Help please :) I don’t understand

Answer:

27.8

Explanation:

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Answer:

Learning the rock cycle and understanding the processes involved helps all of us. This is how soil forms, through the breakdown of rocks. We need soil to survive—imagine trying to grow vegetables without it. This is an immediate connection to the food chain

Answer:

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Answer:

O2 is the answer I believe

Answer: D

Explanation:

Answer:

The answer is "4.31"

Explanation:

aniline millimoles [tex]= 111 \times 0.37 = 41.07[/tex]

added [tex]HNO_3[/tex]  millimoles [tex]= 79.1 \times 0.35 = 27.685[/tex]

[tex]\to 41.07 - 27.685 = 13.385[/tex] millimoles aniline left

[tex]\to 27.685[/tex] millimoles salt formed

total volume[tex]= 111 + 79.1 = 190.1\ mL\\\\[/tex]

[tex]\to [aniline] = \frac{13.385}{190.1} = 0.07 \ M\\\\\to [salt] =\frac{ 27.685}{ 190.1} = 0.146\ M\\\\\to pOH = pKb + \frac{\log [salt]}{ [base]}\\\\\to pOH = 9.37 + \frac{\log [0.146]}{[0.07]}\\\\\to pOH = 9.69\\\\\to pH = 14 - 9.69\\\\\to pH = 4.31\\[/tex]

Answer:

true

Explanation:

This layer will prevent moisture from reaching the metal and therefore prevent rust. oil paint especially

Answer: Al₂O₃

Explanation:

Answer:

12.8

Explanation:

14 = pOH + pH

pH = 14 - pOH

pH = 14 - 1.2

pH = 12.8

Answer:

SnSO₄

Explanation:

Tin(II) sulfate is a chemical compound. It is a white solid that can absorb enough moisture from the air to become fully dissolved, forming an aqueous solution; this property is known as deliquescence.

Answer:

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Explanation:

SnSO₄

Answer: hcl

Explanation:

Answer:

Option D. The number of oxygen atom is the same before and after the reaction.

Explanation:

From the question given above, the following were obtained:

Robin's equation:

H₂ + O₂ —> H₂O

Alex's equation

2H₂ + O₂ —> 2H₂O

To know which equation better represents the reaction, we shall determine which of the equation is balanced.

For Robin:

H₂ + O₂ —> H₂O

Element >>> Reactant >>> Product

H >>>>>>>>> 2 >>>>>>>>>> 2

O >>>>>>>>> 2 >>>>>>>>>> 1

Robin's equation is not balanced because the number of atoms of each element in the reactant and product are not equal.

For Alex:

2H₂ + O₂ —> 2H₂O

Element >>> Reactant >>> Product

H >>>>>>>>> 4 >>>>>>>>>> 4

O >>>>>>>>> 2 >>>>>>>>>> 2

Alex' equation is balanced because the number of atoms of each element in the reactant and product are equal.

Thus, option D gives the right answer to the question.

Answer:

C. II, III, IV, and V.

Explanation:

Acid buffer is  generally formed by the combination of a weak acid as well as the salt of the conjugate base.

Basic buffer is formed the combination of a weak base and also the salt of the conjugate acid.

On dilution the ration of the concentration terms of the salt and weak acid/base does not change. Hence the pH of the buffer solution does not change.

When acid or base is added to buffer, it resists changes in the pH.

Therefore, option (C) is correct.

Answer:

See Explanation

Explanation:

The unbalanced reaction equation is;

CO2(g) + LiOH(aq) + Li2CO3(aq) + H2O(l)

The balanced chemical reaction equation;

CO2(g) + 2LiOH(aq) + Li2CO3(aq) + H2O(l)

The molar mass of each compound is the sum of the relative atomic masses of the atoms of the elements that compose the compounds.

For CO2

12 + 16(2) = 12 + 32 = 44 g/mol

For LiOH

7 + 16 + 1 = 24 g/mol

For Li2CO3

2(7) + 12 + 3(16) = 74 g/mol

For H2O

2(1) + 16 = 18 g/mol

From the balanced chemical reaction equation, the mole ratio is 1:2:1:1. This is obtained from the stoichiometric coefficient of each reactant in the balanced chemical reaction equation.

