Which substance has a standard enthalpy of formation of zero?.

Answers

Answer 1

Answer: In its natural condition, a pure element


Related Questions

Why must chemical equations be balanced? (Choose all that apply.)

Two substances must make a new substance.
All atoms on both sides of an equation must be the same.
All atoms on both sides of an equation must be in equal amounts.
It is needed in order to add coefficients.
It will satisfy the law of conservation of mass.

Answers

Answer:

It will satisfy the law of conservation of mass.

Two substances must make a new substance.

All atoms on both sides of an equation must be the same.

Explanation:

Stay safe, stay healthy and blessed.

Have a blessed day !

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Answer the question PLS 100 points!!!

Answers

1atm=760mm Hg

Now

1.36atm1.36(760)1033.6mm Hg

Done!

We know

[tex]\boxed{\sf 1atm=760mmHg}[/tex]

So convert now

1.36atm1.36×760mmHg136/100(760)mmHg1033.6mm Hg

Which statement is NOT true about the human sperm cell?


composed of a "head" and "tail"


one of the smallest cells in the male body


the flagella(tail) is used for motility


all of the above are true

Answers

Answer:

all of the above

Explanation:

What is the minimum internal cooking temperature for ground beef?.

Answers

One hundred sixty degrees Fahrenheit

composed of an organic matrix, which gives it tensile strength; it is composed an inorganic calcified matrix, which gives it hardness. __________ is a condition, whereby a certain amount of bone density is loss; it then involves loss of both matrices.

Answers

 Bone is composed   calcified matrix, which gives it hardness. The loss of this bone hardness is called Osteopenia.

Loss of bone strength

Bone is an organic matrix that is highy reinforced by inorgaanic minerals  such as calcium. Bone is known to be intricated laced in a calcified matrix, which gives it hardness.

The loss of this bone density and consequent loss of the rigidity of the bone is called Osteopenia.

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Please answer questions 7-13 for alpha and beta decay. I need help!!!!!!!

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where are the questions?

Some greenhouse gases, such as fluorocarbons (CFCs, HFCs, PFCs, etc. ), are human-made. Others, such as water, methane, and carbon dioxide, are naturally produced. Which type of greenhouse gas (human-made or natural) is more difficult to control and eliminate? Which types are easier? In three to five sentences, provide evidence for your argument

Answers

The green house gases are those gases that are known to prevent the escape of infrared rays.

What are green house gases?

The green house gases are those gases that are known to prevent the escape of infrared rays and ultimately lead to an increase in the temperature of the earth.

These green house gases could be natural or artificial. The natural greenhouses gases are more difficult to control because they can alaso be produced in natural processess that are not subject to human control.  

For instance, there are process in the ocean that produce methane and this gas is also produced by decomposition in nature. This makes the control of the gas not entirely within the control of man.

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What is Arrhenius's definition of an acid?
a substance that dissociates in water to produce hydroxide ions (OH)
O a substance that dissociates in water to produce hydrogen ions (H+)
O any substance that can donate hydrogen ions (H+).
O
any substance that can accept hydrogen ions (H+)

Answers

A substance that dissociates in water to produce H+ ions

Arrhenius: an acid is a substance which when dissolved in water will release H⁺ ions.

HₓY(aq) ⇒ xH⁺(aq) + Yˣ-(aq)

Isaac is baking a cake and needs to add flour weighing 5.85 oz to the mixture. if there are 28.3495 g in one ounce, how many grams of flour does he need to add? a. 4.85 g b. 20.64 g c. 158.69 g d. 165.84 g

Answers

The quantity of floor needed by the Isaac for making the cake will be equal to 165.844575 gram

What is a Unit Conversion system?

Unit conversion is a multi-step process that involves multiplication or division by a numerical factor, selection of the correct number of significant digits, and rounding.

Given that

1 oz =28.3495 gram

Therefore 5.85 oz will give x gram

X gram is what we are looking for

X gram= 5.85 oz× 28.3495g/1

Xg= 165.844575 gram

Approximately 165.8446 gram

Thus, Isaac needs to add 165.8446g of flour to the mixture to make 5.85 oz

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What would the concentration of an NaOH solution be if 25 moles were used and 50 L were used?

0.5 M
0.5 M

2 M
, 2 M

1250 M
1250 M

25 M

Answers

Answer: 0.5 M

Explanation:

How do gravitational forces impact the motion of earth and moon?

Answers

Answer:

The Gravitational Force of the Earth and Moon on Each Other. According to Newton's Third Law of Motion, the Law of Action and Reaction, if the Earth exerts a force on the Moon, the Moon must exert an equal and opposite force on the Earth.

