In his 1859 book On the Origin of Species, Charles Darwin stated
that modern organisms have evolved from common ancestors
through he process of
d
O adaptation
O evolution
diversification
O natural selection
pls help

Answer: The answer is D. The central atoms consist of two carbons.

Explanation:

Answer:

The central atoms consist of two carbons

Explanation:

Took the test! hope this helps!

Answer:

Option B. 71.4 amu

Explanation:

From the question given above, the following data were obtained:

Isotope A:

Mass of A = 69.95 amu

Abundance (A%) = 25.7%

Isotope B:

Mass of B = 71.95 amu

Abundance (B%) = 74.3%

Average atomic mass =..?

The average atomic mass of the element can be obtained as shown below:

Average atomic mass = [(Mass of A × A%)/100)] + [(Mass of B × B%)/100)]

= [(69.95 × 25.7)/100] + [(71.95 × 74.3)/100]

= 17.977 + 53.459

= 71.436 ≈ 71.4 amu

Therefore, the average atomic mass of the element is 71.4 amu

Answer:

The addition of NH₃⁺

Explanation:

A buffer is an aqueous mixture of a weak acid and its conjugate base or vice versa.

In ammonium iodide, NH₄I, the ions in solution are ammonium ion, NH₄⁺ and iodide ion, I⁻.

The iodide ion is the conjugate base of the HI, a STRONG ACID, that means the addition of HI in solution wouldn't produce a buffer.

And, NH₄⁺ is the conjugate acid of the NH₃, a WEAK BASE, that means the addition of NH₃ to the solution will produce a buffer: The mixture of a weak base, NH₃ and its conjugate acid, NH₄⁺

The two main postulates that was given by Antoine Lavoisier are, oxygen play an important role in combustion and the other is mass of reaction is always conserved. Therefore, the mass of the mixture is 1025g. the correct option is option C.

According to Law of conservation of mass, mass can neither be created nor be destroyed. Mass can only be transformed from one form to another. The law of conservation of mass was given by Antoine Lavoisier. Every reaction in nature follow the law given by Antoine Lavoisier that is mass is always conserved.

mass of salt+ mass of water=mass of solution

mass of salt =25 grams

mass of water=1,000 grams

substituting the given values, we get

25 grams+ 1,000 grams =mass of solution

mass of solution=1025g

Therefore, the mass of the mixture is 1025g. the correct option is option C.

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Answer:

9

Explanation:

Answer:

9

because i studied this

Answer:

[tex]m_{HCl}^{leftover}=7.50g[/tex]

Explanation:

Hello.

In this case, since the undergoing chemical reaction is:

[tex]HCl+NaOH\rightarrow NaCl+H_2O[/tex]

In order to identify the limiting reactant, we compute the available moles of sodium hydroxide (molar mass = 40 g/mol) and the moles of hydrochloric acid consumed by those moles via their 1:1 mole ratio considering the chemical reaction:

[tex]n_{HCl}=25.0gNaOH*\frac{1molNaOH}{40gNaOH} *\frac{1molHCl}{1molNaOH} =0.625molHCl[/tex]

Next, since the molar mass of hydrochloric acid is 36.46 g/mol, we compute the mass of that reactant that is actually consumed:

[tex]m_{HCl}=0.625molHCl*\frac{36.46gHCl}{1molHCl}=22.8gHCl[/tex]

In such a way, the leftover of HCl is:

[tex]m_{HCl}^{leftover}=30.3g-22.8g\\\\m_{HCl}^{leftover}=7.50g[/tex]

Best regards!

Answer:

2.88 g

Explanation:

First, let us look at the balanced equation of the reaction:

[tex]CaO(s) + H_2O (l) --> Ca(OH)_2(s)[/tex]

From the equation, 1 mole of CaO reacts with 1 mole of H2O to produce 1 mole of [tex]Ca(OH)_2[/tex].

mole = mass/molar mass

4.50 g of CaO = 4.50/56.08 = 0.08 mole

4.34 g of H2O = 4.34/18.02 = 0.24 mole

The ratio of moles of CaO and H2O should be 1:1, hence, H2O is in excess.