From the question;

1 mole of CO2 occupies 22.4 L

x moles of CO2 occupies 825 L

x = 1 mole * 825 L/22.4 L

x = 36.8 moles

From the reaction equation;

1 mole of CO2 produces 1 mole of water

36.8 moles of CO2 produces 36.8 moles of water

Mass of 36.8 moles of water = 36.8 moles * 18 g/mol

= 662 g of water

The answer must have three significant figures because that is the same number of significant figures to which values were given in the question.

Answer:

Extending DNA strands to match samples

[tex]M_{A}V_{A}=M_{B}V_{B}\\(5.25)M_{A}=(4.96)(0.9845)\\M_{A}=\frac{(4.96)(0.9845)}{5.25} \approx \boxed{0.93 \text{ M}}[/tex]

The question is incomplete, the complete question is;

When a lead acid car battery is recharged by the alternator, it acts essentially as an electrolytic cell in which solid lead(II) sulfate PbSO₄ is reduced to lead at the cathode and oxidized to solid lead(II) oxide PbO at the anode.

Suppose a current of 96.0 A is fed into a car battery for 37.0 seconds. Calculate the mass of lead deposited on the cathode of the battery. Round your answer to 3 significant digits. Also, be sure your answer contains a unit symbol.

Answer:

3.81 g of lead

Explanation:

The equation of the reaction is;

Pb^2+(aq) + 2e ---->Pb(s)

Quantity of charge = 96.0 A * 37.0 seconds = 3552 C

Now we have that 1F = 96500 C so;

207 g of lead is deposited by 2 * 96500 C

x g of lead is deposited by 3552 C

x = 207 *  3552/2 * 96500

x = 735264/193000

x = 3.81 g of lead

Answer:

1. Cr₂O₇²−(aq) + 14H+ (aq) + 6e- ---->⟶2 Cr³+(aq) + 7H₂O (l)

2. CrO₄²− (aq)⟶+ 4H+ (aq) + 3e- ---> Cr(OH)₄ −(aq)

3. Bi³+ (aq) + 3H₂O (l) ---> BiO₃− (aq) + 6 H+ (aq) + 2 e-

4. CIO −(aq)⟶+ 2H+ (aq) + 2e- ---> Cl −(aq) + H₂O

Explanation:

The given equations are redox reaction equations expressed as as half reactions.

The first step is to identify whether the half-reaction is oxidation reduction.

Then the number of electrons gained or lost are added on the right side of the equation.

Appropriate H+ ions and water molecules are added where necessary since the reaction takes place in acidic environment

The atoms of elements involved in the reaction are balanced by adding the correct coefficients.

1. (acidic) Cr2O7 2−(aq)⟶Cr 3+(aq)

The half-reaction is reduction as the oxidation number of chromium changes from +6 to +3. Two Cr⁶+ ions accepts 3 electrons each to form Cr³+ ions

Cr₂O₇²−(aq) + 6e- ---->⟶2 Cr³+(aq)

Cr₂O₇²−(aq) + 14H+ (aq) + 6e- ---->⟶2 Cr³+(aq) + 7H₂O (l)

2. (acidic) CrO₄²− (aq)⟶---> Cr(OH)₄ −(aq)

The half-reaction is a reduction. One Cr⁶+ accepts 3 electrons to become Cr³+

CrO₄²− (aq)⟶+ 3e- ---> Cr(OH)₄ −(aq)

CrO₄²− (aq)⟶+ 4H+ (aq) + 3e- ---> Cr(OH)₄ −(aq)

3, (acidic) Bi³+ (aq)⟶---> BiO₃− (aq)

The half-reaction is an oxidation. One Bi³+ ion gives up two electrons to become Bi⁵+

Bi³+ (aq)⟶---> BiO₃− (aq) + 2e-

Bi³+ (aq) + 3H₂O (l) ---> BiO₃− (aq) + 6 H+ (aq) + 2 e-

4. (acidic) CIO −(aq)⟶---> Cl −(aq)

The half-reaction is a reduction. One Cl+ ion accepts two electrons to become Cl- ion.

