why do comets have tails

Ionic bond is described as the chemical bond between two oppositely charged ions. In ionic bond the metal loses electron forming a positively charged cation and a non metal which accept the cation to form a negatively charged anion. In ionic bond the atoms are held together by electrostatic force of attraction. In ionic bond the anions and cations are present in the ratio where the total charge of the compound becomes zero. For example, Let us consider NaCl compound. An atom of the sodium has three electrons in its valency shell and the electrons are removed from the outer most shell by applying the energy of 5.14 electron volts. The chlorine atom lacks an electron to attain stable electronic configuration and it accepts the electron from the sodium by releasing 3.62 electron volts of energy which means that it takes only 1.52 electron volts of energy to donate an electron to chlorine when both the atoms are far apart. When these electrons are brought together their electric potential becomes more negative. This means that if the neutral sodium and chlorine atoms are found themselves closer it would be energetically favourable to transfer electrons from sodium to chlorine thus resulting in the formation of the ionic bond.

The ions in an ionic bond are held together by electrostatic attraction between the anions and cations in the compound.

For example, sodium chloride [NaCl] (more commonly known as salt) has positively charged sodium [Na+] ions, or cations, and negatively charged chlorine [Cl-] ions, or anions, holding the compound together.

The lowest layer of Earth's atmosphere is called troposphere.The layer immediately next to troposphere is called Stratosphere. The boundary layer between troposphere and stratosphere is described as tropopause.

The tropopause is the transition layer between the troposphere and the stratosphere in Earth's atmosphere. It is located at an altitude of about 12-15 km, and it is the coldest part of the atmosphere.

The tropopause can be defined as the transition layer between the troposphere and the stratosphere in Earth's atmosphere. It is located at an altitude of about 12-15 km (7-8 miles), and it is the coldest part of the atmosphere. The temperature in the troposphere decreases steadily with increasing altitude, but at the tropopause, the temperature starts warming again due to the absorption of UV radiation by ozone in the stratosphere.

Your answer is A

6.02 × 1023 particles

Answer: [tex]6.022\times 10^{23}[/tex]

Explanation: According to Avogadros law, one mole of any substance contains a fixed number of particles i.e [tex]6.022\times 10^{23}[/tex] particles (atoms, molecules or ions) which is also known by the name Avogadro's number.

For example: 1 mole of [tex]O_2[/tex] molecule contains [tex]6.022\times 10^{23}[/tex] molecules of oxygen.

1 mole of [tex]He[/tex] contains [tex]6.022\times 10^{23}[/tex] atoms of helium.

Final answer:

2.00 g of oxygen is produced ,option B

Explanation:

To determine how many grams of oxygen are produced when 11.5 g of NO2 is formed, we can use the stoichiometry of the balanced chemical equation:

2 Pb(NO3)2(s) = 2 PbO(s) + 4 NO2(g) + O2(g)

From the equation, we see that 4 moles of NO2 are produced alongside 1 mole of O2. First, we find the number of moles of NO2 that 11.5 g corresponds to:

Molar mass of NO2 = 14.01 (N) + (2 *16.00) (O) = 46.01 g/mol

Moles of NO2 = 11.5 g / 46.01 g/mol

Then, we take into account the mole ratio between NO2 and O2, which is 4:1:

Moles of O2 = (Moles of NO2)  times (1 mole O2 / 4 moles NO2)

Finally, we find the mass of O2 produced:

Molar mass of O2 = 2  times 16.00 g/mol = 32.00 g/mol

Mass of O2 = (Moles of O2)  times (32.00 g/mol)

By going through the calculations, we find that the mass of O2 produced is 2.00 g, which corresponds to option (b).

It will be B.) A force equal to the force keeping the object at rest, but in the opposite direction.

Generally when we move down the group on a periodic table the atomic radii increases as the valency electrons occupy higher levels due to the increasing quantum number. Hence the atomic radii increases down the group.

