Which of the substances have a standard heat of formation ( δH∘f ) of zero?

Answers

Answer 1
All elements in their standard states (oxygen gas, solid carbon in the form of graphite, etc.) have a standard enthalpy of formation of zero, as there is no change involved in their formation.

Related Questions

What is the length of the radius, r? 10 units 12 units 20 units 24 units

Answers

Answer:12

Explanation:

Which of the following are possible benefits of alley cropping in the rain forest? select the two correct answers

Answers

The possible benefits of alley cropping in the rain forest include:

Increase in diversityMaintenance of soil nutrient.

What is Alley Cropping?

Alley cropping can be defined as a cropping technique that involves the planting of shrubs or trees in organized rows to maintain soil nutrients and increases biodiversity, especially in a rain forest.

Alley cropping also helps to control soil erosion.

Therefore, the possible benefits of alley cropping in the rain forest include:

Increase in diversityMaintenance of soil nutrient.

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What is the oxidation number for bromine in the molecule h2br2o6

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Taking into account the definition of oxidation number, the oxidation numbers for bromine in the molecule H₂Br₂O₆ is +5.

Definition of oxidation number

The oxidation number is the charge that an atom has; is an integer that represents the number of electrons an atom puts into play when it forms a given compound.

In other words, the oxidation number of an element is a value that indicates the number of electrons that element gains or loses when it combines with another.

Oxidation number determination

To determine the oxidation state of different elements it is necessary to know that:

The oxidation number of hydrogen in a compound is +1, except in metal hydrides, where is –1.The oxidation number of oxygen in a compound is –2, except in peroxides, where it is –1.

On the other side, the sum of the oxidation numbers of the existing elements in a chemical formula must add up to zero.

Then, considering the oxidation numbers of each element, multiplying it by the number of existing elements in the chemical formula and adding it and equaling it to zero, the value of the missing oxidation number can be obtained.

Oxidation number for bromine

In this case, the oxidation numbers of bromine is calculated as:

H₂Br₂O₆: 2× (+1) + 2× (oxidation numbers of nitrogen) + 6×(-2)= 0

2 + 2× (oxidation numbers of nitrogen) - 12= 0

2× (oxidation numbers of nitrogen) - 10= 0

2× (oxidation numbers of nitrogen) =10

oxidation numbers of nitrogen= 10÷2

oxidation numbers of nitrogen= +5

Finally, the oxidation numbers for bromine in the molecule H₂Br₂O₆ is +5.

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If a penny is made of 3. 11 grams of copper, how many atoms of copper are in the penny? show your calculations and answer with unit

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Answer:

Assuming a penny is made of pure copper Cu, then the molar mass of Cu can be used to determine the number of atoms in a penny.

The number of atoms in a mole is the Avogadro constant [math]N_{0}[/math]

The molar mass of Cu is [math]M_{Cu} =[/math] 63.546 grams per mole Cu

How Much Does A Penny Weigh? U.S. pennies since 1982 weigh 2.5 grams or 3.11 grams

Use the Moles to Grams Conversion Formula to solve for moles N[math]_{Cu}[/math]

Choose the mass of a penny to be [math]m_{penny}[/math] = 2.5 g for this question. (Repeat it with [math]m_{penny}[/math] = 3.11 g for yourself.)

Solution:

Find the number of moles of Cu in a penny [math]N_{Cu}[/math]

Find then number of atoms using

Explanation:

A mining company received government permission to purchase land for surface mining activities. this land was previously used by local ranchers for feeding their livestock. which of these plans prevents the permanent dislocation of local ranchers due to mining in this location?

Answers

Answer:

Feeding the Livestock

Explanation:

Feeding the Livestock prevents them from being able to use the location because now it's damaged.

Scott’s employer pays 70% of his health insurance premium and deducts the remainder from his paycheck. Scott is paid biweekly, and the annual premium is $8748. How much is deducted from his paycheck for health insurance?