Excess mole of H2O = 0.24 - 0.08 = 0.16 mole

mass of 0.16 mole of H2O = mole x molar mass = 0.16 x 18.02 = 2.88 g

Therefore, 2.88 g of the excess reagent (water) would remain after the reaction is complete.

Answer: 22.78KJ/ mol

Explanation:

The computation of activation energy [tex]E_0[/tex] follows by formula:

[tex]\ln (\dfrac{K_2}{K_1}) = (\dfrac{E_a }{ R}) (\dfrac{1}{T_1} -\dfrac{ 1}{T_2})[/tex]

Given:[tex]T_1 = 376.0^{\circ}C =376+273K= 649 K[/tex]

[tex]K_1 = 4.8 \times10^8[/tex]

[tex]T_2 = 280.0^{\circ}C = 273+280K=553 K ,\ \ \ K_2 = 2.3 \times 10^8[/tex]

[tex]\ln(\dfrac{2.3 \times10^8 }{ 4.8 \times 10^8}) = (\dfrac{E_a }{ 8.314}) (\dfrac{1}{649} - \dfrac{1}{553})\\\\\Rightarrow\ \ln(0.479) = (\dfrac{E_a }{ 8.314}) (-\dfrac{96}{358897})\\\\\Rightarrow\ -0.73605468= (\dfrac{E_a }{ 8.314}) (-\dfrac{96}{358897})\\\\\Rightarrow\E_a=-0.73605468\times 8.314\times\dfrac{-358897}{96}=22878.033\\\\\Rightarrow\E_a=22878.033\ J/mol=22.78 KJ /mol[/tex]

Hence, the activation energy for this reaction =22.78KJ/ mol

Explanation:

In the reaction of magnesium with hydrochloric acid magnesium chloride and hydrogen gas is formed.

Equation -

Mg + 2HCl → MgCl₂ + H₂↑

Therefore,

Option A is correct ✔.

Answer:

Its A

Explanation: Just took the Pre-Unit test

Answer:

Element is not present in an atom

Answer:

element

Explanation:

Answer:

Explanation:

When the primary amine undergoes Hofmann degradation it forms an Alkene

In this case the alkenes have undergone ozonolysis and has formed two products as butanal and 2-methyl propanal

when we revert back from these aldehydes to alkene we observed the alkene formed will be "2-methyl hept-3-ene " this alkene is the Hofmann product of that primary amine

upon addition of this alkene we observe the primary amine formed is

4-amino-2-methylheptane

Answer:

2.9 g

Explanation:

The computation of the mass of oxygen gas produced is shown below:

As we know that

[tex]2NH_4ClO_4 \rightarrow N_2 + Cl_2 + 2O_2 + 4H_2O[/tex]

Now

The [tex]NH_4ClO_4[/tex] presented in 9.6g = 9.6 g/117.49 g/mol  

And, the mole ratio between the [tex]NH_4ClO_4 : H_2O[/tex] is 1 : 2

The moles of [tex]H_2O[/tex] produced is 2 × 9.6 g/117.49 g/mol

So,

Mass of H2O produced is

= 18.015 g/mol × 2 × 9.6 g/117.49 g/mol

= 2.94 g

Answer:

3

Explanation:

I have indeed already took the quizzes my friend

Answer:

Explanation:

The Chromite ore is used for the production of Chromate/dichromate formation.

[tex]4FeCr2O4 + 8Na2CrO4+7O2 \\[/tex] →[tex]8NaCrO4 +2Fe2O3 +8CO2\\yellow[/tex]

so[tex]Na2CrO4[/tex] is called Chromite ore which is of yellow color.