The ionic radii increases down the group because while we move down the group the elements gain electrons and form ions called anions as an additional electron occupies the orbital the ions get bigger in size. Hence the ionic radii increase.

Electronegativity is described as the ability to attract and bind with electrons and it is a qualitative property. It decreases as we move down the group because the distance between the valency electrons and the nucleus increases. Hence electronegativity decreases down the group.

Reactivity increases as we move down the group as the metals have the tendency to lose electron form its outer shell.

Therefore the answer is ionic radii increases.

The frequency of radio waves at the two stations are:

1. WIL-92.3 : Frequency = 92.3 MHz (mega hertz)

2. KSHE-94.7 : Frequency = 94.7 MHz

The wavelength (λ) and frequency (ν) are related as:

ν = c/λ ------(1)

Energy (E), frequency (ν) and wavelength (λ) are related as:

E = hν -----(2)

(or)

E = hc/λ ----(3)

A) Based on equation (2), higher the frequency higher is the energy. Therefore, station KSHE broadcasts waves with higher energy

B) Based on equation (1), higher the frequency lower will be the wavelength. Station KSHE will broadcast waves with shorter wavelength

C) KSHE will broadcast waves with higher frequency

Station KSHE-94.7 broadcasts waves with more energy, a shorter wavelength, and a higher frequency compared to WIL-92.3, as higher frequencies correspond to more energy and shorter wavelengths.

In comparing radio wave broadcasts of WIL-92.3 and KSHE-94.7, we need to consider frequency, energy, and wavelength properties of radio waves. Here is how they relate:

Given that,:

Therefore, all the three properties are higher for KSHE-94.7 as compared to WIL-92.3.

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Answer: 66.66 ml

Explanation: Using Molarity equation:

[tex]M_1V_1[/tex] (stock solution)=[tex]M_2V_2[/tex](solution to be prepared)

given: [tex]M_2=0.750M[/tex]

[tex]V_2=800ml[/tex]

[tex]M_1=9.00M[/tex]

[tex]V_1=?[/tex]

[tex]9.00M\times V_1[/tex] (stock solution)=[tex]0.750M\times 800ml[/tex] (solution)

[tex]V_1= 66.66ml[/tex]

Heat energy released here

Q = mass x specific heat capacity of water x deltaT

= 25.0 x 4.184 x (-10.0)

= - 1046 Joules

1046 Joules of heat energy is released in this process.  

Answer: The amount of heat released is -1046 J

Explanation:

To calculate the amount of heat released, we use the equation:

[tex]q=mc\Delta T[/tex]

where,

q = heat released = ?

m = mass of water = 25.0 g

c = specific heat capacity of water = 4.184 J/g.°C

[tex]\Delta T[/tex] = change in temperature = [tex]T_2-T_1=(10.0-20.0)^oC=-10.0^oC[/tex]

Putting values in above equation, we get:

[tex]q=25.0g\times 4.184J/g.^oC\times (-10.0^oC)\\\\q=-1046J[/tex]

Hence, the amount of heat released is -1046 J

Answer:

B. 2.12 L  

Step-by-step explanation:

We know we will need a balanced chemical equation with masses and molar masses, so, let's gather all the information in one place.

M_r:                   32.00

        4NH₃(g) + 7O₂(g) ⟶ 4NO₂ + 6H₂O(g)

m/g:                      5.3

(a) Moles of O₂

Moles of O₂ = 5.3 × 1/32.00

Moles of O₂ =0.166 mol

=====

(b) Moles of NH₃

The molar ratio is 4 mol NH₃= 7 mol O₂.

Moles of NH₃ = 0.166 × 4/7

Moles of NH₃ = 0.0946 mol NH₃

=====

(c) Volume of NH₃ at STP

STP is 1 bar and 0 °C. At STP, the molar volume of a gas is 22.71 L.