The ideal gas law is equivalent to Charles's law when

a) volume equals 22.4 L
b)R equals 0
c)number of moles and temperature are constant
d)number of moles and pressure are constant

Answers

The ideal gas law is equivalent to Charles's law when number of moles and pressure are constant (option D)

Ideal gas equation

PV = nRT

Where

P is the pressure V is the volume n is the number of mole R is the gas constant T is the temperature

Charles' law

Charles' law states as follow:

V₁ / T₁ = V₂ / T₂

Where

V₁ is the initial volume T₁ is the initial temperature V₂ is the new volume T₂ is the new temperature

How to relate ideal gas equation to Charles' law

PV = nRT

Divide both side by T

PV / T = nR

Divide both side by P

V / T = nR / P

Let nR / P be costant

V / T = constant

Thus,

V₁ / T₁ = V₂ / T₂

From the above illustrations, we can conclude that the ideal gas equation will become Charles' law equation if the number of mole and pressure are constant (Option D)

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which of the following charecteristics will not help u tell whether two solids are the same or are diferent substances?

Answers

Answer:

D. Melting point

Explanation:

A. Color

B. Hardness

C. Shape

D. Melting point

How many moles of calcium acetate are needed to react with 5.00 moles of sodium carbonate?

Answers

Answer:

[tex]5.00 moles Ca(C_2H_3O_2)[/tex]

Explanation:

First find the chemical formula for this reaction:

[tex]Ca(C_2H_3O_2) + Na_2CO_3 - > CaCO_3 + 2NaC_2H_3O_2[/tex]

Knowing from the chemical formula that one mole of calium acetate will react with one mole of sodium carbonate can be used to find how many moles of calcium acetate react with 5.00 moles of sodium carbonate:

[tex]5.00 molNa_2CO_3 * \frac{1 molCa(C_2H_3O_2)}{1 mol Na_2CO_3} = 5.00 mol Ca(C_2H_3O_2)[/tex]

Remember that your answer needs to have three significant figures.

Which statement below is true?

The mass of each planet is different, so they each orbit their own moons.

The mass all the planets together is greater than the mass of the sun.

The mass of all planets is the same, so they all orbit the Sun.

The mass of each planet is less than that of the Sun, so they all orbit the Sun.

Answers

Answer:The mass of each planet is less than that of the Sun, so they all orbit the Sun.

Explanation:

What is the equilibrium expression for 2NO+Br2⇌2NOBr?

A.) [NO]2[Br2]/[NOBr]2
B.) [NOBr]2/[NO2][Br]2
C.) [NO2][Br]2/[NOBr2]
D.) [NOBr]2/[NO]2[Br2]

Answers

Explanation:

D mole is a power. .......

[NOBr]2/[NO]2[Br2] is the equilibrium expression for 2NO+Br2⇌2NOBr. Therefore, the correct option is option D.

What is equilibrium?

When the observable qualities, such as colour, pressure, temperature, concentration, etc. do not vary, the process is said to be in equilibrium. As "balance" is the definition of the word "equilibrium," it follows because a chemical reaction reflects a balance among the substances and outcomes involved in the reaction.

In some physical processes, such as the melting of ice at 0°C, where both the two substances are present at equilibrium, the equilibrium state can also be observed. Physical equilibrium refers to the equilibrium that results from physical processes like the melting of solids.  [NOBr]2/[NO]2[Br2] is the equilibrium expression for 2NO+Br2⇌2NOBr.

Therefore, the correct option is option D.

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True or false, Atoms with 5 to 8 electrons want to "donate"  or get rid of them.

Thank you!​

Answers

I would say false but I’m not sure

The central region of an atom where its neutrons and protons are is its:.

Answers

This is considered the atomic center

how many protons, neutrons and electrons? please help

Answers

Proton number is the same as the atomic number.Co has atomic number 27
Hence it has 27 protons

In a neutral atom the electrons equals the protons but this is an ion (cation that has given out 2 electrons) and so has electrons being (27 - 2)= 25

Neutron number is the difference between the mass number and proton number.i.e neutrons = 62-27 =35

Protons = 27
Electrons = 25
Neutrons = 35

Calculate the vapour density of a
diatomic gas X, if its relative mass is 16​

Answers

From the information, the vapor density of gas X is obtained as 8. The vapor density is half of the relative molecular mass  of the compound.

What is vapor density?

The term vapor density is defines as half of the relative molecular mass of a compound. Now we have the relative molecular mass of the compound as 16.

It the follows that the vapor density of the compound must be 16/2. Hence, the vapor density of the diatomic gas X is 8.

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Which represents the correct equilibrium constant expression for the reaction below? upper c u (s) plus 2 upper a g superscript plus (a q) double-headed arrow upper c u superscript 2 plus (a q) plus 2 upper a g (s). k e q equals startfraction startbracket upper c u endbracket startbracket upper a g superscript plus endbracket superscript 2 over startbracket upper c us superscript 2 plus endbracket startbracket upper a g endbracket superscript 2 endfraction. k e q equals startfraction startbracket upper c u superscript 2 plus endbracket startbracket upper a g endbracket superscript 2 over startbracket upper c u endbracket startbracket upper a g superscript plus endbracket superscript 2 endfraction. k e q equals startfraction startbracket upper a g superscript plus endbracket superscript 2 over startbracket upper c u superscript 2 plus endbracket endfraction. k e q equals startfraction startbracket upper c u superscript 2 plus endbracket over startbracket upper a g superscript plus endbracket superscript 2 endfraction.

