Which substance has Delta.Hf defined as 0 kJ/mol?
A. H2O (s)
B. Ne (l)
C. F2 (g)
D. CO2 (g)

Answers

Answer 1
B is correct answer have a good day
Answer 2

Answer:

its actually c

Explanation:


Related Questions

help ! thank u / ill give brainlist !

Give two examples of energy transformations that occur throughout the journey to or on the planet.

Answers

Answer:

Our bodies convert chemical energy in our food into mechanical energy for us to move.

An electric fan transforms electrical energy into kinetic energy

Reword it tho

Hope this helps!!

it refers to the length of the entire path the object travelled

Answers

Answer:

Path length is the overall distance traveled following the path of where the object travel. ... Displacement is the distance from the starting point of the object to its final point irregardless where it travels.

how many cats are in the word

Answers

Answer: more than 70,00 and most of that population is living on the streets

identify two conjugate base for each compound HCN and HBr

Answers

The conjugate base of HCN is CN^-

The conjugate base of HBr is Br^-

What is the thermal efficiency of an engine that takes n moles of diatomic ideal gas through the cycle

Answers

Answer:

The thermal efficiency of an engine is [tex]0.15[/tex] that is 15%

Explanation:

Specific heat of a gas at constant volume is

[tex]C_{v}=\frac{fR}{2}[/tex]

here, [tex]f=[/tex]degree of freedom

[tex]R=[/tex]universal gas constant

Thermal efficiency of a cycle is

[tex]\frac{total workdone}{gross heat absorbed}[/tex]

Gross heat absorbed is amount of heat that absorbed.

ω[tex]=P_{o} V_{o}[/tex]

[tex]Q_{AB}=[/tex]Δ[tex]V_{AB}+[/tex]ω[tex]_{AB}[/tex][tex]=nC_{v}(T_{f}-T_{i} )[/tex]

       [tex]=n\frac{f}{2}(RT_{f}-RT_{i} )[/tex][tex]=\frac{f}{2}(P_{o}V_{o} )[/tex]

[tex]Q_{BC}=n(\frac{f}{2}+1 )R(T_{f}-T_{i} )[/tex]

       [tex]=(\frac{f}{2} +1)(4P_{o}V_{o}-2P_{o}V_{o} )[/tex]=[tex]=(\frac{f}{2}+1)2P_{o}V_{o}[/tex]

[tex]Q_{CD}=-ve and Q_{DA}=-ve[/tex]    these 2 are not the part of gross heat

η[tex]=\frac{P_{o}V_{o} }{(\frac{3f}{2}+2 )(P_{o}V_{o})}[/tex]

  [tex]=\frac{1}{(\frac{3f}{2}+2 )}[/tex]

For monoatomic gas [tex]f=3[/tex]

η[tex]=\frac{2}{13}[/tex]

  [tex]=0.15[/tex]

HELP ME ASAP PLEASE

I need the answers I’m in a hurry

Answers

Answer: First box----Hail

             Second Box-------Snow

             Thrid Box-------Sleet

              Forth Box-----Rain

Hope that helped! :)

Carbon dioxide had how many nonbonding electron pairs in its electron arrangement?

A. 2
B. 4
C. 8
D. 6
E. 3

Answers

Answer: A.) 2 is the answer.

Explanation:

Which best explains the relationship between evaporation and temperature?
• A liquid evaporates slower at lower temperatures because the molecules are more spread apart and are not pushed
as easily from the liquid's surface.
O A liquid evaporates faster at lower temperatures becaus the attractions are decreased and more particles can
escape the surface of the liquid.
© A liquid evaporates slower at higher temperatures because the vapor pressure of the liquid is higher, SO fewer
molecules can escape the surface.
• A liquid evaporates faster at higher temperatures because more particles have a higher speed and can overcome
attractions in the liquid.

Answers

Answer: D

Explanation:

liquid evaporates faster at higher temperatures because more particles have a higher speed and can overcome attractions in the liquid.

Answer:

D. A liquid evaporates faster at higher temperatures because more particles have a higher speed and can overcome attractions in the liquid.

Explanation:

Correct on Edge 2022!!!

Good luck everyone, you got this! Have a great day!

is a glow stick Endothermic or exothermic ?

Answers

Answer:

exothermic

Explanation:

An empirical formula calculation gives a molar ratio of 1.0 oxygen, 4.8 hydrogen, 4.1 carbon and 1.8 nitrogen. If the molecular mass is approximately 200 amu, what is the molecular formula

Answers

Answer:

[tex]C_8H_{10}O_2N_4[/tex]

Explanation:

Hello there!

In this case, according to the given information about the empirical formula of this compound, we can infer that these mole ratios can be rounded to the following whole numbers in order to find the empirical formula:

[tex]C_4H_5ON_2[/tex]

Whose molar mass is 97.09 amu and thus, the ratio of the molecular to the empirical molar mass is:

[tex]200/97.09=2.1[/tex]

Which is almost a factor of 2; and therefore, the resulting molecular formula is:

[tex]C_8H_{10}O_2N_4[/tex]

Regards!

