What is the number of elements in 2Ca(OH)2

The equation for the overall reaction obtained by adding these equations is;  2NO₂(g) ⇒ N₂O₄(g)

We are given equations;

2NO₂(g) ----> 2NO(g) + O₂(g)   ---(1)

2NO(g) -----> N₂(g) + O₂(g)   -----(2)

N₂(g) + 2O₂(g) ----> N₂O₄(g)   -----(3)

Add eq 1 and eq 2 to get;

2NO₂(g) + 2NO(g) ⇒ 2NO(g) + O₂(g) + N₂(g) + O₂(g)

2NO will cancel out to get;

2NO₂(g) ⇒ N₂(g) + 2O₂(g)   -----(4)

Add eq 3 to eq 4 to get;

N₂(g) + 2O₂(g) + 2NO₂(g) ⇒ N₂O₄(g) + N₂(g) + 2O₂(g)

This will reduce to;

2NO₂(g) ⇒ N₂O₄(g)

The correct question is;

Consider the chemical equations shown here.

2NO₂(g) ----> 2NO(g) + O₂(g)

2NO(g) -----> N₂(g) + O₂(g)

N₂(g) + 2O(g) ----> N₂O₄(g)

What is the equation for the overall reaction obtained by adding these equations?

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Answer:

A &D

Explanation:

I took it

The combination in Option D , NaCl + HCl  is not a buffer

A buffer is a solution which is added to resist changes in pH when a small amount of acid.

It is generally made of weak base with its conjugated acid ,  weak acid with its conjugated base.

A buffer comes with a defined with a capacity .

Among the given option the solution mixture  which is not a buffer is

NaCl + HCl

as a buffer is not made of a strong acid and its salt.

Therefore Option D is not a buffer.

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Answer:

d

Explanation:

k-shell has the greatest binding energy

Empirical formula of the Cyclopropane = C[tex]H_{2}[/tex]

Molecular formula  of the Cyclopropane = [tex]C_{3} H_{6}[/tex]

Cyclopropane is a cyclic compound having 3 carbon atoms in a ring.

As we know carbon is having 4 valency, that means it can form 4 bonds with other atoms.

In case of cyclopropane each carbon atom is attached with 2 carbon atoms in a ring, so 2 valency of each carbon atom is used in a ring formation.

The remaining 2 valency are satisfied by hydrogen atoms.

Here, 3 carbons are there so 6 hydrogens are used to satisfy their valency.

An empirical formula is a simple representation of ratio of the atoms present, while a molecular formula is a detailed representation of the total number of atom.

So here, carbon and hydrogen ratio is 1:2 , from this the Empirical formula of the Cyclopropane became C[tex]H_{2}[/tex]

And the molecular formula of  the Cyclopropane is [tex]C_{3} H_{6}[/tex].

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Transient stage is also called the unstable stage and in this stage, there is a gradual decrease in deformation rate to a definite constant value.

A transient state is when a process variable or variables changes, but before the system reaches a steady state.

Transient time is the time it takes for a circuit to change from one steady state to the next.

Therefore, Transient stage is also called the unstable stage and in this stage, there is a gradual decrease in deformation rate to a definite constant value.

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Answer:

Option 1

Explanation:

You need to make the number of each type of atom on both sides the same, and this can only be done by changing the coefficients.

The number of moles of N₂ contained in the flask will be 0.607.

According to Boyle's law, the pressure of a gas tends to drop as the capacity of the container increases. The ideal gas equation is formed from the Boyles and Charles law.

Given data,

Pressure,P= 2.86 ATM

Volume,V = 5.00 L

Universal gas constant,R= 0.08206 L atm/mol K

Temperature,T= 13.86 °C = 286.8 K

From the ideal gas equation;

PV=nRT

2.86 × 5 = n × 0.08206 × 286.8

n = 0.607 moles

Hence the number of moles of N₂ contained in the flask will be 0.607.

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Given the model from the question,

From the model given, we obtained the ffolowing

Thus, we can write the balanced equation as follow:

3H₂ + 2NO —> N₂ + 2H₂O + H₂

From the balanced equation above,

3H₂ + 2NO —> N₂ + 2H₂O + H₂

From the balanced equation above,

3 moles of H₂ reacted with 2 moles of NO.

Therefore,

5 moles of H₂ will react with = (5 × 2) / 3 = 3.33 moles of NO

From the calculation made above, we can see that only 3.33 moles of NO out of 4 moles given are required to react completely with 5 moles of H₂.

Thus, H₂ is the limiting reactant

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Thomson discovered the electron, the first subatomic particle. In 1904, Thomson proposed atomic model where electrons are embedded within spherically distributed, positive charge (so-called "plum pudding" model).