[tex]Na2CrO4 +2H^+[/tex] → [tex]Na2CrO4 +2Na^+ +H2O[/tex]

                                [tex]Orange[/tex]

so when sodium chromate is reacted with hydrogen ion it forms sodium dichromate which is of orange color

Now

[tex]Na2Cr2O7+2KCl[/tex]→[tex]K2Cr2O7 + NaCl[/tex]

The chromate and dichromate are interconvertible in aqueous solution depending upon the PH of solution

Acid medium: [tex]Cr2O4^2-[/tex] [tex]2H^+[/tex]→[tex]Cr2O7^2-[/tex][tex]+H2O[/tex]

Base:[tex]Cr2O7^2- +2OH^-[/tex]→  [tex]CrO4^2- +H2O[/tex]

Hence Chromate and dichromate are interconvertible and hold and equilibrium.

Answer:

V = 83.6 L

Explanation:

Given data:

Number of moles of He = 5.33 mol

Pressure of gas = 1.56 atm

Temperature of gas = 25°C

Volume of sample = ?

Solution:

Formula:

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

Now we will convert the temperature.

25+273 = 298 K

Now we will put the values in formula.

1.56 atm × V = 5.33 mol ×  0.0821 atm.L/ mol.K  × 298 K

1.56 atm × V = 130.4 atm.L

V = 130.4 atm.L/1.56 atm

V = 83.6 L

Answer:

Q = 10118.4 j

Explanation:

Given data:

Mass of ice = 30.0 g

Initial temperature of ice = -20°C

Final temperature = 140°C

Energy required = ?

Solution:

The specific heat of ice is 2.108 J/g*°C

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 140°C -  (-20°C)

ΔT = 160°C

Q = 30.0 g× 2.108 J/g°C ×160°C

Q = 10118.4 j

Answer:

62.6 %

Explanation:

Pb(NO₃)₂  = 207 + 124 = 331 gram

331 gram of lead nitrate contains 207 grams of lead

100 gram of lead nitrate contains

207 x 100 / 331  = 62.6 %

It can be deduced that percentage by mass of lead in Pb(NO₃)₂ is B. 62.6%.

From the given information, Pb(NO₃)₂ = 207 + 124 = 331 grams.

Therefore, 331 gram of lead nitrate contains 207 grams of lead. It can be deduced that 100 gram of lead nitrate will contain:

= 207 x 100 / 331

= 62.6 %

In conclusion, the correct option is 62.6%.

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Answer:

See full explanation.

Explanation:

Hello.

In this case, since we apply the law of mass action in order to write the equilibrium expression for each chemical reaction, we proceed as follows:

a. The reaction is:

[tex]2COF_2(g)\rightleftharpoons CO_2(g)+CF_4(g)[/tex]

And the equilibrium expression:

[tex]Kc=\frac{[CO_2][CF_4]}{[COF_2]^2}[/tex]

Since all the species are in gaseous phase they are included on the equilibrium expression.

b. The reaction is:

[tex]Cu(s)+Ag^+(aq)\rightleftharpoons Ag(s)+Cu^{2+}(aq)[/tex]

And the equilibrium expression:

[tex]Kc=\frac{Cu^{2+}}{Ag^+}[/tex]

Since only copper (II) ions and silver (I) ions are in aqueous phase.

c. The reaction is redox and it turns out:

[tex](S_2O_8)^{2-}+Fe^{2+}\rightleftharpoons Fe^{3+}+(SO_4)^{2-}\\\\S_2^{7+}+2e^-\rightarrow 2S^{6+}\\\\2\times (Fe^{2+}\rightarrow Fe^{3+}+1e^-)\\\\\\(S_2O_8)^{2-}(aq)+2Fe^{2+}(aq)\rightleftharpoons 2Fe^{3+}(aq)+2(SO_4)^{2-}(aq)[/tex]

And the equilibrium expression:

[tex]Kc=\frac{[Fe^{3+}]^2[(SO_4)^{2-}]^2}{[(S_2O_8)^{2-}][Fe^{2+}]^2}[/tex]

Since all the species are in aqueous phase.

Answer:

The shape around the carbon is linear . Sp hybridisation generally tends to be linear.