If 15L of neon is at 25C is allowed to expand to 45L. What is the new temperature to maintain constant pressure?

Answers

Answer:

[tex]T_2=894.45K=621.30\°C[/tex]

Explanation:

Hell there!

In this case, according to the given information, it turns out possible for us to calculate the new temperature by applying the Charles' law as a directly proportional relationship between temperature and volume:

[tex]\frac{V_2}{T_2} =\frac{V_1}{T_1}[/tex]

Thus, we solve for the final temperature, T2, as shown below (make sure T1 is in Kelvins):

[tex]T_2=\frac{V_2T_1}{V_1} \\\\T_2=\frac{(25+273.15)K*45L}{15L}\\\\T_2=894.45K=621.30\°C[/tex]

Regards!

You dissolve 14 g of [tex]Mg(NO_{3} )_{2}[/tex] in water and dilute to 750 mL. What is the molarity of this solution?



Show your work

Answers

I didn’t get the answer

Qualitatively explain the effect of changing concentration of Cu2+ on voltage using your experimental observations and the Keq values below. (No calculations are required).
(a) Cu^2+(aq) + 4NH3(aq) ⇄ [Cu(NH^3)4]^2+(aq) Keq = 1.2 x 10^12
(b) CuS(s) ⇄ Cu^2+(aq) + S^2-(aq) , Keq = 8.5 x 10^-45
Cu/Zn = 0.525 V
after 1 drop NH3: 0.505 V
after 2 drops NH3: 0.435 V
Cu/Zn = 0.510 V
after 1 drop Na2S: 0.452 V
after 2 drops Na2S: 0.393 V

Answers

its the second one hope this helps

Questions
Determine the primary and secondary valencies of the following complexes and calculate their spin only magnetic
moment.
iii. [Cu(OH2)6]504
i. K[TI(CN).]
ii. [V(NH3)4Br2]
iv. K3 [Cr(CN)6]​

Answers

Answer:

yes

Explanation:

yes

Name the following alkene:
CH3CH = CHCH2CH3
A. 3-pentane
B. 2-pentene
C. 2-pentane
D. 3-pentene

Answers

Answer:

2-pentene

Explanation:

The name of the alkene is 2 pentene. The correct option is B, 2-pentene.

What is 2-pentene?

Alkenes with the chemical formula [tex]C_5H_10[/tex] are known as pentene. Within its molecular structure, each has one double bond.

The given alkene [tex]CH_3CH = CHCH_2CH_3[/tex] is 2-pentene because the double bond is present in the second carbon and it's pentene because there are five carbons present.

Thus, the correct option is B. 2-pentene.

Learn more about 2-pentene

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why does a plant have a cell wall and a cell membrane?
ASAP Pls have to turn it in at 11:00pm​

Answers

Answer:

The cell wall surrounds the plasma membrane and provides the cell tensile strength and protection. ... The cell wall surrounds the plasma membrane of plant cells and provides tensile strength and protection against mechanical and osmotic stress.

hope It Helps U

Please Mark me As brainlist

What piece of apparatus could be used to measure the volume of gas produced in a reaction
1)beaker
2)gas syringe
3) top pan balance

Answers

Answer: 2)gas syringe

Explanation:

the volume of a gas is usually measured with a gas syringe (or sometimes with an upside-down measuring cylinder)

Answer:

top pan balance

Explanation:

How many molecules of sodium fluoride (NaF) are found in 7.2 moles of sodium fluoride?

Answers

Answer:

well please answer me it's question too after you get it

Explanation:

i am also stucked in that question

No. of molecules of any substance is one mole

= Avogadro's Number = (6.022 x 10^23)

So, no. of molecules in 7.2 moles of sodium fluoride

= 7.2 × (6.022 x 10^23)

= 4.33584^24

sodium is an inactive metal why​

Answers

Answer:

Inactive metals are inert metals that doesn’t react with most of the chemicals.They are highly resistant to oxidation and corrosion when exposed to moisture.

Explanation:

Astronauts must be protected from extreme heat while
reentering the Earth's atmosphere. Scientists can use the
engineering design process to help make reentry safer.
You have defined the problem as a need for heat shields to be stronger. What
should be your next step in using the engineering design process to solve the
problem?
O A. Communicate your solution to your team members.
O B. Update your initial design for the heat shield.
O C. Identify the criteria and constraints of the project.
O D. Build a prototype of a possible new type of heat shield.​

Answers

The next engineering step to be taken is to update your initial design for the heat shield.

What is a heat sheild?

The term heat sheild refers to a device that can be used to shield an from astronaut  extreme heat especially as they re-enter the earth's atmosphere.

After you have identified the problem, the next engineering step to be taken is to update your initial design for the heat shield.

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an erlenmeyer flask contains 15.00mL of 0.030 M HCI before titration. 5.00 mL of 0.050 of M NaOH is added to the HCI in the flask during titration. What is the mole ratio of acid (HCI) to base (NaOH) in the balanced neutralization equation?
0.05 to 0.03
1:1
1:2

which expression. gives the actual moles of base added?
0.050x5.00
0.030x0.015
0.050x0.005

How many moles of H+ will be present following neautralization?
0.25
0.00025
0.025​

Answers

Answer:

1.1

0.050*0.005

0.00025

Explanation:

True or false: A skeleton equation in chemistry shows the relative amounts of all materials in the reaction

Answers

Answer:

false im pretty sure.

