there are 25 elements found in living things. how many of these elements are found in some organisms but not at all?

The molecules in a gas move faster than in a liquid.

Answer:

D. [tex]K_{a} = \frac{[\text{H}^{+}][\text{NO}_{2}^{-}]}{[\text{HNO}_{2}]}[/tex]

Explanation:

The general form of an equilibrium constant expression is

[tex]K = \frac{[\text{Products}]}{[\text{Reactants}]}[/tex]

In the equilibrium

HNO₂ ⇌ H⁺ + NO₂⁻

The products are H⁺ and NO₂⁻, and the reactant is HNO₂.

∴ [tex]K_{a} = \frac{[\text{H}^{+}][\text{NO}_{2}^{-}]}{[\text{HNO}_{2}]}[/tex]

Answer:

The correct answers are (1) True (2) London dispersion force (3) one of the option is missing, none of these three is an answer (4) The total number of electrons increases down the group, and this increases the strength of the intermolecular forces (5) London dispersion forces which are always present.

Explanation:

Given: An instantaneous dipole occurs when a molecule's moving electrons are briefly more concentrated in one place than another, causing the molecule to become temporarily polarized.

Answer: True

when the electrons moving in a molecule or an atom move towards one end of the molecule or atom the other end has a small positive pole at that time and the end where electrons move has a small negative pole. So, a dipole is formed for that instant.

(2) What type of intermolecular force occurs between all substances?

Answer: London dispersion force

remember from first part how an instantaneous dipole is formed. When a pole is formed at that instant the molecule in neighborhood can interact with the dipole that was formed. The dipole that was formed has a positive pole and a negative pole. If the neighboring molecule is present near positive pole it’s electrons will get attracted to the positive pole of the dipole. This interaction is called London dispersion force. Since every atom or molecule or ion in the universe has electrons, so there is development of instantaneous dipole in each of them and each one of them has London dispersion force acting on them.

(3) When comparing [tex]H_2,\;NH_3,\;O_2,\; \rm{and}\;{CH_4[/tex] which of the following statements is correct?

Answer: one of the option is missing, none of these three is an answer.

(4)The boiling points of diatomic halogens are compared in the table.

Answer: The total number of electrons increases down the group, and this increases the strength of the intermolecular forces.

(5) What is the strongest intermolecular force that occurs between molecules of [tex]CO_2[/tex]?

Answer: London dispersion forces which are always present.

London forces are weakest forces, if other forces would have been present then we would have ignored London forces but since no other forces are present, the only choice is London forces.

[tex]CO_2[/tex] is a non polar molecule, it does not have permanent dipole moment. So there are no chances of dipole-dipole, [tex]CO_2[/tex] doesn’t have a positive or negative charge so even not ionic bond.

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The Answer is: 1.86×10^4

Answer:

1.86 x 104

Explanation:

This mathematical operation is a multiplication, so:

1.- Multiply the number as usual: 6 x 3.1 = 18.6

2.- Multiply the coefficients, remember since they coefficients, a multiplication, actually you need to add them: 4 + (-1) = 3+

3.- Then you write the number with the coefficient: 18.6 x 103

4.- In this case since the scientific notation just admit one number will be:

1.86 x 104

A. repeat the investigation several times. You must repeat an experiment to make sure it is valid.

Answer:

the answer is A

Explanation:

Explanation: For evaluating the combined gas law, we use four laws:

Charles' Law: Volume of a gas is directly proportional to the Temperature at Constant Pressure.

                           [tex]V\propto T[/tex]      (at constant Pressure)

Boyle's Law: Volume of a gas is inversely proportional to the Pressure of a gas at constant Temperature.

                           [tex]V\propto \frac{1}{P}[/tex]   (at constant Temperature)

Gay-Lussac's Law: Pressure of the gas is directly proportional to the Temperature at constant Volume.                                                                  

                           [tex]P\propto T[/tex]      (at constant Volume)

Avogadro's Law: Volume of gas is directly proportional to the number of moles of gas at constant Pressure and constant Temperature.

