A sample of a substance was heated strongly in a crucible, and the sample increased in mass.

This is evidence that

A. A gas had been evolved.

B. The substance had melted.

C. The substance had sublimed.

D. A chemical change had taken place.

O E. A change of state had occurred.

When a liquid changes to a gas, the molecules in the room gain enough energy to break the bonds that hold them together in the liquid state.

What are Molecules?

Molecules are the smallest unit of matter that still has the properties of a particular substance. They are made up of two or more atoms that are bonded together. Molecules can be covalent, meaning the atoms in the molecule share electrons, or ionic, meaning one atom has donated electrons to the other.

This energy comes from an increase in temperature, which causes the molecules to move faster and farther apart. As the molecules move around and expand, they fill the room with a vapor or gas.

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Answer:

13=C

14=D

Explanation:

I cant explane the right formula but my answer is correct

If it takes 75.0mL of a 2.50M HCl solution to neutralize 55.0mL of a base unknown concentration, the concentration of a unknown basic solution is 1.83M.

Molarity in chemistry is the concentration of a substance in solution, expressed as the number moles of solute per litre of solution.

The molarity of two solutions in a neutralization reaction can be calculated as follows:

CaVa = CbVb

Where;

According to this question, 75.0mL of a 2.50M HCl solution is required to neutralize 55.0mL of a base unknown concentration. The concentration of the solution can be calculated as follows:

2.5/75 = Cb/55

0.0333333333 × 55 = Cb

Cb = 1.83M

Therefore, 1.83M is the molarity of the unknown basic solution.

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To reduce the risk when working with concentrated acids and bases, it is important to never work with them directly, work with large volumes, neutralize them, and dilute them.

a) Never work with it - Concentrated acids and bases can be extremely dangerous and should never be handled directly.

b) Work with large volumes - In order to reduce the risk, it is important to always work with large volumes of the acid or base so that the concentration is lower.

c) Neutralize it - It is important to neutralize both acids and bases before disposing of them in order to reduce the risk of harm to people or the environment.

d) Dilute them - Diluting acids and bases by adding water can reduce their concentration, making them safer to work with.

To reduce the risk when working with concentrated acids and bases, it is important to never work with them directly, work with large volumes, neutralize them, and dilute them.

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1 mole of any gas occupies 22.4 L volume. The molecular weight of water is 18 grams. Thus 18 gram of Water will also occupy 22.4 L.We know that at STP one mole of any gas occupies 22.4litres . It means that one mole of hydrogen also occupies 22.4litres of volume at STP. So 10moles of hydrogen gas will occupy =22.4×10=224litres of volume at STP.

Heat engine is a system that converts thermal energy into a form of useful mechanical or electrical energy.

In thermodynamics, the heat engine is a system which is able to convert the heat or thermal energy into mechanical or electrical energy which can be used in order to perform mechanical work. This is achieved by bringing the a particular working substance to a lower state temperature from a higher state temperature.

There are a different types of heat engines in which the Carnot engine possesses the maximum efficiency. Some examples of heat engines are firearms, thermal power station etc.

Hence, the correct option is b. heat engine.

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3.125 moles of oxygen are present in 50 g.

A mole is the volume of a substance that contains 6.022 X 1023 of the substance's particles, atoms, ions, molecules, etc. A mole is a unit for counting molecules, ions, or atoms. Divide the given mass of an element by its molar mass to find the number of moles in that quantity.

The atomic weight of an element, or its relative atomic mass, on the periodic table, expressed in g/mol, is its molecular mass.

The molar mass of oxygen is 16 g/mol, and there are 3.125 moles in a given amount of mass and molar mass.

Consequently, 3.125 moles of oxygen are present in 50 g.

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Answer:

Mass of lithium = 0.22 gram (Approx.)

Explanation:

Given:

Change in temperature Δt = 44.1 °c  

Absorbing heat Q = 713.5 joules

Specific heat capacity of lithium c = 3.58 J/(g°C)

Find:

Mass of lithium

Computation:

We know that;

Q = mcΔt

m = cΔt / Q

Mass of lithium = (3.58)(44.1) / (713.5)

Mass of lithium = (157.878) / (713.5)

Mass of lithium = 0.2212

Mass of lithium = 0.22 gram (Approx.)