Volume of NH₃ = 0.0946 ×22.71/1

Volume of NH₃ = 2.15 L

=====

It looks as if you are using the old (pre-1982) definition of STP.

Under that definition, the molar volume of a gas at STP was 22.41 L.

The volume of NH₃ is then 2.12 L.

Answer: The correct answer is Option a and d.

Explanation: Both the salts are ionic in nature because when dissolved in water, they dissociate into their respective ions.

Ionic compounds are held together by ionic bond. They are neutral compounds as both positive and negative charges neutralize each other. These compounds are also good conductors of electricity because of the presence of ions.

As both the salts have different molecular formula, both of them will have different crystal lattice system and hence, different crystal lattice energy.

From the above information, the correct options are option a and option d.

Answer:

D

Explanation:

both a and b

that i a correct

answer

D. Same energy level but different sublevel.

There are four quantum numbers [1]:

As their names might suggest:

The two electrons in question come from the same atom. The question suggests that they have the same n, [tex]m_l[/tex], and [tex]m_s[/tex]. As a result, both electrons are in main energy level n = 3. They share the same spin.

However, the two electrons differ in their value of l.

[1] Kamenko, Anastasiya, et. al, "Quantum Numbers", Physical & Theoretical Chemistry, Chemistry Libretexts, 24 Mar 2017.

B. the freedom of electrons in the metallic bonding

Answer: Option (B) is the correct answer.

Explanation:

Copper is known as the best conductor of heat and electricity. This is because in copper there is availability of free electrons.

And, as it is known that electricity is the flow of electrons. This means that since copper metal contains a number of free electrons. Hence, it can easily conduct electricity.

Electronic configuration of copper is [tex][Ar]4s1 3d^{10}[/tex]

Thus, we can conclude that freedom of electrons in the metallic bonding at molecular level property allows copper to be an ideal material to be used in electrical wiring.

Answer:

0.726 mol·L⁻¹

Step-by-step explanation:

c = moles/litres

=====

Moles = 29.8 × 1/342.30

Moles = 0.087 06 mol

=====

Litres = 120 × 1/1000

Litres = 0.120 L

=====

c = 0.087 06/0.120

c = 0.725 mol·L⁻¹

B. Is the Answer 6.022 * 1023

Answer: B) [tex]6.022\times10^{23}[/tex] atoms.

Explanation:

According to the International System of units ,

A mole is basically denotes a unit that contains [tex]6.022\times10^{23}[/tex] of atoms.

It is also known as Avagadro Number.

Similarly,  the number of atoms in one mole of gold = [tex]6.022\times10^{23}[/tex]

hence, the correct answer is B) [tex]6.022\times10^{23}[/tex] atoms.

The answer is: D) O, F, and Kr.

Atomic radius of bromine (Br) is 114 pm.

Atomic radius of oxygen (O) is 73 pm.

Atomic radius of fluorine (F) is 72 pm.

Atomic radius of krypron (Kr) is 112 pm.

The atomic radius of a chemical element is a measure of the size of its atom.

The atomic radius varies with increasing atomic number, but usually increases because of increasing of number of electrons.

The atomic radius decreases across the periods because an increasing number of protons, because greater attraction between the protons and electrons.

Answer is: hydrogen bonding.

Methanol has stronger intermolecular bonds than methane.

Intermolecular forces are the forces between molecules or particles.

There are several types of intermolecular forces: hydrogen bonding, ion-induced dipole forces, ion-dipole forces andvan der Waals forces.

Hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (H), covalently bound to a highly electronegative atom such as flourine (F), oxygen (O) and nitrogen (N) atoms.

Answer is: B) Wind produced by the uneven heating of Earth's surface.

Gasoline is a mixture  of many different hydrocarbons: alkanes (paraffins), cycloalkanes and alkenes (olefins). It is not renewable resource, because every year is less and less gasoline.

Natural gas is usualy methane, it is not renewable recourse.

Wind consists of the bulk movement of air.