Answers

The amount deducted from his paycheck for health insurance bi weekly is; $100.94

What is the amount deducted?

Since 70% of his health insurance premium is paid by his employer and the remaining deducted, then;

Scott's amount deducted per week for health insurance =  8,748 x 30% = $2,624.40

There are 52 weeks in a year and as such, amount deducted weekly is;

2,624.40/52 weeks = $50.47

Amount deducted bi weekly = 50.47 × 2 = $100.94

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Which statements apply to a certificate of deposit (cd)? choose two answers. It is always purchased as a short-term investment. It can be purchased from a banking institution. It is always purchased as a long-term investment. It can be purchased for almost any amount. It is purchased through an individual's employer

Answers

The two statements that refer to the certificate of deposits are:

It can be purchased from a banking institution.It can be purchased for almost any amount.

What is a certificate of deposit?

This is also referred to as time deposit. The deposit is a certificate that is issued to a person that is keeping money in a bank for a particular time period at a given rate of interest.

This certificate is gotten for almost any amount of money from the banks that are issuing them.

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Answer:

B. It can be purchased from a banking institution.

C. It can be purchased for almost any amount.

Explanation:

Which statements best describe differences in the style of the two works? the painting pays attention to details of kahlo’s physical appearance, while the poem does not. The poem portrays the painter as serious, while the painting does not. The poem reveals details that explain kahlo’s facial expressions, while the painting does not. The painting uses imagery that tells of kahlo’s connection to nature, while the poem does not

Answers

The painting pays attention to details of Kahlo's physical appearance, while the poem does not. Painting and poetry are artistic expressions.

What is painting?

Painting is an artistic expression aimed at visually expressing the characteristics of a given situation.

Painting can be employed to put emphasis on the physical characteristics of a person, landscape, etc.

Conversely, poetry refers to an artistic expression aimed at expressing feelings and emotions through texts.

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Answer:

the answer is C

Explanation:

on EDGE2022

can someone tell me what is AP​

Answers

Answer:

a sequence of numbers in which each differs from the preceding one by a constant quantity (e.g. 1, 2, 3, 4, etc.; 9, 7, 5, 3, etc.)

Red squirrels usually eat hazelnuts, but due to a reduction in their food source, they had to share resources with gray squirrels. The number of red squirrels decreased over time, and gray squirrels gradually replaced the red squirrels because they are better adapted to the environment. This is an example of

Answers

According to the context, gray squirrels gradually replaced the red squirrels due to a process of adaptation of these to the environment in which they are immersed, this is an example of natural selection.

What is natural selection?

It is the process of adaptation to the environment by which only organisms with certain characteristics reproduce.

Thus, natural selection is the process that favors the organisms best adapted to deal with their environment, allowing them to reproduce and transmit their characteristics to future generations.

Therefore, we can conclude that according to the context, gray squirrels gradually replaced the red squirrels due to a process of adaptation of these to the environment in which they are immersed, this is an example of natural selection.

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How many carbon atoms do glucose fructose and galactose have

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Answer:

each contain 6 carbon atoms

Explanation:

Choose the best spanish equivalent to the phrase. My mother hugs me every night. Mi madre me abraza cada noche. Mi madre abraza me cada noche. Mi madre abraza cada noche. Mi madre mí abraza cada noche

Answers

Answer:

Mi madre me abraza cada noche.

on edge its A :)

Explanation:

I'm sorry i'm late... but other peope can see this to help them :))

Answer: A. Mi madre me abraza cada noche.

Explanation: On Edge!

A marketing student is estimating the average amount of money that students at a large university spent on sporting events last year. He asks a random sample of 50 students at one of the university football games how much they spent on sporting events last year. Using this data be computed a 90% confidence interval, which turns out to be ($217, $677)

Answers

Answer: C) No conclusion can be drawn

Explanation:

Compare the functions f(x) and g(x) and choose the correct statement. F(x)=3x−2

Answers

The functions f(x) and g(x) are represented by their equations

The correct statement is that function g(x) is translated 2 units down to function f(x)

How to determine the correct statement

The functions are given as:

f(x) = 3x - 2

g(x) = 3x

Substitute 3x for g(x) in function f(x)

f(x) = g(x) - 2

The above means that:

Function g(x) is translated 2 units down to function f(x)

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Jayne has been tested to have an iq of 70. This suggests that she has a ____ level of intellectual disability

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Answer:

She has a low level of intellectual disability.