CIO −(aq) + 2e-⟶---> Cl −(aq)

CIO −(aq)⟶+ 2H+ (aq) + 2e- ---> Cl −(aq) + H₂O

Answer:

The volume is 22.66 mL

Explanation:

D = 22.1 g/cm³, M = 523.1 g, V = ? mL

For Volume

Density = Mass ÷ Volume

Volume = Mass ÷ Density

V = M ÷ D

V = 523.1 g ÷ 22.1 g/cm³

V = 23.66 cm³

Now, 1 cm³ = 1 mL

So,

V = 22.66 mL

Thus, The volume is 22.66 mL

-TheUnknownScientist

Answer:

0.22M

Explanation:

We will be using the law of dilutions. We are simply increasing the amount of solvent to create a larger volume of solution.

So: moles before dilution = moles after dilution & [tex]moles_{concentrated} = moles_{dilute}[/tex]. And M = moles/liter of solution, so if we express this as moles = M x [tex]L_{soln}[/tex].

That is how we derive the formula we will be using: [tex]M_{concentrated} * Vol_{conc} = M_{dilute} * Vol_{dilute}[/tex]

or

[tex]M_{1} * Vol_{1} = M_{2} * Vol_{2}[/tex]

Applying this formula to our problem, we can substitute the variables with the given values to find the molarity of the dilute solution.

M1 = 3.5M

V1 = 18.8mL

M2 = ?

V2 = 296.6mL

Equation: (3.5M)(18.8mL) = (296.6mL)(M2)

==> 65.8M*mL = 296.6mL * M2

==> M2 = (65.8 M*mL)/296.6mL

==> M2 = 0.22M

Answer:

167.217g/mol

Explanation:

Formula mass is defined as the mass in grams that a mole of a molecule weighs. To solve the formula mass of ZrF₄ we require the molar mass of Zr and of F (Molar mass Zr: 91.225g/mol; F: 18.998g/mol)

In this molecule, there is 1 mole of Zr and 4 moles of F. The formula mass is:

Zr = 1*91.225g/mol = 91.225g/mol

F = 4*18.998g/mol = 75.992g/mol

Formula mass: 91.225g/mol + 75.992g/mol

D. Radioactive material can leave the patient’s body through saliva, sweat, and urine.

I took the test n got it right ¯\_(ツ)_/¯

Answer:

Please find the solution in the attachment file.

Explanation:

Answer:

the density of the Gas at STP is 0.227 g/L .

Explanation:

This question involves the combined gas law . The equation for the combined gas law

Answer:

(a) The mass of an object remains the same always. It is independent of its location. In this case, an iron nail is ground into powder.

Explanation:

please mark this answer as brainliest

Answer:

2.18 mol Ar.

Explanation:

Hello there!

In this case, according to the definition of mole as the amount of particles of a given substance, it is possible to introduce the Avogadro's number to assert that 1 mole of any element contains 6.022x10²³ atoms; thus, the moles of Ar in the given amount of atoms turns out to be:

[tex]1.31x10^{24}Ar atoms*\frac{1molAr}{6.022x10^{23}atoms}\\\\=2.18molAr[/tex]

Best regards!

Answer: a) 525 ml

b) 67.2 ml

Explanation:

Boyle's Law: This law states that pressure is inversely proportional to the volume of the gas at constant temperature and number of moles.

[tex]P\propto \frac{1}{V}[/tex]     (At constant temperature and number of moles)

[tex]P_1V_1=P_2V_2[/tex]  

where,

a) [tex]P_1[/tex] = initial pressure of gas  = 752 mm Hg

[tex]P_2[/tex] = final pressure of gas = 385 mm Hg

[tex]V_1[/tex] = initial volume of gas  = 250 ml

[tex]V_2[/tex] = final volume of gas = ?