J.J. Thomson's experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. Thomson proposed the plum pudding model of the atom, which had negatively-charged electrons embedded within a positively-charged "soup."

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The ionization energy will increase substantially when 11th electron is removed compared to when the 10th electron is removed.

Ionization energy is the energy required to remove one or more electrons from a neutral atom in its gaseous state to form a positively-charged ion.

The ionization energy increases steadily as successive electrons are removed from an atom. A substantial increase in ionization energy occurs with the removal of an electron from a filled inner shell.

The 10th electrons is the last electron in the L shell of atoms. The 11th electron is the first electron in a  filled inner shell.

Therefore, ionization energy will increase substantially when 11th electron is removed compared to when the 10th electron is removed.

Note that there was no attached graph and the answer was given based on the general trend observed in ionization energies.

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Considering the definition of STP conditions and Avogadro's number, the number of molecules of gas present in 2.24 L is 6.023×10²² molecules.

The STP conditions refer to the standard temperature and pressure. Pressure values at 1 atmosphere and temperature at 0 ° C are used and are reference values for gases. And in these conditions 1 mole of any gas occupies an approximate volume of 22.4 liters.

Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023×10²³ particles per mole. Avogadro's number applies to any substance.

At STP, 2.24 L of carbon dioxide gas is collected. So, you can apply the following rule of three: if by definition of STP conditions 22.4 L are occupied by 1 mole of carbon dioxide gas, 2.24 L are occupied by how many moles of carbon dioxide gas?

[tex]amount of moles of carbon dioxide gas=\frac{2.24 Lx1 mole}{22.4 L}[/tex]

amount of moles of carbon dioxide gas= 0.1 moles

Finally, 0.1 moles of carbon dioxide gas are collected.

Then you can apply the following rule of three, considering the Avogadro's number:  If 1 mole of carbon dioxide gas contains 6.023×10²³  molecules, 0.1 mole of carbon dioxide gas contains how many molecules?

amount of molecules of carbon dioxide gas= (6.023×10²³ molecules × 0.1 moles)÷1 mole

amount of molecules of carbon dioxide gas=6.023×10²² molecules

Finally, the number of molecules of gas present in 2.24 L is 6.023×10²² molecules.

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The atom present in Option (1) most likely to form cation with a charge of +1

A cation has more protons than electrons, consequently giving it a net positive charge.

For a cation to form, one or more electrons must be lost, typically pulled away by atoms with a stronger affinity for them.

The atoms present in Option 1 have one eletron in its outermost shell therefore, it is easy for the atom to lose one elecron than more electron  and to attain stable electronic confiuration.

Hence, The atom present in Option (1) most likely to form cation with a charge of +1

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When One mole of hydrogen is burned in oxygen to produce water in the gas phase, 285.8 kJ of heat is released.Hence, option (D) is correct

An enthalpy change is approximately equal to the difference between the energy used to break bonds in a chemical reaction and the energy gained by the formation of new chemical bonds in the reaction.

It describes the energy change of a system at constant pressure. Enthalpy change is denoted by ΔH.

The energy change that occurs when one mole of a compound is burnt in excess oxygen under standard bis called the standard enthalpy change of combustion.

Hence, When One mole of hydrogen is burned in oxygen to produce water in the gas phase, 285.8 kJ of heat is released.Thus, option (D) is correct

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Answer:

c

Explanation:

because heat is taken in in sublimation.

Sublimation is the straight transition from a solid state of materials to a vapor state upon heating (without becoming liquid). The row about a change of state which is correct is C.

Sublimation is the transition of a substance from its solid to its gaseous state without passing through a liquid phase. Sublimation is the term most frequently used to describe the process by which snow and ice turn into water vapor (gas) in the atmosphere without first melting into a liquid for those of us who are interested in the water cycle.

The best illustration of sublimation is dry ice, which is carbon dioxide that has been frozen. Dry ice directly transforms from its solid state to a gaseous state, which is visible as fog, when it is exposed to air. The gaseous state of frozen carbon dioxide is more stable than the solid state.

Thus the correct option is C.

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Answer:

an x-ray a photographic or digital image of the internal composition of something, especially a part of the body, produced by X-rays being passed through it and being absorbed to different degrees by different materials.

examples

Abdominal x-ray.

Barium x-ray.

Bone x-ray.

Chest x-ray.

Dental x-ray.

Extremity x-ray.

Hand x-ray.

Joint x-ray.

Explanation:

its uses

An X-ray is a common imaging test that's been used for decades. It can help your doctor view the inside of your body without having to make an incision. This can help them diagnose, monitor, and treat many medical conditions.

CH3 CH₂OH + 30₂ → 2CO₂ + 3H₂O

If the balloon had a volume of 3 L at a depth of 50 m, the original volume of the balloon will be

Significant figures are the number of digits in a value, often a measurement, that contribute to the degree of accuracy of the value.

