Why are black holes so difficult to detect?

Answer:

See explanation

Explanation:

The reaction equation is;

C3H8 (g) + 5O2(g) -------> 4H2O(g) + 3CO2(g)

From the formula;

Total enthalpy of reactants = (ΔHf of Reactant 1 x Coefficient) + (ΔHf of Reactant 2 x Coefficient)

Total enthalpy of products= (ΔHf of Product 1 x Coefficient) + (ΔHf of Product 2 x Coefficient)

Hence;

Total enthalpy of reactants =[(-103.85 * 1) + (0 * 5)] = -103.85 + 0 = -103.85 KJ/mol

Total enthalpy of products= [(-393.51 * 4) +(-241.82 * 3)] = (-1574.04) + (-483.64) = -2057.68 KJ/mol

Answer:

C₂H6

Explanation:

Among the given options, the formula A) C₂H6 represents a hydrocarbon (specifically, ethane). Option A

A hydrocarbon is a compound that consists of only carbon and hydrogen atoms. It is important to identify the formula that represents a hydrocarbon among the given options:

A) C₂H6: This formula represents ethane, which is a hydrocarbon. Ethane consists of two carbon atoms bonded together with single bonds and six hydrogen atoms.

B) C₂H5OH: This formula represents ethanol, which is not a hydrocarbon. Ethanol contains a hydroxyl group (-OH), indicating the presence of oxygen in addition to carbon and hydrogen atoms. It is an alcohol, not a hydrocarbon.

C) C₂H5Cl: This formula represents ethyl chloride, which is not a hydrocarbon. Ethyl chloride contains a chlorine atom (Cl) in addition to carbon and hydrogen atoms. It is a haloalkane, not a hydrocarbon.

D) C₂H6O: This formula represents ethanol, which, as mentioned before, is not a hydrocarbon. Ethanol contains an oxygen atom (O) in addition to carbon and hydrogen atoms. It is an alcohol, not a hydrocarbon.

Among the given options, the formula A) C₂H6 represents a hydrocarbon (specifically, ethane). It consists only of carbon and hydrogen atoms, making it a suitable representation of a hydrocarbon.

In summary, the formula C₂H6 (option A) represents a hydrocarbon, while the other options contain additional elements (oxygen or chlorine) that make them non-hydrocarbon compounds. Option A

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The best radioactive isotope for age-dating a rock from 50,000 years ago would be Carbon-14 (14C).

Carbon-14 (14C) is the most suitable radioactive isotope for dating materials up to approximately 50,000 years old, making it ideal for age-dating a rock from 50,000 years ago. This is because 14C is formed in the upper atmosphere when cosmic rays interact with nitrogen, and it is incorporated into living organisms through photosynthesis or consumption. After an organism dies, the 14C begins to decay at a known rate, known as the half-life, which is approximately 5730 years. By measuring the remaining amount of 14C in a sample, scientists can determine how long it has been since the organism died and, therefore, date the rock or material containing organic matter to estimate its age. Other radioactive isotopes with longer half-lives, such as Uranium-238 or Potassium-40, are better suited for dating much older rocks or minerals.

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The molarity of the aluminum sulfate solution is 0.144 M, the concentration of the aluminum cation is 0.144 M, and the concentration of the sulfate anion is 0.144 M.

Mass of aluminum sulfate (Al2(SO4)3) = 12.3 g

Volume of solution = 250 mL = 0.25 L

The molar mass of aluminum sulfate (Al2(SO4)3) is 342.15 g/mol.

For the calculation of molarity, we can use the formula:

Molarity = Number of moles of solute / Volume of solution in liters

We can find the number of moles of aluminum sulfate using the formula:

Number of moles = Mass / Molar mass

Thus, the number of moles of aluminum sulfate (Al2(SO4)3) is:

Number of moles = Mass / Molar mass= 12.3 g / 342.15 g/mol= 0.036 moles

Now, we can calculate the molarity of the solution:

Molarity = Number of moles of solute / Volume of solution in liters= 0.036 moles / 0.25 L= 0.144 M

The concentration of the aluminum cation and sulfate anion in the solution will be the same as the concentration of aluminum sulfate (Al2(SO4)3). Thus, the concentration of aluminum cation and sulfate anion will also be 0.144 M. Therefore, the molarity of the solution is 0.144 M, the concentration of the aluminum cation is 0.144 M and the concentration of the sulfate anion is also 0.144 M.