T is considered as one of earth’s large ecosystems, with its own kind of climate, soil, plants, and animals

Answers

Answer:

The Biosphere

Explanation:

A pension fund manager is considering three mutual funds. the first is a stock fund, the second is a long-term government and corporate bond fund, and the third is a t-bill money market fund that yields a sure rate of 5.5%. the probability distributions of the risky funds are:

Answers

The probability computed about the pension fund manager indicates that the standard deviation of the portfolio is 21.93%

How to calculate probability?

From the complete information, the covariance between fund returns will be:

= 34% × 25% × 0.11

= 0.9350%

The weight of the bond fund is given as 0.407281. Therefore, the weight of the stock fund in portfolio will be:

= 1 - 0.407281

= 0.592719

Therefore, the standard deviation will be:

= 23.56% × 0.9309471

= 21.93%

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In the passage, all of the following contrasts convey cynthia’s complex understanding of the divide between workers and management except

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In the passage, hungry versus satisfied didn't contrast convey Cynthia’s complex understanding of the divide between workers and management.

What is Sweat?

Sweat is a play that was written and produced in 2015 by American playwright Lynn Nottage. Also, it was centered on the working class (workers) of Reading in Pennsylvania and it won the Pulitzer Prize for Drama in 2017.

Cynthia was one of the characters that featured in Sweat among other characters such as Evan, Oscar, Brucie, Jason, Chris, Jessie, Tracey, and Stan.

Based on the passage, we can deduce that hungry versus satisfied didn't in anyway contrast convey Cynthia’s complex understanding of the divide between workers and management.

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What affects the distribution of metals and minerals on earth

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Answer:

This is due to the unequal resource distribution across the land and the distribution of resources depends upon the physical factors like the land and the climatic conditions. Some places are filled with more resources while some are filled with scare resources. The countries which have more resources are wealthy while the countries which do not have that much resources are not wealthy. The metals are also unevenly distributed on the earth’s crust and the most abundant metal is aluminum and silicon. Some of the distracted metals which are found deep in the earth’s crust and then extracted in the ore form from the mines. The most important reason for the uneven distribution of metals in Earth's crust are their physical factors like the climate, land and their topography.

Explanation:

Earth is made up of many minerals and metals. They are distributed unevenly because of the varying topography and climate across the lithosphere.

What is unequal distribution?

Earth is made of varying minerals and metals that are found in the mantle layer and vary in quantity as the distribution, pressure, and other physical factors are different in regions.

The topographical structure, climate, and land vary the mineral and metal distribution. Some areas have suitable climates, and pressure that supports more minerals making them rich than others.

Therefore, the topography and climate vary the mineral distribution.

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#SPJ2

Read "hope" by emily dickinson. Which theme is best supported by the poem? hope is not useful when someone faces challenges. Hope is not an emotion that people understand. Hope is best for people in only small doses. Hope can sustain people through difficult times

Answers

The theme that is best supported by the poem is that Hope can sustain people through difficult times.

What is the theme of the poem hope about?

The main Themes in “Hope” is the Thing that has to do with the Feathers. Here, Hope is said to be the major theme that is found in all of the poem.

Emily in her view or statement stated that hope is one that  resides in the hearts that is often used for good. It is one that tends to liberates us from pain and gives us the strength.

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Answer:

d. hope can sustain people through difficult times

Explanation:

What positive number when divided by its reciprocal
has a result of 4/25?