The pressure at a depth of 40 m is the hydrostatic pressure of the water plus the atmospheric pressure.

The hydrostatic pressure P of a liquid is given by the formula ;

P = ρgh

where,

P =  1000 kg m⁻³ x 9.81 ms⁻² x 50 m

   = 1000 kg m⁻¹ x 9.81 s⁻² x 50

   = 4.9 x 10⁵ Pa

Lets's Convert Pa in to atm

    =   4.9 x 10⁵ Pa x 1 / 103. 325 x 10³ Pa

    = 4.7 atm

Mow, lets calculate P(atm) ;

P(atm) = 14.7 psi x 1 atm / 14.7 psi

          = 1 atm

Total Pressure at 50 m is ;

P(total) = 4.7 atm + 1 atm

            = 5.7 atm

Now we can apply Boyle's Law to calculate the volume of the balloon at the surface.

P₁V₁ = P₂V₂

V₂ = P₁V₁ / P₂

According to the question ;

V₂ = 3 L x 5.7 atm  / 1 atm

     = 17.1 L

     = 20 L ( 1 significant figure)

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Answer:

1. Thermometer– It is used to measure air temperature.

2. From time to time– In 2–4hrs after sunrise, the air temperature rises the fastest. Around 1hr before sun set, the air temperature drops the fastest. The solar radiation reaches its highest value at noon.

3. Anemometer– it is used to measure wind speed and direction.

4. Direction– The wind vane originally measures the direction of the wind, but, some modern ones have wind cups attached to them, to measure the wind speed.

5. Anemometer– It is a device that measures wind speed and direction. These, days, some modern wind vanes also measure wind speed.

Explanation:

I hope this helps.

Answer:

3 ZnS (s) + 2 AIP(s) ---> AI₂S₃(s) +  Zn₃P₂(s)

Explanation:

I believe you are asking for this reaction to be balanced. However, after looking more closely, those are not the products that would be created from the reactants. Assuming this is a double-displacement reaction, and taking the most common charges of the ions into consideration, the actual products would be AI₂S₃(s) + Zn₃P₂(s). I apologize if I assumed incorrectly.

For an equation to be balanced, there needs to be the same amount of each element on both sides of the equation.

The unbalanced equation:

ZnS (s) + AIP(s) ---> AI₂S₃(s) + Zn₃P₂(s)

Reactants: 1 zinc, 1 sulfur, 1 aluminum, 1 phosphorus

Products: 3 zinc, 3 sulfur, 2 aluminum, 2 phosphorus

As you can see, there is an unequal amount of each element on the reactants and products side. To balance the equation, coefficients in front of the compound(s) will be necessary.

The balanced equation:

3 ZnS (s) + 2 AIP(s) ---> AI₂S₃(s) +  Zn₃P₂(s)

Reactants: 3 zinc, 3 sulfur, 2 aluminum, 2 phosphorus

Products: 3 zinc, 3 sulfur, 2 aluminum, 2 phosphorus

[tex]\quad \huge \quad \quad \boxed{ \tt \:Answer }[/tex]

[tex]\qquad \texttt {Observe a natural phenomenon}[/tex]

____________________________________

[tex] \large \tt Explanation \: : [/tex]

At first scientists/researchers observe a natural phenomenon. after enough observation, they make predictions why that phenomenon is happening and the reasons that lead to that particular phenomenon. then they generate scientific hypothesis to explain that phenomenon and after getting enough data they develop tests and perform experiments. And check the results they get and at last based on the results they conclude what actually is happening.

Answered by : ❝ AǫᴜᴀWɪᴢ ❞

Answer:

B.) It states that the change in enthalpy is independent of the pathway
the reaction takes to get to the products.

Explanation:

Hess's Law states that the overall enthalpy change is the sum of the enthalpy changes of all preceding steps. It does not matter how many steps there are or the type, so long as the enthalpy change of each is combined at the end, the overall change can be determined. The sequence (aka pathway) is not important.

Answer:

5.452  cal/g

Explanation:

45.8 cal / 8.4 g =   5.4523  cal/g

384.72 J is the heat of fusion of the substance.

It is the change in the value of the enthalpy by providing energy i.e. heat, for a specific quantity of the substance.

Given data:

Heat of fusion  =?

Mass of substance = 8.4 g

Unknown:

Amount of energy required to melt the given mass = 45.8 cal

Solution:

To solve this problem, the amount of energy required to melt the substance is given as;

H  = m L

m is the mass

L is the heat of fusion

Insert the given parameters and solve;

H  = 8.4 g  x 45.8 cal = 384.72 J

Hence, 384.72 J is the heat of fusion of the substance.