Molarity of 122.5 grams of AlCl₃ in 1 Liter solution is 0.921 M.

Molarity is defined as no. of moles of solute present in per liter of solution and it is represented as:

M = n/V

First we have to calculate the moles of AlCl₃ and it can be calculated as:

n = W/M, where

W = given mass of = 122.5g

M = molar mass of = 133g/mole

n = 122.5 / 133 = 0.921 moles

Now molarity in 1 liters can be calculated as:

M = 0.921/1 = 0.921M

Hence, molarity of AlCl₃ is 0.921M.

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The molecular weight of the unknown compound is 80.864g.

Only the solute's concentration affects freezing point depression; the solute's mass or chemical composition have no bearing. When it's cold outside, salt is often used to prevent ice from forming on roads by lowering the freezing point of water.

Depression in freezing point is Kb x m

T(f) - T  = Kb x  m

48.1 - 35.8 =  9.8 x m

m = 1.255

m = moles of solute x 1000/mass of solvent

moles of solute x 1000 / 10.0090  = 1.255

moles of solute = 0.0125

moles = mass / molar mass

1.0108  / molar mass  = 0.0125

molar mass =  1.0108 / 0.0125

molar mass = 80.864

so the molecular weight is 80.864g.

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Answer:

b, H2O(s) r H2O(g)

Explanation:

entropy is heat, so increase in heat would mean water gets evaporated or melted, or both in this case. so the only choice above that showed increase in heat is from solid(ice) to gas(water vaper) due to increase in heat in the reaction.

Geologists use rock samples including sedimentary rocks as direct evidence and seismic waves as indirect evidence.

They are the types of rocks which are formed as a result of accumulation of minerals or organic particles at the surface of the earth.Sedimentation is the name given to a collective process which cause the particles to settle.

The study of sedimentary rocks is useful in civil engineering and as important sources of coal, fossil fuels and ores.The color of sedimentary rock is often determined by iron content and sometimes due to the presence of organic matter.

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Yes, if we add a lot of H₂, the value of K will start falling, which will cause the reaction to move forward. The minimum pressure of H₂ needed to reverse it is 3.598atm.

The force applied per area is referred to as pressure.

ΔG° = -RT ln(K)

34000 = 8.314(273 + 1126)ln(K)

ln(K) = 2.9231

K = [tex]e^{2.9231}[/tex] = 18.834

Since the container doesn't contain any H₂ gas, K will therefore start out at infinity. The reaction will move in the opposite direction in order to reach equilibrium. Consequently, the pressure of N₂ will initially rise.

Yes, if we add a lot of H₂, the value of K will start falling, which will cause the reaction to move forward.

The answer is therefore yes.

K = (5.97)²/0.0406(PH₂)³

K = 3.598atm.

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Answer:

assalam o aalaikum

Explanation:

o

90

180

270

360 x

-1

Given that 0 find the value of a and the value of b.

(2 marks)

.

In literary classes, the three most popular types are verbal irony, dramatic irony, and situational irony. When a speaker or narrator says something that contradicts what they mean, what they intend, or what the context necessitates, this is called verbal irony.

One thing is expressed while another is meant in an ironic statement. For example, on a chilly, wet gray day, you would exclaim, "What a gorgeous day!" Alternatively, if you were suffering from a severe case of food sickness, you may respond, "Wow, I feel terrific today." "ffers points of view and ideas that are, at most, intriguing... However, it does not reach the truth." Ronagh and Souder are particularly concerned with scientific assertions that are not meant to be taken seriously.

Here,

The three most common varieties in literary studies are verbal irony, dramatic irony, and situational irony. Verbal irony occurs when a speaker or narrator says something that contradicts what they mean, what they intend, or what the context requires.