                          [tex]V\propto n[/tex]      (at constant Pressure and Temperature)

Combining all the four laws, we get

                           [tex]PV\propto nT[/tex]

                            PV=nRT     (Combined Gas Law)

where, R = Gas constant

Now, we need to calculate the pressure, rearranging the terms:

                          [tex]P=\frac{nRT}{V}[/tex]

When an ideal gas at Initial Pressure [tex]P_1[/tex], Volume [tex]V_1[/tex] and Temperature [tex]T_1[/tex] undergoes change in variables to Final pressure [tex]P_2[/tex], Volume [tex]V_2[/tex] and Temperature [tex]T_2[/tex] , we write

                         [tex]\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]

                        [tex]P_2=(\frac{P_1V_1}{T_1})(\frac{T_2}{V_2})[/tex]

Answer : The variables in the numerator (a) will be, [tex]P_1,V_1,T_2[/tex] and the variables in the denominator (b) will be, [tex]V_2,T_1[/tex]

Explanation :

The combined gas law has arrived from the combination of the four laws:

1) Boyle's Law : It is defined as the pressure of the gas is inversely proportional to the volume of the gas at constant temperature and the number of moles.

[tex]P\propto \frac{1}{V}[/tex]

2) Charles' Law : It is defined as the volume of the gas is directly proportional to the temperature of the gas at constant pressure and number of moles.

[tex]V\propto T[/tex]

3) Gay-Lussac's Law : It is defined as the pressure of the gas is directly proportional to the temperature of the gas at constant volume and number of moles.

[tex]P\propto T[/tex]

4) Avogadro's Law : It is defined as the volume of the gas is directly proportional to the number of moles of the gas at constant pressure and temperature.

[tex]V\propto n[/tex]

By combining these four laws, we get the combined gas law.

[tex]PV\propto nT\\\\PV=nRT[/tex]

where, R = gas constant

An ideal gas at initial pressure [tex]P_1[/tex], initial volume [tex]V_1[/tex] and initial temperature [tex]T_1[/tex] undergoes changes with the variables to final pressure [tex]P_2[/tex], final volume [tex]V_2[/tex] and final temperature [tex]T_2[/tex].

By rearranging the gas law, we get the final pressure.

[tex]\frac{P_1V_1}{P_2V_2}=\frac{T_1}{T_2}\\\\P_2=\frac{P_1V_1T_2}{V_2T_1}[/tex]

Therefore, the variables in the numerator (a) will be, [tex]P_1,V_1,T_2[/tex] and the variables in the denominator (b) will be, [tex]V_2,T_1[/tex]

Hello!

To find the number of moles in the given amount of aluminum, we need to know the mass of one mole of aluminum, and divide that by the given amount of aluminum.

One mole of aluminum is equal to about 27 grams. With that, we can divide it by the given amount of aluminum.

198.5 grams / 27 grams ≈ 7.35185185

According the number of significant figures, there are about 7.4 moles of aluminum in 189.5 grams of aluminum.

Yes, it is possible to combine the same two elements to form two different compounds. An example is carbon dioxide CO2 and carbon monoxide CO. This is because two elements can form different types of bond and end up with different compounds.

There is a limited number of elements but a large number of compounds because of the above reason.

Yes, two different compounds can be made from the same two elements by altering their atomic ratios. Despite having fewer than 120 elements, innumerable compounds exist due to various ways elements can combine and bond.

A. This is because different compounds can be created by changing the ratio of atoms of each element. For instance, depending on the number of oxygen atoms bonded to each carbon atom, carbon and oxygen can combine to form carbon monoxide (CO) or carbon dioxide (CO₂).

B. The reason for this is that elements can combine in a variety of ways, resulting in a wide range of compounds with distinct properties. For example, even if two elements form a compound in the same ratio, they can combine in different ratios to form entirely different compounds.

Factors influencing compound formation

The correct answer is option (B) [Ne]3s¹3p⁶.