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Answer:

2 AlCl₃ + 3 Pb(NO₃)₂ ---> 2 Al(NO₃)₃ + 3 PbCl₂

Explanation:

This is a double-displacement reaction. The general structure of these reactions are:

AB + CD ----> AD + BC

In these reactions, the cation of one molecule is swapped with the cation of another molecule. To find the products, you first need identify the charge on each ion. This is important to know so that you can balance the new molecule via subscripts.

AlCl₃ = Al³⁺ and Cl⁻

Pb(NO₃)₂ = Pb²⁺ and NO₃⁻

Therefore, one of the new products should be a combination of Al³⁺ and NO₃⁻ and the other should be Pb²⁺ and Cl⁻. An easy way to balance the charges in the new molecules is to the make the charge on the cation the subscript of the anion (and vice versa). For instance, since Pb has a +2 charge, the chlorine should have a 2 subscript.

The unbalanced equation:

AlCl₃ + Pb(NO₃)₂ ---> Al(NO₃)₃ + PbCl₂

Reactants: 1 aluminum, 3 chlorine, 1 lead, 2 nitrate

Products: 1 aluminum, 2 chlorine, 1 lead, 3 nitrate

The balanced equation:

2 AlCl₃ + 3 Pb(NO₃)₂ ---> 2 Al(NO₃)₃ + 3 PbCl₂

Reactants: 2 aluminum, 6 chlorine, 3 lead, 6 nitrate

Products: 2 aluminum, 6 chlorine, 3 lead, 6 nitrate

Answer:

3.82 x 10²¹ molecules As₂O₃

Explanation:

To find the amount of molecules arsenic (III) oxide (As₂O₃), you need to (1) convert kg to lbs, then (2) convert g As₂O₃ to moles As₂O₃ (via molar mass), and then (3) convert moles to molecules (via Avogadro's number).

1 kilogram = 2.2 lb

Molar Mass (As₂O₃): 2(74.992 g/mol) + 3(15.998 g/mol)

Molar Mass (As₂O₃): 197.978 g/mol

Avogadro's Number:

6.022 x 10²³ molecules = 1 mole

0.0146 g As₂O₃            1 kg                  189 lb
------------------------  x  ---------------  x  ------------------  x   ................
         1 kg                     2.2 lb          

       1 mole                6.022 x 10²³ molecules
x  ------------------  x  ---------------------------------------  = 3.82 x 10²¹ molecules As₂O₃
      197.978 g                        1 mole

Answer:

I don't know ok sorry

Answer:

D

Explanation:

we use noble gas configuration of Kr because Kr atomic number is nearest to Sr

the atomic number of Kr and Sr

is equal to 36 and 38 based on this we write the electron configuration

1s2 ,2s2 , 2p6 , 3s2 , 3p6 , 4s2 , 3d10 , 4p6 === Kr and 5s2

Answer: D.

Explanation:

[Kr]5s2

Answer:

2290 . 75   J  absorbed

Explanation:

The copper changed from 21 to 28 degrees= 7 degrees

.85 kg = 850 gm

850 gm * 7 degrees * .385 J / g-degree) = 2290.75 j

The work function is 4.74eV if light frequency [tex]1.40 X 10^{15}[/tex] Hz strike a surface causing photoelectrons to leave with a KE of 1.05 eV.

When light whose frequency is more than the threshold frequency incident on the metal, electrons are emitted. Such electrons are called photoelectrons.

The photoelectric effect is a phenomenon in which a beam of light is projected towards a metal plate and this leads to the ejection of electrons from the metal. The minimum amount of energy required for this ejection of electrons is known as the work function. When the energy of the light beam is less than the work function, then the electrons are not emitted.

The photoelectric effect is represented by the equation:

E = φ + KE  where

E = energy of the incident photons

KE = kinetic energy of photoelectrons

φ = Work function of the metal

This can also be written in terms of frequency as:

h = h₀ +  [tex]\frac{1}{2}[/tex]mv²

h₀= frequency of the incident light beam

m = mass of the electron

v = velocity of the electron

h = Plank's constant 6.623 x 10⁻³⁴Js

Conversion factor: 1eV = 1.602 x 10⁻¹⁹ J

So, 1.05eV = 1.682 10⁻¹⁹ J

Using the formulas,

(6.623 x 10⁻³⁴Js)(1.40x10¹⁵ s⁻¹) = φ + 1.682 x 10⁻¹⁹ J

(9.272 x 10⁻¹⁹) - (1.682 x 10⁻¹⁹) = φ

φ = 7.590 x 10⁻¹⁹ J = 4.74 eV

Hence, the work function is 4.74eV if light frequency 1.40x10^15 Hz strike a surface causing photoelectrons to leave with a KE of 1.05 eV.

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