a result.

Photoemission spectroscopy, often referred to as photoelectron spectroscopy, measures the amount of energy emitted by electrons from solids, gases, or liquids via the photoelectric effect. This procedure involves getting the energy for the electrons from an outside source, such as sunlight.

The photoelectric effect is a process in which electrons receive energy from an external source, such as sunlight, become excited, and transition from the ground state to the excited state. As a result of this process, there is a constant flow of electrons, which in turn causes a flow of energy.

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According to the data collected during the experimental reaction in the laboratory, and the balanced equation of the reaction, 5 moles of iron (Fe) and 2.5 moles of aluminum oxide (Fe2O3) were produced.

Fe2O3 + 2Al → 2Fe + Al2O3

If 1 mole of Fe2O3 is combined with 2 moles of Al

So 3 moles of Fe2O3 combine with x moles of Al

X moles of Al = 3 moles Fe2O3 x 2 moles Al / 1 mole Fe2O3 = 6 moles

Limiting reagent: Al, because there are only 5 moles available

If 2 moles of Al produce 2 moles of Fe

So 5 moles of Al produce x moles of Fe

X moles of Fe = 5 moles of Al x 2 moles of Fe / 2 moles of Al = 5 moles

If 2 moles of Al produce 1 mole of Fe2O3

So 5 moles of Al produce x moles of Fe2O3

X moles of Fe = 5 moles of Al x 1 mole of Fe2O3 / 2 moles of Al = 2.5 moles

By establishing the balanced equation of the reaction and the stoichiometric relationships, the amount of limit reagent is first determined and with this data, the moles of products are later determined.

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The argument that supports the claim that dissolving solid calcium chloride (CaCl2) in water is a chemical change is A. The ionic bond among calcium and chloride ions has been broken..

When solid calcium chloride is added to water, the ionic bonds between the calcium ions (Ca2+) and chloride ions (Cl-) are broken apart by the polar water molecules. The calcium ions and chloride ions are then surrounded by the water molecules, forming a new chemical compound called calcium chloride hydrate (CaCl2*xH2O) which is different from the original solid calcium chloride. This process is a chemical change because it creates new substances and the original chemical bonds are broken and new bonds are formed.

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the complete question is:

Which of the following arguments supports the claim that dissolving calcium chloride (CaCl2) in water results in a chemical change?

A. The ionic bond among calcium and chloride ions has been broken.

B. By evaporating the water, the solid calcium chloride can be recovered.

C. The ions found in the solid remain in the solution and have not changed.

D. Ions are attracted by the polar water molecules.

The element with electronic configuration 2s1, which is lithium, has a violent reaction with cold water.

The most reactive metals in the periodic table are the alkali metals (Li, Na, K, Rb, Cs, and Fr); they all react with cold water violently or even explosively, displacing hydrogen. In the reduction of water to hydrogen gas (H2) and the metal ion hydroxide (OH), Group 1 Metal (M) is oxidised to its metal ions.

The second most reactive metals in the periodic table are the alkaline earth metals (Be, Mg, Ca, Sr, Ba, and Ra), which also exhibit increased reactivity in higher periods like the Group 1 metals. The only alkaline earth metal that does not react with water or steam, even when heated to a high temperature, is beryllium (Be).  Furthermore, beryllium has an exterior oxide layer that is robust, which reduces its reactivity at lower temperatures.

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The final temperature of the mixture is 218.1°C.

The Specific Heat of gold 0.0123 J.

Specific heat is known to be the amount of energy required to raise the temperature of a unit mass of a substance by 1 degree. It is a physical property of matter, usually expressed in units of Joules/Kilograms/Kelvin (J/kgK).