The electron configuration of Cl is [Ne]3s²3p⁵ in the ground state.

The electron configuration of Cl is [Ne]3s¹3p⁶ in the excited state.

In the excited state one electron from the 2s orbital jumps to the 2p orbital. As a result the 2p orbital becomes completely filled with 6 electrons and the 2s orbital is partially filled with only 1 electron. To be completely filled a p and a s orbital can have a maximum of 6 and 2 electrons respectively.

Thus [Ne]3s¹3p⁶ electron configuration correspond to an atom with an electron in an excited state.

Answer: Option (A) is true.

Explanation:

In a laboratory, the solutions are prepared in advance so that as and when the need arises they can be easily available. As these solutions are prepared by keeping in mind the correct ratio of concentrations.

Hence, when a person need to fill a test tube with hydrochloric acid then he/she just need to find the bottle of acid and pour the contents into the test tube.

Thus, it can be conclude that the statement is true.

Answer: True

Explanation:

In a laboratory if someone needs a test tube full of hydrochloric acid then it should be directly poured into the test tube.

As required in the experiment or during the experiment, the hydrochloric acid is pored and used in the experiment.

During the time of experiment the concentration of HCl can be adjusted base on the type of experiment.

So, it is true that hydrochloric acid can be poured directly in the test tube from the bottle.

to be as exact as i can it is all of them they all work together to make water good.

When multiplying 2.3 mm by 8.00 mm to find area, how should you report your answer?

A. 18 mm^2

Chemical properties include characteristics that describe how a substance changes its chemical structure or composition, as in the case of flammability. The correct answer is c) Include changes that alter the identity of a substance, because chemical properties lead to chemical changes, which result in new substances with different identities.

The chemical properties of a substance refer to the characteristics that describe its ability to undergo specific chemical changes that alter its identity. For instance, the flammability of a substance is a chemical property because when a substance burns, it produces new substances with different chemical compositions. Observing a chemical property involves causing a chemical change.

a) Can be observed without altering the identity of a substance: This statement describes a physical property, not a chemical property.

b) Include mass and color: These are examples of physical properties, not chemical properties.

c) Include changes that alter the identity of a substance: This statement correctly defines a chemical property.

d) Include changes of state of a substance: Changes of state, such as melting or freezing, are physical changes, not chemical changes.

Therefore, the correct answer is c) Include changes that alter the identity of a substance, because chemical properties involve changes in the chemical structure or composition of a substance, such as its reaction to form new substances.

I think the answer is B because Sound travels about 1,500 m/s underwater, and sound travels about 332 m/s in air. Sound underwater travels faster and longer in water. The particles are more tightly packed together, so sounds travel faster through water.

Hey there!:

1 mole of FeSO4 = 151.8 g/mol

25.0 g change to mole  = 25.0 / 151.8

moles of FeSO4 = 0.165 moles

One mole of any substance has  6.02*10²³ units

0.165 moles to get the number of Fe ( II ) ions :

number of  Fe(II) ion = 0.165 * ( 6.02*10²³ )

number of Fe ( II ) ion = 9.93*10²² units

Answer:

[tex]ions_{Fe^{2+}}=9.90x10^{22}ionsFe^{2+}[/tex]

Explanation:

Hello,

In this case, the following mole-mass relationship, is applied to obtain the ions of iron (II) in 25.0 g of iron (II) sulfate whose molar mass is 152 g/mol:

[tex]ions_{Fe^{2+}}=25.0gFeSO_4*\frac{1molFeSO_4}{152gFeSO_4}*\frac{1molFe^{2+}}{1molFeSO_4}*\frac{6.022x10^{23}ionsFe^{2+}}{1molFe^{2+}} \\ions_{Fe^{2+}}=9.90x10^{22}ionsFe^{2+}[/tex]

Best regards.