Final answer:

Wind produced by the uneven heating of Earth's surface is the renewable resource among the options provided.

Explanation:

Among the listed options, the renewable resource is B) Wind produced by the uneven heating of Earth's surface. Renewable energy sources such as wind can be replenished within a human timescale and do not deplete. Gasoline, even if it contains some alcohol, is not renewable because it is derived from petroleum which is a finite resource. Natural gas, while it may be used alongside renewable resources, is also non-renewable as it cannot be replenished within a human timescale once it's extracted from deep underground.

Answer:

106.6 °C  

Step-by-step explanation:

The formula for boiling point elevation ΔTb is

ΔTb = iKb·b

where

i     = the van't Hoff i# factor

Kb = the molal boiling point elevation constant

b   = the molal concentration of the solution

=====

Data

  i = 2, because 1 mol of NaCl gives 2 mol of ions in solution.

Kb = 0.51 °C·mol·kg⁻¹

 b = 1.00/0.155

 b = 6.452 mol·kg⁻¹

=====

Calculations

ΔTb = 2 × 0.51 × 6.452

ΔTb = 6.58°C

 Tb = Tb° + ΔTb

 Tb = 100 + 6.58

 Tb = 106.6 °C

Isotopes of the same element have identical numbers of protons and electrons (in a neutral state), and thus they share the same atomic number. They differ in the number of neutrons they possess, which leads to different atomic masses.

The question concerns isotopes of the same element. Two key characteristics of isotopes are their atomic number, which remains constant because isotopes have the same number of protons, and their varied atomic mass due to a different number of neutrons.

Isotopes have the same number of protons.

Isotopes have the same number of electrons (if the atom is in a neutral state).

Isotopes have the same atomic number.

Statements about isotopes having the same number of neutrons or the same atomic mass are incorrect; these are the properties that distinguish one isotope of an element from another.

The true statements are:

a) Isotopes have the same number of protons.

b) Isotopes have the same number of electrons.

e) Isotopes have the same atomic number.

Isotopes are variations of the same element that have the same number of protons, but different numbers of neutrons. This means they have different mass numbers, which is the sum of protons and neutrons in the nucleus. Here are the true statements about isotopes of the same element:

Isotopes have the same number of protons: The number of protons (atomic number) defines the element. All isotopes of an element have this same atomic number.

Isotopes have the same number of electrons: In a neutral atom, the number of electrons is equal to the number of protons. Therefore, isotopes of the same element have the same number of electrons.

Isotopes have the same atomic number: Because the atomic number is defined by the number of protons, which is consistent across isotopes of an element, the atomic number remains the same.

1) Answer is: False.

Balanced chemical reaction: Pb + AlCl₃ → no reaction.

The reactivity series is a series of metals from highest to lowest reactivity. Metal higher in the reactivity series will displace another.

Aluminium (Al) is higher in activity series than lead (Pb).

That means aluminium (Al) is stronger reducing agent than lead and gives electrons easier.

This series are used to summarize information about the reactions of metals with acids or water, double displacement reactions (more reactive metals displace metals with lower reactivity) and the extraction of metals from their ores.

2) Answer is: Na3PO4 + 3KOH → 3NaOH + K3PO4, because K retains the same charge throughout the reaction.

This chemical reaction is double displacement reaction - cations (K⁺ and Na⁺) and anions (PO₄³⁻⁻ and OH⁻) of the two reactants switch places and form two new compounds.

Na₃PO₄ is sodium phosphate.

KOH is potassium hydroxide.

NaOH is sodium hydroxide.

K₃PO₄ is potassium phosphate.

3) Answer is: Zn + H2SO4 → ZnSO4 + H2.

Single replacement is reaction where neutral element metal or nonmetal become an ion as it replaces another ion in a compound.

In this balanced chemical reaction zinc (Zn) replaces hydrogen (H).

Zinc changes oxidation number from 0 to +2 (this is oxidation) and hydrogen change oxidation number from +1 to 0 (reduction).