Explanation:

The hybridization procedure includes blending of the valence s orbital with one of the valence p orbitals to yield equal sp hybrid orbitals which can be orientated in a linear geometry. The p orbital is one orbital that could keep up to 2 electrons. The sp set is equal orbitals that factor 180° from every other.

Hence , the answer is linear shape around the carbon.

Answer:

A Weak acid indicator has general formulae HIn- and base has In-.

When constructed a plot determining wavelength equilibrium reached according to the equation HIn(aq) + H2O(l) ↔ In-(aq) + H3O+(aq)

HIn(aq) is the acid, that has a different color from the base In-(aq). When the pH is low, the concentration of the hydronium ion H3O+ is high and equilibrium is toward the left, producing the color A.

At high pH, the concentration of H3O+ is low, so equilibrium tends toward the right side of the equation and color B is displayed

Answer:

4

Explanation:

H2S(g) + O2(g) → S8(l) + H2O(g)

Upon balancing the equation;

8H2S(g) + 4O2(g) → S8(l) + 8H2O(g)

The coefficient of O2 in the reaction above is 4.

Answer: Option 2, The ability to do work.

Explanation: Edge

Energy can be defined as:

B. the ability to do work, It can of many forms.

Energy is the capacity of an item to take care of business. It might exist in potential, motor, warm, electrical, substance, atomic, or other different structures. As per the work-energy hypothesis, the work done is put away in the energy of the body.

Thus, option B is correct.

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Answer:

A is the correct answer

Explanation:

Answer:   Bonds form when atoms share or transfer valence electrons. Valence electrons are the electrons in the outer energy level of an atom that may be involved in chemical interactions. Valence electrons are the basis of all chemical bonds.

Explanation: Due to atoms and science ;)

Answer:

throught transferring or sharing an electron

Explanation:

a p e x :)))

Answer:

Empirical formula: C3H30

Molecular formula: C6H6O2

Explanation:

The empirical formula can be calculated thus:

65.45% C - 65.45g

5.45% H - 5.45g

29.09% O - 29.09g

We convert each mass to mole by dividing by their respective atomic mass:

C = 65.45/12 = 5.45mol

H = 5.45/1 = 5.45mol

O =29.09/16 = 1.82mol

Next, we divide each mole value by the smallest value;

C = 5.45mol/1.82 = 2.99

H = 5.45mol/1.82 = 2.99

O = 1.82mol/1.82 = 1

Approximately, the empirical ratio of C, H and O is 3:3:1 i.e. C3H3O

Molecular formula is calculated thus:

(C3H3O)n = 100g/mol

{12(3) + 1(3) + 16}n = 100

(36+3+16)n = 100

(55)n = 100

n = 100/55

n = 1.82

n = 2

Molecular formula= (C3H3O)2

C6H6O2

Answer Copper, copper is a type of metal, so it can form cations

The atoms of element will form cations is Copper as to get the stable electronic configuration.

Cations are those species which carries possitive charge on it and produced by any element by lossing of their outermost electrons.

An atom will form cation to get the stable outermost configuration.

Hence option (C) is correct i.e. Copper.

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Answer:

Explanation:

 pH = 5.7

- log [ H⁺ ] = 5.7

[ H⁻ ] = 10⁻⁵°⁷ M

= 2 x 10⁻⁶ M

[ H⁺ ] x [ OH⁻ ] = 10⁻¹⁴

2  x 10⁻⁶ x [ OH⁻ ] = 10⁻¹⁴

[ OH⁻ ] = .5 x 10⁻⁸ M

= 5 x 10⁻⁹ M

Answer:

Explanation:

Molecular reaction

Zn + Cu( NO₃ )₂ = Zn( NO₃ )₂ + Cu

Complete reaction

Zn + Cu⁺² + 2 NO₃⁻ =  2 Zn⁺² + 2 NO₃⁻ + Cu

net ionic reaction

Zn + Cu⁺² = Zn⁺² + Cu