Answers

The correct equilibrium constant expression for the given chemical reaction is Keq = [Cu²⁺] / [Ag⁺]².

What is equilibrium constant?

Equilibrium constant of any reaction at the equilibrium state will be define as the ratio of the concentration of products to the concentration of the reactants.

Given chemical reaction is:

Cu(s) + 2Ag⁺(aq) ⇄ Cu²⁺(aq) + 2Ag(s)

Equilibrium constant for the above reaction will be written as:

Keq = [Cu²⁺][Ag]² / [Cu][Ag⁺]²

But in the above reaction at the product side silver is present in pure solid form and at the reactant side copper is present in pure solid form and concentration of these elements equals to one in equilibrium state, so that equation becomes:

Keq = [Cu²⁺] / [Ag⁺]²

Hence equilibrium expression for given reaction is Keq = [Cu²⁺] / [Ag⁺]².

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Answer: D

Keq = [Cu²⁺] / [Ag⁺]²

Which of the following converts chemical energy to electrical energy? Question 2 options: Camp fire Person eating food Battery Automobile

Answers

Answer:

battery

Explanation:

the answer is C

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What is TVEL (nuclear fuel cycle) special features that use Nuclear Technology?

Answers

Answer:

TVEL is developing mixed-oxide (MOX) fuel and REMIX fuel, with both using recycled uranium together with plutonium. This is the dual-component approach. "We're very actively engaged in this and right now it is cost-intensive,"

Answer:

Brainliest pls

Explanation:

The nuclear fuel cycle consists of several steps: mining, milling, conversion, enrichment, fuel fabrication, and electricity generation.

What happens to the electrons of a reducing agent during a reaction?
Electrons are doubled
Electrons are lost
Electrons are gained
Electrons are held

Answers

I think it is either b or d

Answer:

A I DID THIS BEFORE

Explanation:

What are some common isotopes of mercury?

Answers

Answer:

The three most stable isotopes of hydrogen: protium (A = 1), deuterium (A = 2), and tritium (A = 3).

Protium, the most common isotope of hydrogen, consists of one proton and one electron. ...

A deuterium atom contains one proton, one neutron, and one electron.

Explanation:

In redox reactions, electrons are ____.

A)shared
B)lost
C)transferred
D)not needed

Answers

Answer:

C

Explanation:

This is the only option that gives the right option as in redox reaction electron are lost and gained by different atoms. Not shared or not needed are not right

A student in your lab volunteers to enter a hypoxic breathing chamber for 10 minutes, and his alveolar PO2 drops to 50 mm Hg. What other change would occur

Answers

If u add the picture I can help. Pictures help me understand better :D !!

Which of the following represents enthalpy on this graph?



Question 1 options:

1


2


3


4

Answers

exothermic reaction is reactants accomphen by evolution of heat

Consider the following equilibrium: upper c upper o (g) plus 2 upper h subscript 2 (g) double arrow upper c upper h subscript 3 upper o upper h (g). k subscript e q equals 26. which statement about this system is true? if the equilibrium concentration of co is 3.4 × 10–1 m, and the equilibrium concentration of h2 is 6.8 × 10–1 m, the equilibrium concentration of ch3oh is

Answers

The equilibrium concentration of CH3OH will be equal to 0.089 if the equilibrium concentration of co is 3.4 × 10–1 m, and the equilibrium concentration of h2 is 6.8 × 10–1 m

What is equilibrium concentration?

An equilibrium concentration is a state when the rate of forward reaction in a chemical reaction becomes equal to the rate of backward reaction

Step 1:

The balanced equation for the reaction is given below:

H2O + Cl2O <=> 2HClO

Step 2:

Data obtained from the question. This includes:

Concentration of H2O, [H2O] = 0.077 M

Concentration of Cl2O, [Cl2O] = 0.077 M

Concentration of HClO, [HClO] = 0.023 M

Equilibrium constant, K =?

Step 3:

Determination of the equilibrium constant. This is illustrated below:

The equilibrium constant for the above reaction is given below:

K = [HClO]^2 / [H2O] [Cl2O]

K = (0.023)^2 / (0.077 x 0.077)

K = 0.089

Therefore, the equilibrium constant for the above reaction is 0.089

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question for smart people

Answers

A)pH⇢ 9.50pOH⇢14 - pHpOH⇢ 14 - 9.50pOH⇢4.50

B)

9.50 = - log [H3O+]-9.50 = log [H3O+][H3O+] = 10^-9.50 [H3O+] = 3.16 x 10^-10 M

C)The solution is basic in nature as it's pH >7

#a

pH+pOH=14pOH=14-9.50pOH=4.50

#b

[H+] be x

-logx=9.50logx=-9.5x=10^{-9.5}x=3.2×10^-10M

#c

basic as pH is 9.5>7

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