Answers

Explanation:

[tex]x \times x = \frac{4}{25} [/tex]

[tex] {x}^{2} = \frac{4}{25} [/tex]

[tex]x = \frac{2}{5} [/tex]

Nucleophilicity is a kinetic property. a higher nucleophilicity indicates that the nucleophile will easily donate its electrons to the electrophile and that the reaction will occur at the faster rate. the reaction rate also depends on the nature of the electrophile and solvent. rank the following reactions from fastest to slowest based on the nucleophilicity of the nucleophile.

Answers

The ordering of the reaction based on the based on the nucleophilicity of the nucleophile will be equation 2 > equation 1 > equation 3.

What is a reaction?

It should be noted that a chemical reaction simply means the change in chemicals to another form.

In this case, the ordering of the reaction based on the based on the nucleophilicity of the nucleophile will be equation 2 > equation 1 > equation 3.

This is depicted because tertiary amide is greater than secondary amide which is also greater than primary amide.

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Given △def, which is not equal to cos(f)? sin(f). Sin(d). Tan(f). Cos(d)

Answers

What’s the triangle

Answer:I believe it is tan(F) answer C

Explanation: sorry fam you just gotta trust ig

also if anyone wants to give a more mathematical answer here is the triangle they are using

Which word best describes a scientific hypothesis?

Answers

Answer:
Educated guess

When 1. 00 mole of nh4no3 dissolves in water, the enthalpy change is δh = + 25. 7 kj. What is the enthalpy change if 17. 5 grams of nh4no3 are dissolved in water?

Answers

The enthalpy change involved in the dissolution of 17. 5 grams of NH₄NO₃ in water is +5.47 KJ

Data obtained from the question 1 mole of NH₄NO₃ has an enthalpy change of +25 KJ 17.5 g of NH₄NO₃ =?

How to determine the enthalpy change for 17. 5 g of NH₄NO₃

1 mole of NH₄NO₃ = 14 + (1×4) + 14 + (3×16) = 80 g

Thus, we can say that:

80 g of NH₄NO₃ has an enthalpy change of +25 KJ

Therefore,

17.5 g of NH₄NO₃ will have an enthalpy change of = (17.5 × 25) / 80 = +5.47 KJ

Thus, the enthalpy change for 17.5 g of NH₄NO₃ is +5.47 KJ

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Evaluate three consequences of not applying for funding for your studies

Answers

The three consequences of not applying for funding for your studies are:

Inadequate money to pay for your education.Lack of focus in your be studies.Inability to buy necessary educational resources.

Consequences of not applying for funding for your studies Inadequate money to pay for your education: If you don't apply for finding, a student might find it difficult to pay for his fees.

Lack of focus in your be study: A student who is experiencing difficulty in paying fees will have a divided attention and won't focus on studies.

Inability to buy necessary educational resources: The student will find it difficult to but the necessary learning resources that will aid their studies.

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A wheel is turning about an axis through its center with constant angular acceleration. Starting from rest, at t = 0, the wheel turns through 8. 20 revolutions in 12. 0 s. At t = 12. 0 s the kinetic energy of the wheel is 36. 0 j. For an axis through its center, what is the moment of inertia of the wheel?

Answers

Answer: 0.975 m^2

Explanation:

θ = 0.5αt^2

8.20 revolutions = 8.20 x 2π = 51.52 rad

51.52 = 0.5α(12)^2

α = 0.716 rad/s^2

ω = αt = 0.716(12) = 8.592 rad/s

KE = 1/2Iω^2

36 = 0.5I(8.592)^2

I = 0.975 m^2

Therefore, the moment of inertia of the wheel is approximately 0.975m^2

By applying the strategy of containment the united states hoped to prevent the

Answers

They hoped to prevent the spread of communism

Which of the following types of evidence is considered the most accurate in classifying organisms, according to the majority of scientists?

Answers

Answer: Molecular

EXPLANATION;form and evolutionary relationships.

What technique did the artist of the painting above use to capture the light reflecting on the water?

Answers

Answer:

I believe the answer is rapid brushstrokes.

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