what is the standard enthalpy of combustion of ethane? (b) what is the specifi c enthalpy of combustion of ethane? (c) is ethane a more or less effi cient fuel than methane?

Metal of the following surfaces does NOT absorb moisture.

The correct option is B.

The presence of a liquid, things like water, even in minute amounts, is referred to as moisture. Examples of locations where small amounts of water can be found include the air (humidity), foods, and some commercial goods. The amount of water vapor in the atmosphere is also alluded to as moisture.

Warm, moist weather that comes in touch with a cool surface, such uninsulated cold water mains, causes moisture to condense into water droplets. Numerous other represent the lowest including cooking, taking a bath, drying clothing, washing the dishes, and others also release moisture into the air.

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The complete question is -

Which of the following surfaces does NOT absorb moisture? *

A-Cardboard

B- Metal

C-Magazine cover

D-Rough wood

Answer:

The reactants of photosynthesis are carbon dioxide and water.

By using the expression for the equilibrium constant for the reaction and solving the appropriate quadratic equation, we can calculate that the equilibrium concentration of iodine will be 1.77 M.

The balanced reaction equation for this reaction looks like this:

[tex]2 IBr[/tex] → [tex]I_{2}+Br_{2}[/tex]

The expression for the equilibrium constant will look like this:

[tex]K_{c} =\frac{[I_{2} ][Br_{2} ]}{[IBr]^{2} }[/tex]

Because all the volumes are the same, we can just use the moles of all reaction components instead of concentrations. Now, because there was no iodine or bromine when the reaction began, all iodine and bromine present at equilibrium are formed by IBr decomposition, their concentrations will be the same (X). The concentration of IBr will be reduced by 2X, so we can plug that into the equilibrium constant expression:

[tex]8.5=\frac{X^{2} }{(4.14-2X)^{2} }[/tex]

We transform this expression to get a quadratic equation:

33X² - 140.76X + 145.6866 = 0

When we solve for X, one solution is 2.49 M (which is impossible, because 4.14 moles of IBr can create a maximum of 4.14 mol / 2 = 2.07 mol of iodine), and the other (correct) solution is 1.77 M.

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The volume of the substance with mass of 54mg and density of 1.2g/mL will be 0.045 mL.

How much "stuff" is contained in a specific quantity of space is determined by its density. For instance, a block of the harder, lighter element gold (Au) will be denser than a block of the heavier element lead (Pb) (Au). Styrofoam blocks are less dense than bricks.

Mass per unit volume serves as its definition.

We know that, Density = mass of substance / volume of substance

Given,

mass = 54 mg = 0.054 g

Density = 1.2g/mL

D = m/ v

1.2 = 0.054 / v

1.2 × v = 0.054

v = 0.054 / 1.2

v = 0.045 mL

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The volume  of each of the following bases will react completely with 23.00 mL of 0.500 M HCl are given below ,

( a ) 28 ml

( b ) 230 ml

( c ) 46 ml

The volume  of each of the following bases will react completely with 23.00 mL of 0.500 M HCl can be calculated as ,

Formula used : [tex]M_{1} V_{1}[/tex] =  [tex]M_{2} V_{2}[/tex]               ( 1 )

( a )

Given

[tex]M_{1}[/tex] = 0.500 M

[tex]M_{2}[/tex] = 0.100 M

[tex]V_{1}[/tex] = 23.00 mL

[tex]V_{2}[/tex] = ?

Now putting the all given data in equation ( 1 ) we get the value of volume

0.500 M × 23.00 mL = 0.100 M ×  [tex]V_{2}[/tex]

[tex]V_{2}[/tex] = 0.500 M × 23.00 mL / 0.100 M = 28 ml

( b )

Given

[tex]M_{1}[/tex] = 0.500 M

[tex]M_{2}[/tex] = 0.0500 M

[tex]V_{1}[/tex] = 23.00 mL

[tex]V_{2}[/tex] = ?

Now putting the all given data in equation ( 1 ) we get the value of volume

0.500 M × 23.00 mL =0.0500 M  ×  [tex]V_{2}[/tex]

[tex]V_{2}[/tex] = 0.500 M × 23.00 mL / 0.0500  M = 230 ml

( b )

Given

[tex]M_{1}[/tex] = 0.500 M

[tex]M_{2}[/tex] = 0.250 M

[tex]V_{1}[/tex] = 23.00 mL

[tex]V_{2}[/tex] = ?