4) Answer is: A single replacement reaction takes place because sodium is more reactive than hydrogen.

Balanced chemical reaction:

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g).

Single replacement is reaction where neutral element metal or nonmetal become an ion as it replaces another ion in a compound.

In this balanced chemical reaction sodium (Na) replaces hydrogen (H).

Sodium changes oxidation number from 0 to +1 (oxidation) and hydrogen change oxidation number from +1 to 0 (reduction).

5) Answer is: True.

For example, balanced chemical reaction:

Ca + 2HCl → H₂ + CaCl₂.

Reduction hald reaction: 2H⁺ + 2e⁻→ H₂.

Oxidation half reaction: Ca⁰ → Ca²⁺ + 2e⁻.

In this balanced chemical reaction calcium (Ca) replaces hydrogen (H).

In this chemical reaction, calcium lost two electrons (oxidation, change oxidation number from 0 to +2) and hydrogen gain that two electrons (reduction, change oxidation number from +1 to 0).

6) Answer is: It is a single replacement reaction, and the cations in the two ionic compounds are different.

For example, balanced chemical reaction:  

Ba + MgSO₄ → BaSO₄(s) + Mg.

In this balanced chemical reaction barium (Ba) replaces magnesium (Mg), because barium is higher at activity series.

Sulfate anion (SO₄²⁻) is the same in two ionic compounds, but cations (Mg²⁺ and Ba²⁺) changes.

Single Displacement is reaction where neutral element metal or nonmetal become an ion as it replaces another ion in a compound.  

16) Chemical equation: Ca + H₃PO₄ → Ca₃(PO₄)₂ + H₂.

Oxidation reaction: Ca⁰ → Ca⁺² + 2e⁻ /×3.

3Ca⁰ → 3Ca⁺² + 6e⁻

Reduction reaction: 6e⁻ + 2H₃⁺¹ → 3H₂⁰.

Calcium change oxidation number from 0 to +2 (oxidation) and hydrogen change oxidation number from +1 to 0 (reduction).

Balanced chemical equation: 3Ca + 2H₃PO₄ → Ca₃(PO₄)₂ + 3H₂.

Calcium is stronger reducing agent than hydrogen, gives electrons easier.

This is example of single displacement reaction.

Single displacement is reaction where neutral element metal or nonmetal become an ion as it replaces another ion in a compound.

17) Balanced chemical equation:

3Ca(s) + 2H₃PO₄(aq) → Ca₃(PO₄)₂(aq) + 3H₂(g).

Ionic equation: 3Ca + 6H⁺ + 2PO₄³⁻ → 3Ca²⁺ + 2PO₄³⁻ + 3H₂.

Net ionic equation: 3Ca + 6H⁺ → 3Ca²⁺ + 3H₂.

A spectator ion is an ion that exists as a reactant and a product in a chemical equation.

A spectator ion is phospate anion PO₄³⁻.

So the equation is,

2Cl2(g) + 7O2(g) + 130kcal -> 2Cl2O7(g)

from this , ΔH°rxn=[tex]130kcal.mol^{-1}[/tex]

[tex]mol^{-1}[/tex] is mentioned because it is for per mole of reaction. So for 4. moles of the product [tex]2Cl_{2} O_{7}[/tex] we need 4/2 moles of reaction to be used to calculate associated enthalphy change for the reaction.

Therefore[tex]4/2*130=260 kcal[/tex]

Since the C is bonded to 2 H atoms,

it needs two more bonds to complete the octet of C(as C forms four bonds in total),hence C-C bond is double covalent bond

The bonded C atom is shown as bold C here:

-C=CH2

The  bond between the two C atoms is Double Covalent.

The type of bond that exists between the two carbon atoms in this organic compound is a double covalent bond.