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Answer:

The answer is Gain 6 electrons.

Explanation: The reason for this is that for electrons to be stable, you need a valence shell of 8 electrons. Since it is arranged 2, 8, 2 , the outer shell is 6 less than 8 meaning it needs to gain 6 electrons.

Giant molecules are also referred to as macromolecules and polymers when numerous molecules are combined. These atoms are arranged in a three-dimensional structure and are joined by covalent bonds.

A giant molecule, also known as a macromolecule, is a usually large molecule crucial to biophysical processes, such as a protein or nucleic acid. It is made up of many atoms that are covalently bound. Large non-polymeric molecules including lipids and macrocycles, as well as biopolymers, are the most prevalent macromolecules in biochemistry. In addition to synthetic fibers, giant molecules can also be found in research materials like carbon nanotubes.

Different experts use different terminology for giant molecules. For instance, in biology, giant molecules refer to the four immense molecules that make up living things, while in chemistry, it refers to aggregates of two or more molecules that are held together by intermolecular forces rather than covalent bonds yet that is difficult to dissolve apart. The term giant molecule is frequently referred to as high polymer in British English.

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Answer:O B. Weak acid breaks down minerals by reacting with them.

Explanation:

Chemical weathering is the process whereby rain water which sometimes can be acidic ( As rain falls down it reacts with CO2 in the atmosphere and form acid rain), This  reacts  with the minerals contained in rocks, dissolves and degrades  them further to form entire  new minerals.

An example of a rock that is greatly affected by overexposure of  acid rain is  limestone containing calcite  which easily degrades by acid rain.

Other processes whereby Chemical weathering can occur are through reaction with water and oxygen.

Reactivity of non-metals depend on their ability to gain electrons. So, smaller is the size of a non-metal more readily it will attract electrons because then nucleus will be more closer to valence shell. ... Hence, Br is the non-metal which will be more reactive than At.

Answer:

br is more reactive than as

The process that changes the space between the grains in a metamorphic rock is recrystallization. What is Metamorphic rock? A metamorphic rock is a kind of rock that has undergone a transformation from its initial form due to extreme pressure, temperature, or other chemical processes.

The correct option is A.

Due to these processes, metamorphic rocks have different characteristics from their initial type, including texture, structure, mineralogy, and other characteristics. Features of Metamorphic Rocks: They have interlocking grains. They have a parallel arrangement of minerals along a particular orientation. They are hard and dense, with a crystalline structure.

They may be either foliated or non-foliated, depending on the type of metamorphism that occurred. What is Recrystallization? Recrystallization is the process of altering the form of a substance into a polycrystalline structure by dissolving the original material and then allowing it to solidify into a new crystalline structure. When a rock is exposed to high heat and pressure, it causes minerals in the rock to dissolve and recrystallize into new minerals, changing the space between grains in the rock. Recrystallization is a common process in metamorphic rocks where the original minerals are modified into new minerals. Therefore, the correct option is A. Recrystallization.

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Answer:

• pH = 3.0

• pH = 2.70

• pH = 3.61

• pH = 8.28

• pH = 1.40

Explanation:

El pH es una medida en química usada para determinar el grado de acidez o basicidad en una solución.

Se define como:

pH = -log₁₀ [H⁺]

El - logaritmo de la concentración molar de H⁺

Para las concentraciones de H⁺ dadas:

• [H+] = 0.001 M

pH = -log (0.001M) = 3

pH = 3.0

• [H+] = 0.002 M

pH = -log (0.002M)

pH = 2.70

• [H+] = 2.45X10-4 M

pH = -log (2.45X10-4 M )

pH = 3.61

• [H+] = 5.2X10-9 M

pH = -log (5.2X10-9 M)

pH = 8.28

• [H+] = 0.04 M

pH = -log (0.04M)

pH = 1.40

Answer: if anyone needs it <3

Explanation:

Answer:

120 cubic meters

Explanation:

Three-dimensional measurement is basically any unit of measurement cubed. Since grams is just to the first power, it is not considered three-dimensional. miles per hour is a fraction, so it is not a three-dimensional measurement of volume. 120 units are to the first power, so you are left with 120 cubic meters, which is a three-dimensional measurement of volume. Also, another way to solve this is to look at the types of measurement. The cubic meter is a measure of volume. Grams are a measurement of mass. Miles per hour is a measurement of speed. Units can be any type of measurement because you can substitute units instead of any measurement in questions.