The balanced chemical equation for the given reaction:

NaHCO₃ + HCl --> NaCl + H₂O + CO₂

Given, mass of NaHCO₃ = 0.05 g

Molar mass of NaHCO₃ = 84.007 g/mol

Moles = mass/molar mass

Moles of NaHCO₃ = 0.05 g/84.007 g/mol

Moles of NaHCO₃ = 6.0 x 10⁻⁴

Given, mass of HCl = 0.05 g

Molar mass of HCl = 36.46 g/mol

Moles of HCl = 0.05 g/ 36.46 g/mol

Moles of HCl = 1.4 x 10⁻³

Since NaHCO3 has the least number of moles, it is the limiting reagent.

As per the balanced equation the molar ratio between NaHCO₃ : CO₂ is 1:1

Therefore, moles of CO₂ = 6.0 x 10⁻⁴

Molar mass of CO₂ = 44 g/mol

Mass = moles x molar mass

Mass of CO₂ =  6.0 x 10⁻⁴ mol x 44 g/mol = 0.0264 g

Mass of carbon dioxide gas produced = 0.0264 g

Most of these questions relate to the Doppler Effect - how the frequency of sound and light waves changes depending on whether the source is moving towards or away from the observer. Moving toward an observer leads to higher frequencies and a 'blue shift' while moving away leads to lower frequencies and a 'red shift'.

1. As an object moves towards another object the sound waves bunch up. True. This is a representation of the Doppler Effect where the frequency appears to change when a source of sound is moving relative to the observer.

2. As an object moves toward another object the sound waves have a lower frequency. False. As the object moves closer, the sound waves will have a higher frequency.

3. As an object moves toward another object the sound waves have a lower frequency. False as explained in the question.

4. Faster sources moving towards an object have a higher pitch than slower-moving sources. True. Faster moving sources will cause the sound waves to bunch up leading to higher frequency and hence greater pitch.

5. An object moving away will have a lower pitch. True. The pitch will appear to be lower as the sound waves are spread out.

6. Lower shows differences in frequency as color. This sentence is not clear enough to provide an accurate response.

7. An object moving away to be blue-shifted. False. An object moving away shows a red shift; a blue shift occurs when an object is moving toward the observer.

8. Is a star that shows as blue-shifted moving toward the observer. True. The blue shift indicates that a cosmos object is moving towards us.

9. Faster-moving objects show MORE shifts in frequency. True. The frequency of light waves will change more noticeably with faster-moving objects due to the Doppler effect.

10. Galaxies appear to be redshifted from observing on Earth. Is this because they are moving towards the earth? False. Galaxies are moving away from the Earth which is why they appear redshifted.

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Answer;

-Acceleration: 10 km/h/s east

Explanation;

-The quantity is either a vector or a scalar. Scalars are quantities that are fully described by a magnitude (or numerical value) alone while Vectors are quantities that are fully described by both a magnitude and a direction.

Acceleration is a vector quantity that is defined as the rate at which an object changes its velocity. An object is accelerating if it is changing its velocity.

In this case , a =( v-u)/t ; where a is the acceleration, v is the final velocity, u is the initial velocity and t is time.

      a = (60 - 0)/6

         = 10 km/h/s

Final answer:

In the scenario, the vector quantities are 'acceleration: 10 km/h/s east' and 'velocity: 10 km/h/s east' since they include both magnitude and a direction, unlike the scalar quantities 'speed: 60 km/h' and 'distance: 60 km', which lack direction.

Explanation:

In the provided scenario of a sports car accelerating uniformly, the quantity that represents a vector is acceleration: 10 km/h/s east and velocity: 10 km/h/s east. Both these quantities include both magnitude and direction. In contrast, 'speed: 60 km/h' is a scalar as it only specifies magnitude and does not include direction. Similarly, 'distance: 60 km' is also a scalar quantity because it states how far the car has traveled without a specific direction.

Vector quantities are defined by both magnitude and direction, which is the case with the acceleration and velocity specified 'east' in this scenario. Scalar quantities, such as speed and distance, only have magnitude without any reference to direction.

that would be 2226.109837560 sorry if i'm wrong have a nice day.