Mass of gold = 325 g

Heat absorbed by water = mass of gold x specific heat x temperature change

325 x 0.128 x 405

Heat absorbed by water = 154,400 J

Heat capacity of water = mass of water x specific heat

200 x 4.184

Heat capacity of water = 836.8 J/degree Celsius

Final temperature = (heat absorbed by water ÷ heat capacity of water) + Initial temperature

Final temperature = (154400 ÷ 836.8) + 22

Final temperature = 218.1°C

Q = mcΔT

836.8 J/°C = 325 × c × (427°C - 218.1°C)

836.8 J/°C = 325 × c × 208.9

c = 836.8/(325 × 208.9)

c = 836.8/67,892.5

c = 0.0123 J

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Water is called a ‘universal solvent' because water can dissolve much more substances than any other liquid found in nature but water cannot dissolve every substance.

Water is referred to as a "universal solvent" because it has a considerably wider range of natural solvent properties than any other liquid. However, water is not capable of dissolving all compounds.

For instance, water cannot dissolve hydroxides, fats, or waxes because oppositely charged particles are not very soluble in water. Hydrogen and oxygen atoms are arranged polarly in water molecules.

The oxygen atom has a negative charge, while the hydrogen atom on one side has a positive charge.The water molecule can more easily attach to various compounds thanks to these charges.

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Because it can dissolve a greater variety of chemicals than any other natural liquid, water is referred to as a "universal solvent," though it does not dissolve all substances. The option  C is true.

In comparison to other liquids, water has a much larger spectrum of natural solvent qualities, earning it the moniker "universal solvent". Nevertheless, not all substances can be dissolved by water.

Because water is not highly soluble in oppositely charged particles, it cannot dissolve hydroxides, fats, or waxes, for example. Water molecules have polar arrangements of the hydrogen and oxygen atoms.

In contrast to the hydrogen atom on one side, which has a positive charge, the oxygen atom has a negative charge.

These charges allow the water molecule to more readily bind to different substances.

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The reactivity of metals depends upon their position in the periodic table and their nature of undergoing chemical reactions.

The primary difference between metals is the ease with which they undergo chemical reactions. The elements toward the bottom left corner of the periodic table are the metals that are the most active in the sense of being the most reactive. Such as alkali metals like Lithium, sodium, and potassium all react with water, thus they are reactive in nature than the metals belonging to alkaline earth metals. The nature of more reactivity of alkali metals is due to larger atomic radius and low ionization energies and they have only one valence electron in its outermost shell.

Thus, the reactivity of metals depends upon their position in the periodic table and their nature of undergoing chemical reactions.

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1. Kidney receive the waste product carried by the blood.

2. Homeostasis is the ability to maintain a relatively stable internal state that persist despite changes in the world outside.

3. The respiratory system and circulatory system work together by exchanging of oxygen and carbon dioxide.

4. Oxygen is a gas that the body needs.

5. Chemical signals are carried out by circulatory system that control the speed of digestion.

6. Oxyhemoglobin is a combination of hemoglobin and oxygen that enters in the body.

7. The respiratory system and digestive system work as it absorbed oxygen that being distributed through the body.

8. The respiratory system is responsible for exchange of gases.

9. The circulatory system carries nutrients to the entire body cells.

10. The digestive system is responsible for food digestion.

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The surface temperature of a block of solid carbon dioxide (dry ice) is -78.5 degrees Celsius (-109.8 degrees F). Once it reaches this temperature, carbon dioxide completely bypasses the liquid state and transforms into a gas. One pound of dry ice produces 250 liters of carbon dioxide gas!

Carbon dioxide in the form of dry ice is employed. Sublimation is the process by which CO2 transforms from a solid to a gas without first undergoing a liquid phase, and it takes place at pressures lower than 5.13 atm and temperatures higher than 56.4 °C (216.8 K; 69.5 °F) (the triple point).

When a substance changes immediately from a solid to a gas without melting beforehand. The carbon dioxide is still present; it simply passes.

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Answer:

Sublimation

Explanation:

C

answer :

this is the structure if you want it

Using the Ideal Gas Law equation: [tex]PV=nRT[/tex]

STP also known as Standard Temperature  and Pressure is a set of conditions at sea level

At STP:

P = 101.3 kPa

T = [tex]0^o C[/tex] or 273 K

[tex]n=\frac{PV}{RT}[/tex]

[tex]n=\frac{101.3kPa)(3.7L)}{(8.31\frac{kPaL}{molK})(273K)}[/tex]

[tex]n = 0.16 mol[/tex]

There is 2.43 mg of ascorbic acid in the 5.00-mL sample, or 48.6 mg/100 mL of orange juice.