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Answer:

Explanation:

Answer:

i think its the first one

Explanation:

i could be wrong

Aspartyl-phenylalanine-1-methyl ester, also known as the methyl ester of the dipeptide of the amino acids aspartic acid and the essential amino acid phenylalanine, is the term for an artificial, non-carbohydrate sweetener.

Sweeter than sugar flavoring ingredient that is broken down into phenylalanine and aspartic acid. Aspartyl-phenylalanine-1-methyl ester, also known as the methyl ester of the dipeptide of the amino acids aspartic acid and phenylalanine, is a synthetic, non-carbohydrate sweetener known as aspartame. Aspartic acid is a methyl ester of a dipeptide made up of aspartic acid and phenylalanine, two amino acids. Along with methanol, aspartame is entirely hydrolyzed to its individual amino acids in the digestive system. In the body, aspartame is hydrolyzed into aspartic acid (40%) phenylalanine (50%) and methanol (10%). An amino is aspartic acid.

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Answer:

The basic principle of this type of distillation is that different liquids boil and evaporate at different temperatures. So when the mixture is heated, the substance with a lower boiling point starts to boil first and convert into vapors. Let consider a liquid-liquid mixture of A and B where A is more volatile than B this mixture can be separated by the following process:

Explanation

Answer: The concentration of nitrogen gas in parts per million is 7.99 ppm.

Explanation:

Solute is defined as the component of the solution present in a smaller proportion while the solvent is defined as the component of the solution present in a larger proportion.

Concentration in ppm (parts per million) represents the amount of solute in milligrams present per kilograms of solution.

[tex]\text{Concentration in ppm}=\frac{\text{Mass of solute (in mg)}}{\text{Mass of solution (in kg)}}[/tex]

                                       OR

[tex]\text{Concentration in ppm}=\frac{\text{Mass of solute (in grams)}}{\text{Mass of solution (in grams)}}\times 10^6[/tex]      ......(1)

Given values:

Mass of solute (nitrogen gas) = 0.008 g

Mass of solvent (water) = 1000 g

Mass of solution = [0.008 + 1000] g = 1000.008 g

Plugging values in equation 1:

[tex]\text{Concentration in ppm of nitrogen gas}=\frac{0.008g}{1000.008g}\times 10^6\\\\\text{Concentration in ppm of nitrogen gas}=7.99 ppm[/tex]

Hence, the concentration of nitrogen gas in parts per million is 7.99 ppm.

Lystrosaurus and Glossopteris are two pieces of fossil evidence support the idea of continental drift.

One of the geologist's first theories about how continents moved over time was continental drift.  The science of plate tectonics has been largely supplanted the hypothesis of the continental drift. Alfred Wegener has been most closely associated with the continental drift idea. Wegener released a paper in the early twentieth century describing his notion that continental landmasses were "drifting" across the Earth, occasionally ploughing through seas and into one other. He developed the term "continental drift" to describe this process.

Wegener found similarities in the coasts of eastern South America as western Africa and hypothesised that those countries had originally been part of a supercontinent called Pangaea, which had separated and travelled many kilometres away over geologic time. He also mentioned nearly comparable fossil creatures and rock layers that happened on vastly different continents. Colbert discovered Lystrosaurus fossils in the Transantarctic Mountains of Antarctica. Such fossils belonged to something like a species previously discovered in Africa, proving that the world's two most distant continents were formerly linked.

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Answer: C. Lystrosaurus and Glossopteris

Explanation:

Helium: The new volume of the balloon is 0.6182 L.

Colorless, odourless , tasteless, inert, non-toxic helium is a monatomic gas. It is the lightest element in the periodic table and the second most abundant element in the universe.

The new volume of the balloon can be calculated using the ideal gas law, which states that PV = nRT, where P is the n represents the number cubic moles of gas, V represents the volume, R is the real gases constant, and the temperature is T.