[tex]752\times 250=385\times V_2[/tex]  

[tex]V_2=525ml[/tex]

Therefore, the volume at 385 mm Hg is 525 ml.

b) [tex]P_1[/tex] = initial pressure of gas  = 752 mm Hg

[tex]P_2[/tex] = final pressure of gas = 3.68 atm = 2796.8 mm Hg    (760mmHg=1atm)

[tex]V_1[/tex] = initial volume of gas  = 250 ml

[tex]V_2[/tex] = final volume of gas = ?

[tex]752\times 250=2796.8\times V_2[/tex]  

[tex]V_2=67.2ml[/tex]

Therefore, the volume at 3.68 atm is 67.2 ml.

Answer:

1. AgNO₃ (aq) + NaCl (aq) ----> NaNO₃ (aq) + AgCl (s)

2. Li₂SO₄ (aq) + BaCl₂ (aq) ----> 2 LiCl (aq) + BaSO₄ (s)

3. 2 NaOH (aq) + MgCl₂ (aq) ----> 2 NaCl (aq) + Mg(OH)₂ (s)

Explanation:

The reaction involving the mixing of two soluble solutions to produce a precipitate is known as a precipitation reaction.

A precipitation reaction is double-replacement reaction (a reaction that exchanges the cations or the anions of two ionic compounds) in which one product is a solid precipitate.

Precipitation reactions at useful in the identification of various ions present in a solution. In order to predict the reactions that will produce a precipitate, solubility rules as given in the solubility table below can be used.

From the tables, the reactions that will produce a precipitate, as well as their balanced molecular equations are as follows:

1. AgNO₃ (aq) + NaCl (aq) ----> NaNO₃ (aq) + AgCl (s)

2. Li₂SO₄ (aq) + BaCl₂ (aq) ----> 2 LiCl (aq) + BaSO₄ (s)

3. 2 NaOH (aq) + MgCl₂ (aq) ----> 2 NaCl (aq) + Mg(OH)₂ (s)

Answer: The molecular formula will be [tex]C_8N_4H_{10}O_2[/tex]

Explanation:

Mass of C= 49.47 g

Mass of N = 28.85 g

Mass of O = 16.48 g

Mass of H = 5.20 g

Step 1 : convert given masses into moles.

Moles of C =[tex]\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{49.47g}{12g/mole}=4.12moles[/tex]

Moles of N =[tex]\frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{28.85g}{14g/mole}=2.06moles[/tex]

Moles of O =[tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{16.48g}{16g/mole}=1.03moles[/tex]

Moles of H =[tex]\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{5.20g}{1g/mole}=5.20moles[/tex]

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = [tex]\frac{4.12}{1.03}=4[/tex]

For N = [tex]\frac{2.06}{1.03}=2[/tex]

For O =[tex]\frac{1.03}{1.03}=1[/tex]

For H = [tex]\frac{5.20}{1.03}=5[/tex]

The ratio of C : N: O: H = 4: 2: 1: 5

Hence the empirical formula is [tex]C_4N_2OH_5[/tex]

The empirical weight of [tex]C_4N_2OH_5[/tex] = 4(12)+2(14)+1(16)+5(1)= 97 g.

The molecular weight = 194.19 g/mole

Now we have to calculate the molecular formula.

[tex]n=\frac{\text{Molecular weight}}{\text{Equivalent weight}}=\frac{194.19}{97}=2[/tex]

The molecular formula will be = [tex]2\times C_4N_2H_5O=C_8N_4H_{10}O_2[/tex]

Answer:

No comparison => John Dalton did NOT postulate an atomic structure.

Explanation:

Dalton's postulates are based upon generalizations of observable phenomena. Micro structure was not proposed.  The atomic structure that's accepted in the scientific community evolved from conclusions of ...

Thompson's raisen pudding model => electrons suspended in a positive matrix

Rutherford's shell model => dense positive nucleus surrounded by an electron cloud. (No fine structure postulated)

Bohr Concentric Ring Model => electrons orbiting a positive nucleus in discrete  energy levels much like planets orbiting the sun.

Schrodinger - Dirac Quantum Models => electrons occupying specific orbital energy levels as based upon statistical wave mechanics.