Answer: The molarity of the solution formed by dissolving 10.0g of Ca(NO3)2 in 250 mL of aqueous solution is

0.244 M.

The molarity of the solution formed by dissolving 10.0g of Ca(NO3)2 in 250 mL of aqueous solution can be calculated using the following equation: Molarity (M) = (moles of solute / liters of solution).

In this case, we have 10.0 g of Ca(NO3)2, so we first need to convert it to moles. To do this, we multiply the grams of Ca(NO3)2 by its molar mass, which is 164.08 g/mol: 10.0 g × (1 mol/164.08 g) = 0.061 mol.

We also have 250 mL of aqueous solution, which is equivalent to 0.25 L. Plugging these values into the equation above gives us: M = (0.061 mol/0.25 L) = 0.244 M.

Therefore, the molarity of the solution formed by dissolving 10.0g of Ca(NO3)2 in 250 mL of aqueous solution is 0.244 M.

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(a) Before mixing in each part:

Part A: [Fe3+] = 0 M, [SCN-] = 0.002 M

Part B: [Fe3+] = 0.002 M, [SCN-] = 0 M

(b) The concentrations of the Fe3+ and SCN are different in the two parts of the experiment because they are added in different steps.

(a)

Part A: Before mixing, there is no Fe3+ or SCN- present. The Fe3+ is added to the SCN- solution to initiate the reaction, so their initial concentrations are both 0 M.

Part B: Before mixing, Fe(NO3)3 is added to water to form a solution with [Fe3+] = 0.002 M. KSCN is then added, but it does not initially contain any SCN-, so [SCN-] = 0 M.

(b)

The concentrations of Fe3+ and SCN- are different in the two parts of the experiment because they are added in different steps.

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The percent yield of isopentyl acetate is 71.23% when reacting 4.4 ml f acetic acid with 3.35 ml of isopentyl alcohol

Percentage yield can be defined as the ratio of the actual yield of a reaction to the theoretical yield of a reaction, multiplied by 100.

The percentage yield is calculated as follows:

Given data:

Volume of acetic acid used = 4.40 ml

Volume of isopentyl alcohol used = 3.35 ml

Volume of isopentyl acetate obtained = 3.25 ml

Density of acetic acid = 1.049 g/mL and its molar mass = 60.05 g/mol

Density of isopentyl alcohol = 0.809 g/mL and its molar mass = 88.15 g/mol

Density of isopentyl acetate = 0.876 g/mL and its molar mass = 130.19 g/mol

The balanced chemical equation for the reaction is:

C5H11OH + CH3COOH → CH3COOC5H11 + H2O

First, we need to determine which reactant is the limiting reactant. We can do this by calculating the number of moles of each reactant:

The mole ratio of acetic acid to isopentyl alcohol in the reaction is 1:1, so the limiting reactant is isopentyl alcohol because there are fewer moles of it.

The theoretical yield of isopentyl acetate can be calculated from the number of moles of limiting reactant:

Now we can calculate the percent yield:

The actual yield is given as 3.25 mL of isopentyl acetate, but we need to convert this to moles:

Therefore, the percent yield of isopentyl acetate is 71.23%.

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Answer: thinking

Explanation:

A mental disorder are ways of unusual feeling, or acting that are thinking. Therefore, option A is correct.

A clinically significant impairment in a person's intellect, emotional control, or behavior is what is known as a mental disorder. It is typically linked to distress or functional impairment in key areas.

Mental illness has many causes, not just one. Your genes and family history are only two examples of the many variables that can increase your risk for mental illness. Your life experiences, particularly if they occurred as a youngster, such as stress or a history of abuse.

Depression is the most prevalent mental condition, affecting an estimated 300 million individuals, and often affects women more frequently than males.

Thus, option A is correct.

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Answer:

a) 0.13 bar

b) 5.05 L

Explanation:

Let us take the mass of the mixture to be 100 g. Hence, 70% by weight of dioxygen corresponds to 70 g

Mass of dihydrogen = 100g - 70 g = 30g

Number of moles of dioxygen = 70g/32 g/mol = 2.2 moles of dioxygen

Number of moles of dihydrogen = 30g/2g/mol = 15 moles of dihydrogen

Total number of moles = 2.2 + 15 = 17.2 moles

Mole fraction of dioxygen = 2.2/17.2 = 0.13

Partial pressure = mole fraction * total pressure

Partial pressure of dioxygen = 0.13 * 1 = 0.13 bar

ii) number of moles in 8.8 g of CO2 = 8.8g/44g/mol = 0.2 moles

T = 31.1 + 273 = 304.1 K

P = 1 bar

V= ?