Now putting the all given data in equation ( 1 ) we get the value of volume

0.500 M × 23.00 mL = 0.250 M  ×  [tex]V_{2}[/tex]

[tex]V_{2}[/tex] = 0.500 M × 23.00 mL / 0.250 M = 46 ml

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For polar molecules :

a) The polarities of the bonds must not cancel each other out  is True.

b) All of the bonds must be polar is false. if we have one polar bond the molecule is polar.

c) there must be at least one nonbonding pair of electrons is false.

d) the molecule must be symmetrical is False.

e) double or triple bonds do not count is false

f) all of the bonds must be nonpolar is false.

g) all of the terminal atoms around a central atom must have different identities is False.

h) at least one bond must be polar is true.

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If a compound rotates plane-polarized light in a clockwise direction, the compound is called dextrorotatory, and is labeled d

If a compound rotates plane-polarized light in a anti- clockwise direction, the compound is called levorotatory compound is labeled as l.

An enantiomers rotate the plane polarized light in clockwise direction or positive direction is called dextrorotatory. given as [(+), d- ]. while enantiomers that rotates plane polarized light in anti - clock wise direction or negative direction is called levorotatory compound . given as [ (-) , l-].

Thus, If a compound rotates plane-polarized light in a clockwise direction, the compound is called dextrorotatory, and is labeled d

If a compound rotates plane-polarized light in a anti- clockwise direction, the compound is called levorotatory compound is labeled as l.

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Strong and Weak Foundations Bases provide a similar problem: a strong base is one that is completely ionized in solution.

Strong and Weak Foundations Bases provide a similar problem: a strong base is one that is completely ionized in solution. A weak base is one that is less than 100% ionized in solution.

Acids and bases are incompatible. Acids and bases will balance one another out. A solution's pH can be changed by acids but not by bases. While bases give hydrogen ions (H+), acids give hydroxide ions (OH-).

The aqueous solution of the salt formed by neutralisation of weak acid and strong base possesses basic nature, while aqueous solution of salt produced by neutralisation of weak base and strong acid possesses acidic nature.

The complete question is:

A strong base or salt in solution exist predominately as electrons in solution.

a) True

b) False

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Answer:

that "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules." For a given mass of an ideal gas, the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are constant.

1.28atm

According to Boyle's law

P1V1 = P2V2

where

P is the pressure

V is the volume

Given the following

P1 = 2atm

V1 = 3.2L

V2 = 5L

Required

Final pressure P2

Substitute

P2 = P1V1/V2

P2 = 2*3.2/5

P2 = 6.4/5

P2 = 1.28atm

Hence the pressure in atm of the expanded gas sample

The order of synthetic cycle for generation of fatty acid is Condensation > Reduction > Dehydration > Reduction.

What is fatty acid?

An aliphatic carboxylic acid with a saturated or unsaturated chain is referred to as a fatty acid and is employed in chemistry, particularly in biochemistry. In some species, like microalgae, fatty acids make up a significant portion of the lipids (up to 70% of the total weight). However, in some other creatures, such as triglycerides, phospholipids, and cholesteryl esters, fatty acids are not found in their freestanding form. In all of these forms, fatty acids are essential nutritional sources of energy for animals and essential cellular building components.

The synthetic synthetic cycle for the generation of fatty acids takes place in such a way that at first Condensation happens then Reduction then Dehydration then again Reduction happens.

The cycle of condensation, reduction, dehydration, and reduction continues until palmitoyl‐ACP gets completely made.

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Answer: Making elephant toothpaste, roasting a marshmallow, And burning a piece of paper are all examples of chemical changes.

Explanation:

A chemical change is when the atoms in something have broken old bonds and made new ones.

Making elephant toothpaste is NOT a physical change because two things are mixed together to make a chemical change and therefore it's a chemical change not a physical change.

Burning a piece of paper is not a physical change because when a paper is burned it turns into ash/dust and it changes its chemical composition. Therefore it's a chemical change, not a physical one

A pressure of 210.5 torr will be exerted by the gas if the temperature is raised to 43.1°C.

According to Charles's law P₁/T₁ = P₂/T₂

Given,  P₁ is 127 torr and T₁ is 26°C and T₂ is 43.1°C.