First, we need to calculate the number of moles of helium in the balloon after the additional 0.670 grams have been added:
n = 0.670 g He/4.003 g/mol = 0.167 mol

The total number of moles in the balloon is now 0.267 mol. We can use the ideal gas law to calculate the new volume:

V = (0.267 mol)(0.0821 L·atm/K·mol)(273 K)/1 atm = 0.6182 L

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Answer:

The reaction rate in mol/sec is 0.005.

Explanation:

To determine the reaction rate in mol/sec, you need to first determine the number of moles of H₂ gas produced in the reaction. The volume of a gas at STP (standard temperature and pressure) is directly proportional to the number of moles of the gas, so you can use the volume of H₂ gas produced to calculate the number of moles.

At STP, 1 mole of a gas occupies a volume of 22.4 L. Therefore, the number of moles of H₂ gas produced in the reaction can be calculated as follows:

moles H₂ = 4.48 L / 22.4 L/mol = 0.2 mol

To determine the reaction rate in mol/sec, you need to divide the number of moles of H₂ gas produced by the time it took for the reaction to occur:

reaction rate (mol/sec) = 0.2 mol / 40 sec = 0.005 mol/sec

So, the reaction rate in mol/sec is 0.005.

Answer:

Explanation:

NaNO3

Just do a double displacement reaction, this is what you get (plus water)

The reaction shifts to the left, and the concentrations of SO2(g) and O2(g) increase.

Simply put, the system will seek to stay at equilibrium by shifting to compensate for change.

Complicatedly put, consider the fact that K (the equilibrium constant) is the concentration of products raised to their coefficients over the concentration of the reactants raised to their coefficients. If we write an expression for K, we get this:

[tex]K=\frac{[SO_3]^2}{[SO_2]^2[O_2]}[/tex]

If we assume that, at equilibrium, all of the substances have a concentration of 1 molar, we get that

[tex]K=\frac{[1]^2}{[1]^2[1]}=1[/tex]

If we increase SO3, K will increase. This means the system has now been removed from equilibrium. For example, if you add another mole of SO3, you get

[tex]Q=\frac{[2]^2}{[1]^2[1]}=4[/tex]

(Q is just K, but not at equilibrium.)

Since the system wants to stay at equilibrium, it will work to restore equilibrium. The only way to do this is to increase the value of the reactants (the bottom numbers), meaning the reaction will shift to the left. Worded differently, when Q>K, the reaction will shift left.

2,2-Dimethylbut-1-yne .The alkyne name is formed using the IUPAC nomenclature system.

First, the length of the longest continuous carbon chain (containing the triple bond) must be identified. In this case, it is a four-carbon chain (but-).

Second, the location of the triple bond must be determined. In this case, it is located on the first carbon atom so the prefix 1- is used.

Third, the substituents must be listed in alphabetical order. In this case, there are two methyl groups (2,2-dimethyl).

The final name is 2,2-Dimethylbut-1-yne.

2,2-Dimethylbut-1-yne .The alkyne name is formed using the IUPAC nomenclature system.

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Answer: d

Explanation: I got it right

Benzene (C6H6) burns in air to produce carbon dioxide and liquid water.The heat released in KJ per gram of the compound reacted with oxygen is -41.83 KJ.

Heat is the result of the movement of kinetic energy within a material or an item, or from an energy source to a material or an object. Radiation, conduction, and convection are the three mechanisms through which such energy can be transferred.

The movement of minuscule atoms, molecules, or ions in solids, liquids, and gases produces heat energy. From one thing to another, heat energy can be exchanged. Heat is the flow or transfer that occurs as a result of the temperature differential between two objects.

Reaction as follows;

2C6H6 + 15O2 → 12CO2 + 6H2O

2x49.04   2x10       12x-393.5  6x-285.8

= [ 12(-393.5 )+6(-285.8) ] - [ 2(49.04)+(2x10) ]

= - 6936.8 - 98

= - 6534.8 KJ/mole

Per gram of benzene

= ( -6534.8 KJ / 2 mole of C6H6) (1 mole of C6H6 / 78.108g )

= -41.83 KJ / mole

Thus, The heat released in KJ per gram of the compound reacted with oxygen is -41.83 KJ.

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