R = 0.083 bar L K-1 mol-1

From

PV=nRT

V = nRT/P

V= 0.2 * 0.083 * 304.1/1

V= 5.05 L

The metals you worked with in this simulation, the most likely to be found in pure form in nature is copper, silver, and gold.  While iron and aluminum are the least likely to be found in pure form in nature. Keep reading to learn more.

Elements that can be found in nature as a pure substance are known as native elements. Only a few metallic elements can be found in nature as pure substances, whereas the majority are found as compounds that are combined with other elements. Copper, silver, and gold are examples of native elements. The existence of these metals in their native state can be attributed to their relatively low reactivity and ability to resist chemical and physical changes

Iron and aluminum, on the other hand, are highly reactive metals and are therefore rarely found in nature in their pure state. Instead, they are found in combination with other elements such as oxygen, sulfur, or fluorine. Iron exists in minerals like hematite and magnetite, whereas aluminum is found in minerals such as bauxite and feldspar. In conclusion, copper, silver, and gold are the metals that are most likely to be found in pure form in nature, whereas iron and aluminum are the least likely to be found in pure form in nature.

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potassium group number is 1 and the period is 4

The alcohol that would produce 2,3-dimethylbut-2-ene through dehydration is 2,3-dimethylbutan-2-ol.

Dehydration of an alcohol involves the removal of a molecule of water from the alcohol, resulting in the formation of an alkene. In this case, we are looking for an alcohol that, upon dehydration, will produce 2,3-dimethylbut-2-ene.

The structure of 2,3-dimethylbut-2-ene suggests that it has a branched structure with two methyl groups on the second carbon. This means that the alcohol we need must have this same structure before dehydration.

The alcohol that fits this description is 2,3-dimethylbutan-2-ol. Upon dehydration, this alcohol would lose a molecule of water from the hydroxyl group on the second carbon, resulting in the formation of 2,3-dimethylbut-2-ene. Therefore, the correct answer is 2,3-dimethylbutan-2-ol.

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Answer:

C. A much larger amount of silk might be needed to produce the same effect

Explanation:

As you may know it will take a lot of silk to make bullet proof fabric out of it.

Answer:

I Guess C

Explanation:

The availability of spider silk is not enough for what is needed, so i believe C is the right answer. But that means that B is also a bit correct .

Answer:

Explanation:

A molecule, for example of water, contains 2 hydrogen atoms and 1 oxygen atom chemically bonded together and is the smallest building block of the chemical water. ... A mole is a certain quantity of molecules, specifically 6.02 x 10^23.

Hope this helps!

Direct contact between objects causes conduction or heat transfer. The heat is transferred inside the fluid during convection. Heat transfer in radiation happens by electromagnetic waves without the use of particles.

First, ascertain whether the two things are in contact. If they are, conduction is how heat is transferred between them. Determine whether there is a fluid medium, such as a liquid or gas, connecting the items if they are not in contact.

Evidence of heat transport is apparent. Convection is the phenomenon that causes the air to shimmer over radiators. Conduction is the phenomenon that causes you to feel warm when you place your hand on a spoon that has been sitting in a hot bowl of soup (radiation).

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Answer:

In the baking soda and vinegar reaction, the new substances created are carbon dioxide gas, water, and something called sodium acetate. Carbon dioxide gas was inside the bubbles you saw. The detergent did not change in the reaction.

Explanation:

Beryllium exists in Group 2 (Column 2) with the atomic number 4.

The atomic number of the next element in the group would be right below it, Magnesium (Mg). Magnesium contains the atomic number 12.

The charge number of an atomic nucleus is the chemical element's atomic number, also known as nuclear charge number. This is the number of protons present in the nucleus of each atom of that element, or the proton number, for conventional nuclei. Ordinary chemical elements can be uniquely identified by their atomic number.

The number of protons in an atom determines its atomic number, and isotopes have the same atomic number but different numbers of neutrons.

Beryllium exists in Group 2 (Column 2) with the atomic number 4.

The atomic number of the next element in the group would be right below it, Magnesium (Mg). Magnesium contains the atomic number 12.

The atomic number is the small number on the top left corner of the square of the element.

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