In a double covalent bond, two pairs of electrons are shared between the two carbon atoms. Each carbon atom contributes one electron from its outermost electron shell to form a strong and stable bond. This sharing of electrons allows both carbon atoms to satisfy the octet rule, which states that atoms tend to gain, lose, or share electrons to achieve a stable configuration with a full outer electron shell, typically containing eight electrons.

Covalent bonds occur when atoms share electrons to achieve a stable electron configuration. In the case of a double covalent bond, there are two pairs of shared electrons between the two carbon atoms. This bond is strong and requires a significant amount of energy to break, making it a key characteristic of many organic compounds with double bonds, such as alkenes and some functional groups in organic chemistry.

To learn more about electrons, click here.

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You can solve this by utilizing the ideal gas law, PV=nRT. P is pressure, V is volume, n is the number of moles, R is a constant (depends on the unit of pressure), and T is the temperature (in Kelvins).

500.0mmHg- convert to atm

=0.65789atm (do sig figs last)

25.0 C- convert to K

25.0 +273= 298K

PV=nRT

0.65789atm times 45.0L equals n (the variable) times R (0.08206L atm mol^-1 K^-1) times 298K

Isolate the variable, n and plug into a calculator.

I hope this helped!

Answer: The moles of gas is 1.21 moles.

Explanation:

To calculate the moles of gas, we use the equation given by ideal gas which follows:

[tex]PV=nRT[/tex]

where,

P = pressure of the gas = 500.0 mmHg  

V = Volume of the gas = 45.0 L

T = Temperature of the gas = [tex]25^oC=[25+273]K=298K[/tex]

R = Gas constant = [tex]62.364\text{ L.mmHg }mol^{-1}K^{-1}[/tex]

n = number of moles of gas = ?

Putting values in above equation, we get:

[tex]500.0mmHg\times 45.0L=n\times 62.3637\text{ L.mmHg }mol^{-1}K^{-1}\times 298K\\\\n=\frac{500.0\times 45.0}{62.364\times 298}=1.21mol[/tex]

Hence, the moles of gas is 1.21 moles.

The enthalpy of combustion of magnesium in this experiment is approximately -602 kJ/mol, which was determined by dividing the total heat transferred (calculated from the calorimeter's heat capacity and temperature change) by the number of moles of magnesium burnt.

In the experiment described, a small piece of magnesium was burnt in a oxygen bomb calorimeter, leading to a recorded temperature rise in the calorimeter and the water it contains. The enthalpy of combustion of magnesium can be determined from these values by using the equation q = mcΔT, where q is the heat transferred, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature. In this case, the total heat transferred (q) is the heat capacity of the calorimeter and the water times the temperature change, or 5760 J/°C * 0.570 °C = 3283.2 J. The molar enthalpy of combustion can then be calculated by determining the moles of Mg burnt (0.1326 g / 24.305 g/mol = 0.00545 mol) and dividing the heat produced by the moles of Mg burnt (3283.2 J / 0.00545 mol = -602 kJ/mol). Therefore, when rounded to 3 significant figures, the enthalpy of combustion of magnesium is around -602 kJ/mol.

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Momentum = mass x velocity 750x25 = 18750 kg-m/s.

  Cu + 2HCI → Cu²⁺ + 2CI⁻ + H2(g)

has an overall reduction potential of –0.34 V      

The correct option is:

The reaction is not spontaneous and will require energy to proceed.

Since  the overall reduction potential is negative,the reaction is not spontaneous and it requires energy to proceed.

The reaction is

Cu(s) + 2HCI(aq)  ---> Cu⁺² + 2CI⁻ + H₂(g)

The given E⁰cell = -0.34

The overall reduction potential is negative

A reaction is said to be spontaneous it is ΔG° is negative

The relation between ΔG° and Electrode potential is

ΔG° = -nFE°cell

as given that

E°cell = -0.34 V

The overall value of ΔG° will be positive and hence reaction must be non spontaneous

so

The reaction is not spontaneous and will require energy to proceed.