127/ 26 = P₂/ 43.1

P₂ = (127 × 43.1) / 26

P₂ = 5473.7 / 26

P₂ = 210.5 torr

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The student made a mistake in substituting the wrong values of the relative abundance of the isotopes Potassium-39 and Potassium-41. That is why his answer was wrong.

The student exchanged the values of the relative abundance of the isotope values. That is why it has resulted in the wrong value of the average atomic mass. On substituting the correct values using the following formula, we get the atomic mass of the respective isotopes as,

atomic mass = Mass x Relative abundance

atomic mass of K⁴¹₁₉ = 40.962 x 0.0688

the atomic mass of K⁴¹₁₉ = 2.8181856amu

Similarly, for the mass of K₃₉¹⁹ = 38.964 x 0.9312

                                                  = 36.28327amu

Thus the average atomic mass of Potassium is given by,

Average atomic mass of potassium = Mass of K₃₉¹⁹ + Mass of K⁴¹₁₉

The average atomic mass of potassium = 36.2832 +2.8181

The average atomic mass of potassium = 40.962amu

Hence, the correct value of the average atomic mass is thus obtained.

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Answer:

Arrhenius defined an acid as a compound that increases the concentration of hydrogen ion (H +) in aqueous solution. Many acids are simple compounds that release a hydrogen cation into solution when they dissolve.

Answer:

Oxytocin is a peptide of nine amino acids (a nonapeptide). 

Explanation:

Answer:Oxytocin is a peptide of nine amino acids (a nonapeptide). The sequence is cysteine - tyrosine - isoleucine - glutamine - asparagine - cysteine - proline - leucine - glycine (CYIQNCPLG).

Explanation:

The arrangement of an atom's or molecule's electrons in atomic or molecular orbitals is known as the electron configuration in atomic physics and quantum chemistry.

One orbital can house a maximum of two electrons, and there are four different types of orbitals (s, p, d, and f). More electrons can be held in the p, d, and f orbitals since they contain various sublevels. Each element's position on the periodic table determines the specific electron configuration of that element. The arrangement of an atom's or molecule's electrons in atomic or molecular orbitals is known as the electron configuration in atomic physics and quantum chemistry.

A standardized notation is used for expressing electron configurations, in which the energy level and type of orbital are written first, followed by the number of electrons in the orbital, which is expressed in superscript. For instance, carbon's (atomic number: 6) electronic configuration is 1s22s22p2.

Hence. The elements are denoted by the  electron configurations are,

1) Beryllium

2) Boron

3) Magnesium

4) Silicon

5) Phosphorus

6) Calcium

7) Nickel

8) Krypton

9) Bromine

10) Strontium

The complete question is,

Determine the elements denoted by the following electron configurations.​

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As you climb to the top of a academic mountain in florida, air pressure decreases from 1 atm to0.75 atm at the peak. what will the partial pressure of oxygen be at the top of the mountain.

Pressure

Pressure( symbol p or P) is the force applied vertical to the face of an object per unit area over which that force is distributed.

Colorful units are used to express pressure. Some of these decide from a unit of force divided by a unit of area; the SI unit of pressure, the pascal( Pa), for illustration, is one newton per forecourt metre( N/ m2); also, the pound- force per forecourt inch( psi) is the traditional unit of pressure in the Homeric and U.S. customary systems. Pressure may also be expressed in terms of standard atmospheric pressure; the atmosphere( atm) is equal to this pressure, and the torr is defined as 1⁄760 of this. Manometric units similar as the centimeter of water, millimeter of mercury, and inch of mercury are used to express pressures in terms of the height of column of a particular fluid in a manometer.

Pressure is the quantum of force applied vertical to the face of an object per unit area. The symbol for it's" p" or P.( 2) The IUPAC recommendation for pressure is a lower- case p.( 3) still, upper- case P is extensively used. The operation of P vs p depends upon the field in which one is working, on the near presence of other symbols for amounts similar as power and instigation, and on writing style.

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Answer:

2 - B, 5 - D, 6 - A

Explanation:

2 - Penicilin was actually discovered on accident!

5 - Microbes were discovered around the mid-1600s

6 - Choice A seems to be correct here, noting that the answers of C and D are marked out and B seems a bit far-fetched (from my current knowledge)

The annual operation of the refrigerator produces 6835.5 g of sulfuric acid. This calculation is made assuming that the enthalpy of combustion for sulfur is equal to the enthalpy of combustion for carbon.