Explanation:

For i2+na2s2o3 titration,

I2 + 2 S2O3^-2 <--> 2 I^-1 + S4O6^-2

13.82 mL of 0.07203 M Na2S2O3 was needed to reach the starch indicator end point.

Number of moles of Na2S2O3 = 13.82*0.07203= 0.9954546 millimoles.

So, number of moles of excess I2 = 0.9954546/2 = 0.4977273 millimoles.

For oxidizing the ascorbic acid to dehydroascorbic acid

C6H8O6 + I2 --> C6H6O6 + 2 H+ + 2 I-

SO 1mole of I2 read for 1 mole of C6H8O6.

Initial I2 used = 50*0.01023 = 0.5115 millimoles.

Number of moles of I2 used = 0.5115 - 0.4977273 = 0.0137727 millimoles.

Number of moles of C6H8O6 in5 ml of orange juice = 0.0137727 millimoles.

Weight of C6H8O6 in5 ml of orange juice = number of moles * molecular weight = 0.0137727 * 176 = 2.4239952 mg

In 100 ml of orange juice = 2.4239952/5) *100 = 48.479904 milligrams per 100 mL. is the answer.

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The relationship between the enthalpy (ΔH) and entropy (ΔS) of a reaction that is never spontaneous is -ΔH, +ΔS option - B is correct answer.

When a reaction occurs spontaneously, the system doesn't require any additional energy input because the change in free energy is negative.

When the enthalpy change is negative and the entropy change is positive, the reaction is always spontaneous.

The free energy change is always positive and the reaction is never spontaneous if the reaction is endothermic (H positive) and the entropy change S is negative (less disorder).

Although a spontaneous reaction may result in an increase or decrease in entropy or enthalpy, it will always result in a decrease in free energy, which is a negative G.

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Answer:

152.12

Explanation:

hope it helps

Kong Mali po sorry

Cool in cold or lukewarm water for 20 minutes.

This should be done as soon as possible after an injury. Never use ice, ice water, cream, or greasy substances like butter on the burn. Be careful to keep the airways open when treating burn victims. Associated smoke inhalation injuries are very common, especially when the patient is burned in an enclosed space such as a room or building. Even people who have been burned outdoors can inhale smoke. Stop the burning process as soon as possible. Remove all clothing and jewelry near the burned area.

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The half-life of a radioactive isotope is the time it takes for half of the original number of atoms in a sample to decay.

The isotope with the shortest half-life among the given options is:

D) carbon-14

The half-life of carbon-14 is 5,730 years which is shorter than the other isotopes. Uranium-238 has a half-life of 4.5 billion years, potassium-40 has a half-life of 1.25 billion years and rubidium-87 has a half-life of 49.8 billion years, all are greater than the half-life of carbon-14.

So, carbon-14 is the isotope with the shortest half-life among the given options.

It is important to note that the half-life of an isotope is a constant property of the isotope. For example, the half-life of carbon-14 is always 5,730 years and does not change with the amount of carbon-14 present or any other factors.

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The size of an ion is determined by its atomic radius, which is a measure of the size of the atom from which the ion is formed. The atomic radius of an atom is generally determined by the size of its electron cloud. The size of the electron cloud is influenced by the number of electrons and the energy levels they occupy.

Of the ions given, Li+ has the smallest atomic radius because it has the smallest number of electrons and the highest effective nuclear charge, which means that its electrons are held more closely to the nucleus. Na+, K+, and CS+ have larger atomic radii than Li+ because they have more electrons and lower effective nuclear charges, which means that their electrons are held more weakly by the nucleus.

Therefore, the answer is CS+ has the largest radius.