If it takes 720. mL of 0.00125 M Mg(OH)2 to neutralize 425 mL of an HCI
solution, what is the concentration of the HCI? Mg(OH)2 + HCl →MgCl2
+ H20

Answers

Answer:

0.004235 M

Explanation:

The neutralization reaction of this question is given as follows:

Mg(OH)2 + 2HCl → MgCl2 + 2H2O

Using the formula below:

CaVa/CbVb = na/nb

Where;

Ca = concentration of acid (M)

Cb = concentration of base (M)

Va = volume of acid (mL)

Vb = volume of base (mL)

na = number of moles of acid = 2

nb = number of moles of base = 1

From the information provided in this question;

Ca = ?

Cb = 0.00125 M

Va = 425 mL

Vb = 720 mL

na (HCl) = 2

nb = (Mg(OH)2) = 1

Using the formula; CaVa/CbVb = na/nb

Ca × 425/0.00125 × 720 = 2/1

425Ca/0.9 = 2

472.2Ca = 2

Ca = 2/472.2

Ca = 0.004235 M

The compound AlP (aluminum phosphide) is a compound semiconductor having mixed ionic and covalent bonding. Calculate the fraction of bonding that is ionic.

Answers

Answer:

0.086

Explanation:

The formula for calculating the fraction of a covalent bond can be expressed as:

= exp (-0.25ΔE²)

[tex]= exp[-0.25(E_{Al}-E_{p})^2]---(1)[/tex]

from the equation above;

[tex]E_{Al}[/tex] = the electronegativity of aluminum

[tex]E_P[/tex] = electronegativity of phosphorus

Using the data from periodic table figures;

[tex]E_{Al}[/tex] = 1.5

[tex]E_P[/tex] = 2.1

fraction of the covalent = exp[-0.25(1.5 - 2.1)²]

fraction of the covalent = exp(-0.09)

fraction of the covalent = 0.914

Now, the fraction of ionic bond will be = 1 - the fraction  of covalent bond

= 1 - 0.914

the fraction of bond that is ionic = 0.086

What happens when an electron moves to a higher energy level?
A. It releases energy of a specific frequency
B. It gains energy in a quantized amount.
C. It loses energy in the form of light.
D. It absorbs photons of many energies

ANSWER: B. It gains energy in a quantized amount. ​

Answers

Answer:

B. It gains energy in a quantized amount. ​

Rachard is studying a sample of a substance. The sample is in a large, triangle-shaped flask. Rachard moves the sample to a small, rectangular container. Both containers are closed. Below is an image of the containers used by Rachard. She notices that the shape and the volume of the substance both change when the sample is moved. In which state of matter is the substance?

Answers

There’s no image for me to look at.

How many neutrons are in an atom of argon–40?

Answers

Answer:

22 neutrons

Explanation:

If so please sorry

When a balloon containing 635 mL of air is taken from sea level (at standard pressure) to a higher altitude, the balloon expands to 829 mL. What is the air pressure at this new altitude (in atm)?

Answers

Answer:

0.766atm

Explanation:

Boyles law

P1V1=P2V2

1×635=P2×829

P2=635/829

P2=0.766atm

Calculate the percent composition of Ca3P2

Answers

Calculate the molar mass of Ca3P2 in grams per mole or search for a chemical formula or substance.

Answer:

Ca - 66%, P - 34%

Explanation:

So, this is the formula we can use to find the amount of each element:

Element count * Atomic mass = Mass

Plug in our elements for this:

Ca - 3*40.078=120.234

P - 2*30.973=61.946

Now, to find the percentage of mass, we must find total mass, and divide the two elements mass count by this total mass:

120.234+61.946=182.18

Now divide each element mass by the total mass:

Ca - 120.234/182.18=0.6599(Round to 0.65)

P - 61.946/182.18=0.34002(Round to 0.34)

Then multiply both numbers by 100 to get the percentage:

Ca - 65%

P - 34%

So these our your two answer!

Hope this helps!

What happens in radioactive decay?
O A. An electron is lost to form a negatively charged particle.
O B. An unstable nucleus breaks down into smaller parts.
O C. Two smaller nuclei are joined to form one larger nucleus.
O D. A large nucleus breaks apart to form smaller nuclei.
SHIRME

Answers

A radioactive atom will spontaneously release radiation in the shape of energy rather than particles in order to transition into a more steady state.

Why is something radioactive?

Radioactivity, as its name suggests, seems to be the act of generating radiation without any external cause. This is carried out by an unstable atomic nucleus that "wants" to abandon certain power in order to change to a more stable form.

Are people radioactive at all?

Absolutely, since humans consume radioactive materials from the environment through food, drink, and air, our bodies are inherently radioactive. Our bodies take these substances in and store them in our bones, tissues, and organs. We also breathe them in and consume them.

To know more about radioactive visit:

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