The question is incomplete, here is the complete question:

Calculate the standard enthalpy of combustion of sucrose. The standard enthalpy of formation of sucrose is -2226.1 kJ/mol

Answer: The standard enthalpy of combustion of sucrose is -5636.52 kJ

Explanation:

Combustion reaction is defined as the chemical reaction in which a hydrocarbon reacts with oxygen gas to produce carbon dioxide gas and water molecule.

[tex]\text{Hydrocarbon}+O_2\rightarrow CO_2+H_2O[/tex]

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. The equation used to calculate enthalpy change is of a reaction is:

[tex]\Delta H^o_{rxn}=\sum [n\times \Delta H_f^o_{(product)}]-\sum [n\times \Delta H_f^o_{(reactant)]}[/tex]

The chemical equation for the combustion of sucrose follows:

[tex]C_{12}H_{22}O_{11}(s)+12O_2(g)\rightarrow 12CO_2(g)+11H_2O(l)[/tex]

The equation for the enthalpy change of the above reaction is:

[tex]\Delta H^o_{rxn}=[(12\times \Delta H_f^o_{(CO_2)})+(11\times \Delta H_f^o_{(H_2O)})]-[(1\times \Delta H_f^o_{(C_{12}H_{22}O_{11})})+(12\times \Delta H_f^o_{(O_2)})][/tex]

We are given:

[tex]\Delta H_f^o_{(H_2O)}=-285.8kJ/mol\\\Delta H_f^o_{(CO_2)}=-393.51kJ/mol\\\Delta H_f^o_{(C_{12}H_{22}O_{11})}=-2226.1kJ/mol\\\Delta H_f^o_{(O_2)}=0kJ/mol[/tex]

Putting values in above equation, we get:

[tex]\Delta H^o_{rxn}=[(12\times (-393.51))+(11\times (-285.8))]-[(1\times (-2226.1))+(12\times (0))]\\\\\Delta H^o_{rxn}=-5636.52kJ[/tex]

Hence, the standard enthalpy of combustion of sucrose is -5636.52 kJ

Answer: The correct answer is Option D.

Explanation:

Weak acid is defined as the acid which does not completely dissociates into its ion when dissolved in water.

For the given options:

Option A: [tex]HCl+H_2O\rightarrow H_3O^++Cl^-[/tex]

HCl is a strong acid because it completely looses its proton when dissolved in water.

Option B: [tex]HCO_3^-+H_2O\rightarrow H_2CO_3+OH^-[/tex]

Hydrogen carbonate ion is a base because it is easily accepting a proton from water.

Option C: [tex]H_2O\rightarrow H^++OH^-[/tex]

The above equation represents the ionization of water.

Option D: [tex]HCOOH+H_2O\rightarrow H_3O^++HCOO^-[/tex]

Formic acid is considered as a weak acid because it does not completely dissociates into its ions when dissolved in water.

From the above information, the correct answer is Option D.

The answer is D. It was frozen.

This is because freezing an object doesn't change chemical properties, only change the state of the matter.

Final answer:

A protein is best described as a polymer made up of 20 or more amino acid monomers, with proteins varying greatly in size and function.

Explanation:

The correct statement that best describes a protein is (D) a polymer made up of 20 or more amino-acid monomers. Proteins are essential biomolecules within living organisms, made from building blocks known as amino acids, which are connected by peptide bonds forming long chains. There are 20 standard amino acids that can combine in various sequences to form a vast array of proteins, each with unique functions and properties. These proteins can be as small as a few dozen amino acids to several thousand in the larger proteins.

Answer:

The answer is A: the part of the earth and its atmosphere in which living organisms exist or that is capable of supporting life.

Explanation:

i got it on study island and make sure you copy this "the part of the earth and its atmosphere in which living organisms exist or that is capable of supporting life." and do ctrl f and paste and check where your answer is because the answer might be shuffled hope you have a great day!! :)

The part of the earth and its atmosphere in which living organisms exist or that is capable of supporting life. Thus option A is correct.