Reactions that are reversible have the ability to move both forward and backward. Reactants change into products in a reversible reaction, but products can also change back into reactants.

In actuality, the opposing reaction as well as the forward reaction will occur simultaneously. In some chemical reactions, the reaction's products might combine to form the reactants' original form. Reversible reactions are what they are referred to as. To illustrate them, use the formula: A + B C + D. Only in one direction can irreversible chemical reactions take place. Reactants can transform into products, while products cannot transform back into reactants. Chemical reactions that can be reversed can happen both ways. The products can change back into the reactants, and the reactants can change back into the products.

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To solve this we must be knowing each and every concept related to ecosystem. Therefore, the maximum number of species that a system can safely support determines the carrying capacity in an ecosystem.

An ecosystem is the fundamental fundamental unit of such an environment where living and nonliving creatures interact with one another, both of which are essential for the continuation of life on Earth.

The maximum number of species that a system can safely support is known as carrying capacity. The ability of an ecosystem to replenish the food, water, environment, or other essentials that populations have to thrive are just a few examples of the numerous variables that may affect an ecosystem's carrying capacity of a specific species.

Therefore, the maximum number of species that a system can safely support determines the carrying capacity in an ecosystem.

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Chemical Indicator refers to a substance that changes color when there is a certain concentration of hydrogen ions in a solution.

Chemical indicators are any substances that provide a clear indication—typically a change in color—of the presence or absence of a certain chemical species, like an acid or an alkali, in a solution. One such chemical is methyl yellow, which gives an alkaline solution a yellow color. When introduced to acidic or alkaline solutions, substances are considered indicators when their color changes. There are several indicators that are frequently used in laboratories, including litmus, phenolphthalein, and methyl orange. Litmus paper: It turns red in acidic solutions and blue in basic ones. Methyl orange: This chemical exhibits a red color in an acidic solution and a yellow color in a basic solution.

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The energy that is released for the breaking of bonds is 229 kJ/mol.

We should be able to recall that the enthalpy of the reaction taken to be the energy that is evolved or absorbed in the reaction that is ongoing. We have to note that in the course of the reaction there would be the breaking and the making of bonds.

Now we know that;

The bond energy can be given as;

Sum energy of the broken bonds of reactants  - Sum of the energy of the formed bonds

Hence;

(945 + 498) - 2(607)

1443 - 1214

= 229 kJ/mol

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The standard form of scientific notation for 0. 010x 10e5 is 1.0 × 10^3.

Scientific notation is a form of presenting large numbers or very small numbers in a simpler form.

There are some rules to write scientific notation:

The base should be always 10. The exponent must be a non-zero integer.

Absolute value of the coefficient should be greater than or equal to 1 but it should be less than 10.The mantissa carries the rest of the significant digits of the number.

The power of 10 will be positive, if the given number is multiples of 10 then the decimal point has to move to the left. The power of 10 will be negative If the given number is smaller than 1 and then the decimal point has to move to the right.

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Yes, calcium oxide (CaO) reacts with carbon monoxide (CO) to form calcium carbonate (CaCO3) and oxygen gas (O2). The reaction can be represented by the following equation:

CaO + CO -> CaCO3 + O2

This reaction is an example of a chemical change, as it results in the formation of a new substance with different chemical properties. The reaction is also exothermic, meaning that it releases heat.

Calcium oxide is a white solid that is used in a variety of applications, including cement production and the purification of flue gases. Carbon monoxide is a colorless, odorless gas that is toxic to humans when inhaled. It is produced as a byproduct of the incomplete combustion of fossil fuels.

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Physical properties  such as  mass, weights , density can be common for one or more substances hence cannot be used for identification while magnetism is unique for each substance ,hence used for identification.

Any property which describes the state of a physical system is called as a physical property.Changes in physical properties are used to describe changes between the states. They are often related to as observable properties.

Physical property which can be quantified is a physical quantity. These are also classified further with respect to their directionality. Physical properties are differentiated from chemical properties by the way they determine how a substance behaves in a chemical reaction.

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