First, we are going to transform 655 kWh into kilojoules. Because 1 kWh = 3.6e6 J = 3600 kJ, that means that a typical frostless refrigerator uses 655 * 3600 kJ = 2358000 kJ of energy on a yearly basis.

The enthalpy of combustion for carbon (or enthalpy of carbon dioxide formation) is -393 kJ/mol. That means that we can calculate the number of moles of carbon needed to produce 2358000 kJ of energy.

2358000 kJ / 393 kJ/mol = 6000 mol of carbon

Because the molar mass of carbon is 12 g/mol we need

6000 mol * 12 g/mol = 72000 g of carbon

If 3.1% of this carbon is actually sulfur, then we will burn 0.031 * 72000 g = 2232 g of sulfur during one year. The molar mass of sulfur is 32 g/mol, which means we transformed 2232 g / 32 g/mol = 69.75 mol of sulfur into sulfur dioxide and further into sulfuric acid. Because 1 mol of sulfur is needed to produce 1 mol of sulfuric acid, we produced 69.75 moles of sulfuric acid.

The molar mass of sulfuric acid is 98 g/mol, so over the course of one year, we produced 69.75 mol * 98 g/mol = 6835.5 g of sulfuric acid.

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The control provides a reference value for comparison to samples in which a variable is changed.

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Answer:

The element copper has naturally occurring isotopes with mass numbers of 63 and 65. The relative abundance and atomic masses are 69.2% for mass = 62.93 amu, and 30.8% for mass = 64.93 amu.

Volume of the helium in weather balloon at 15 °C with initial volume of 10L and temperature of 5 °C is 30 L

Given that, Initial volume (V1) = 10 L

Initial Temperature (T1) = 5 °C

Final Temperature (T2) = 15 °C

By gas law,

V1 / V2 = T1 / T2 (Pressure constant)

10 / V2 = 5 / 15

V2 = (15 / 5) * 10

V2 = 3 * 10

V2 = 30 L

Thus, the volume of helium in the weather balloon at 15 °C is 30 L

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Answer:

120/0.5

=240ohms

B. the specific heat of water

A multicellular organism is an organism that consists of many cells. The term "multi" is technically used to refer to something that is more than one, so "multicellular" means more than one.

Multicellular organisms evolve through cell specialization and division of labour. Cells become efficient at one process and depend on other cells to carry out different processes. All the cells work in coordination to ensure the proper functioning of the body.

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By utilizing ideal gas laws and the conversion of given temperatures into absolute temperatures we can calculate that the pressure of the gas at 89 °C will be 2.59 atm.

Amonton's law (one of ideal gas laws) states that at constant volume and number of moles of the ideal gas, the pressure that the gas exerts is directly proportional to the temperature of the gas. In mathematical form:

[tex]\frac{P_{1} }{T_{1} } = \frac{P_{2} }{T_{2} }[/tex]

P is the pressure of the gas while T is absolute temperature (in Kelvins). First, we convert temperature in Celsius to Kelvins:

T1 = (21 + 273) K = 294 K

T2 = (89 + 273) K = 362 K

Now, we transform the Amonton's law equation so that we can calculate the pressure at the higher temperature:

P2 = T2 * P1 / T1

Finally, we plug the known values into the transformed equation:

P2 = 362 K * 2.10 atm / 294 K = 2.59 atm

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In areaction, the number of moles consumed and produced have the same ratio as the coefficients on the balanced equation.

So, to calculate the number of moles of any chemical on the reaction given the number of moles of any other, we can use a rule of three.

We put the compound or atom we want on the first column and the one we have information of on the second, and their coefficients on the second row:

We want Al and we have information about Al₂O₃, and their coefficients on the balanced equation are 4 and 2, so:

Al --- Al₂O₃

4 2

Now, we use thise placements to write the equation:

Where the n stands for the number of moles. Now we solve for Al:

And since we know the number of moles of Al₂O₃, we have:

Where the last step we did an approximateion to get to 3 significant figures.

So, the number of moles of Al consumed is 1.60 mol.

Answer:

b Atom X = 1; Atom Y = 7

Explanation:

a valence electron is an electron in the outer shell

So X has 1 in outer shell

Y has 7 in outer shell