The atmosphere is a gas that cover the a planet and is present in place by the gravitational force of the planet, the temperature of the atmosphere is low.

The atmosphere is composed of nitrogen (78%), oxygen (21%), argon (0.9%), carbon dioxide (0.04%) and trace gases, variable amount of water vapor are also present .

Carbon dioxide gas is responsible mainly for the greenhouse effect, transparent to the incoming solar radiation but is opaque to the outgoing terrestrial radiation.

Dust particles are  present in the atmosphere, these particles act as hygroscopic nuclei around which water vapor condenses to produce clouds.

Thus option A is correct.

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Because it is just simply bigger a na is way way smaller than a ci.

Ionic radii of cations:

When you form a metal cation, you are removing the outermost electrons and revealing the inner core.  

For example, to form an Na⁺ ion you must remove a 3s electron from an Na atom, exposing the 2s and 2p subshells.

The n = 2 shell is smaller than an n= 3 shell, so an Na⁺ ion is smaller than an Na atom (as in the image below).

Ionic radii of anions:

When you form an anion, you are adding electrons to the outermost shell. These electrons (a) increase the shielding from the nucleus and (b) repel all the other electrons.  

The decreased nuclear attraction and the electronic repulsions cause the electron cloud to expand, so a Cl⁻ ion is larger than a Cl atom.

Hey there!:

Temperature in kelvin : 45 + 273 => 318 K

Number of moles H2:

p * V = n * R * T

4.46 * 0.579 = n * 0.082 * 318

2.58234 = n * 26.076

n = 2.58234 / 26.076

n = 0.09903 moles of H2O

Given the reaction:

XeF6(s) + 3 H2(g) → Xe(g) + 6 HF(g)

Molar  mass XeF6 = 245.3 g/mol

0.09903 mol H2O *  ( 1 mol XeF6 / 3 mol H2 ) * 245.3

= 8.09 g of XeF6

Hope that helps

The smallest and the basic particle of a chemical element is said to be an atom. It is made up of three subatomic particles that is electrons, protons and neutrons.  The neutrons and protons are present in the nucleus of an atom whereas electrons are present in the orbits around the nucleus of the atom.  There are several shells in the orbital depending on the atomic number.  The electrons which are present in the outermost shell are said to be valence electrons.

They can be determined by the electronic configuration of the element.

The atomic number of strontium, [tex]Sr[/tex] is 38. The electronic configuration of strontium, [tex]Sr[/tex] is:

[tex]1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}[/tex]

From the electronic configuration it is clear that the outermost shell of strontium, [tex]Sr[/tex] is [tex]5s[/tex]. So, the number of valence electrons in strontium, [tex]Sr[/tex] is 2.

Hence, there are 2 valence electrons in an atom of strontium ([tex]Sr[/tex]).

The number of valence electrons are in an atom of strontium (Sr) is 2 and the correct option is option B.

Atomic number is the number of protons present in the nucleus of an atom. It is always equal to the number of electrons in orbit about that nucleus (in a nonionized atom). Thus, all atoms that have the same number of protons--the atomic number--are atoms of the same element.

The modern periodic table is arranged in such a way that all the elements have an increasing atomic number, and subsequently, increasing mass number.

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Answer:- C. Hafnium.

Solution:- Mass of the sample is 46.0 g and it's volume is [tex]3.5cm^3[/tex] .

From mass and volume, we can calculate it's density using the formula:

[tex]density=\frac{mass}{volume}[/tex]

[tex]density=\frac{46.9g}{3.5cm^3}[/tex]

[tex]density=\frac{13.4g}{cm^3}[/tex]

On the basis of the density, this substance could either be mercury or hafnium. Since the substance is a solid at room temperature where as mercury is liquid. So, it can't be mercury.

The right choice is C) Hafnium.

Answer:

the one above me

Explanation: