Which of the following statements about semi-empirical methods are true?
a. It combines a theoretically sound model of bonding with some experimentally determined parameters.
b. It is faster to calculate than ab initio methods.
c. It can determine precisely both the location and the energy of bonding electrons.
d. It treats bonds simply as springs.

Answer:

The growth of any plant is controlled by many factor and it depends on them.

Explanation:

The words are sorted according to their genetic factors and the environment factors by the category on which they effect and impact the growth of a plant.

Genetic factor :

Waxy leaves, bad tasting leaves, disease, leaf structure, types of stem, plant structure, reproduction, types of roots.

Environment factor : sunlight, drought, fire, flood, heat wave, insects, wind, space, pH of soil, temperature, pollution, terrain, soil conditions, lack of air.

Answer: The Law of Conservation of Mass dates from Antoine Lavoisier's 1789 discovery that mass is neither created nor destroyed in chemical reactions. In other words, the mass of any one element at the beginning of a reaction will equal the mass of that element at the end of the reaction.

Explanation:

Answer:

1. I

2.LOVE

3.YOU

JUST KIDDING

REAL ANSWER

Therefore, to get a neutral compound requires two Br and one Ca - ie, CaBr2.

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Answer:

6.48%

Explanation:

Answer:

[tex]d=4.75\times 10^{-9}\ \text{inches}[/tex]

Explanation:

Given that,

The distance between the centers of the two oxygen atoms in an oxygen molecule is [tex]1.21\times 10^{-8}\ cm[/tex].

We need to convert this distance in inches.

We know that,

1 cm = 0.393 inches

We can solve it as follows :

[tex]1.21\times 10^{-8}\ cm=0.393\times 1.21\times 10^{-8}\\\\=4.75\times 10^{-9}\ \text{inches}[/tex]

So, the distance between the centers of the two oxygen atoms is [tex]4.75\times 10^{-9}\ \text{inches}[/tex].

Answer:

298. 7 K.

Explanation:

Hello!

In this case, since equation we use to compute the heat in a cooling or heating process is:

[tex]Q=mC(T_f-T_i)[/tex]

Whereas we are given the heat, mass, specific heat and initial temperature. Thus, we infer that we need to solve for the final temperature just as shown below:

[tex]T_f=T_i+\frac{Q}{mC}\\\\T_f=1000 K+\frac{-270000J}{1000g*0.385\frac{J}{g*K} } \\\\T_f=298.7 K[/tex]

It is important to notice that the iron release heat as water absorbs it, that is why it is taken negative.

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Answer: 122.9 g

Explanation:  Fe2O3 mw = 160 of which 112 is Fe

to get 86 g Fe, 86*160/112 g oxide

Answer: The average atomic mass  of naturally occurring silicon  is 28.08

Explanation:

Mass of isotope Si-28 = 27.9769265327

% abundance of isotope Si-28 = 92.2297% = [tex]\frac{92.2297}{100}[/tex]

Mass of isotope Si-29 = 28.97649472

% abundance of isotope Si-29 = (4.6932)% = [tex]\frac{4.6832}{100}[/tex]

Mass of isotope Si-30 = 29.97377022

% abundance of isotope Si-30 = (3.0872)% = [tex]\frac{3.0872}{100}[/tex]

Formula used for average atomic mass of an element :

[tex]A=\sum[(27.9769265327\times \frac{92.2297}{100})+(28.97649472\times \frac{4.6832}{100})+(29.97377022\times \frac{3.0872}{100})][/tex]

[tex]A=28.08[/tex]

Therefore, the average atomic mass  of naturally occurring silicon  is 28.08

Answer:

D. 77.0%

Explanation:

% yield = actual yield/theoretical yield x 100%

% yield = 1.57 g / 2.04 g x 100%

% yield = 76.96 (round up)

Moles of Fe produced = 40 moles

Given

Reaction

2Fe2O3 + 3C —— 4Fe + 3C02

20 moles of C

Required

moles of Fe

Solution

The reaction coefficient in a chemical equation shows the mole ratio of the reacting compounds (reactants and products)

From the reaction, mol ratio of Fe : C = 4 : 3, so mol Fe :

= 4/2 x mol C

= 4/2 x 20

= 40 moles

Answer:C10H12

Explanation:

Given :empirical formula =C5H6

molar mass of carbon =12 g /mole approximately

molar mass of hydrogen =1.01g/mole approximately

molar mass of C5H6=(5*12)+(6*1.01)=66.06 g/moles

132.21/66.06=2 approximately

therefore ,the answer is  C10H12

I HOPE IT HELPS !!

Answer:31 days

Explanation:

3500kcal/lb x 5lb =17500

1800-1230=570

17500/570=30.70

Round up =31

This question involves the concepts of energy, weight, and time.

It will take Charles "9.7 days" to lose 5.0 lb.

Since the loss of 1.0 lb weight requires expending 3500 kcal energy. Therefore, by using the unitary method,

1.0 lb loss = 3500 kcal

(5)(1.0) lb loss = (5)(3500 kcal)

5.0 lb loss = 17500 kcal ----- eqn(1)

Now, the time required to consume 1800 kcal is 1 day. Hence, by the unitary method,

1800 kcal = 1 day

1 kcal = [tex]\frac{1}{1800}\ day[/tex]

17500 kcal = [tex]\frac{17500}{1800}[/tex] day

17500 kcal = 9.7 days ------ eqn(2)

Comparing eqn (1) and eqn (2)

5.0 lb loss = 9.7 days

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Answer:

Formula for aluminum oxide Al₂O₃

Explanation:

Hope that helps

Answer:

Al2O3, ionic

Explanation:

Answer:

[tex]7.84\ \text{moles}[/tex]

Explanation:

Number of atoms of carbon = [tex]4.72\times 10^{24}[/tex]

Avogadro's number = [tex]6.022\times 10^{23}\ \text{mol}^{-1}[/tex]

Here we have to divide the number of atoms by the Avogadro's number

[tex]\dfrac{4.72\times 10^{24}}{6.022\times 10^{23}}=7.83792\approx 7.84\ \text{moles}[/tex]

The moles of carbon are [tex]7.84\ \text{moles}[/tex].

Answer:

1. Mn(s) + Ca(NO₃)₂(aq)  ----> No reaction

2. KOH(aq) +  Fe(s)   ----> No reaction

3. Pt(NO₃)₂(aq) + Cu(s)  ----> Reaction occurs

4. Cr(s) + H₂SO₄(aq)   ----> Reaction occurs

Explanation:

The activity series of metals is a series that arranges metals in order of reactivity from highest to lowest. It is used to determine which metal will displace another in a single displacement reactions, whereby a metal A, will replace or be replaced by another metal B in an aqueous solution depending on their relative positions in the activity series.

Considering the given reactions:

1. Mn(s) + Ca(NO₃)₂(aq)

2. KOH(aq) +  Fe(s)

3. Pt(NO₃)₂(aq) + Cu(s)

4. Cr(s) + H₂SO₄(aq)

Reaction 1 will not occur because manganese, Mn, is lower than calcium, Ca, in the activity series of metals and cannot displace it from aqueous solutions.

Reaction 2 will not occur since iron, Fe, is lower than potassium, K, in the activity series and cannot displace it from aqueous solutions.

Reaction 3 will occur since platinum, Pt, is lower than copper, Cu, in the activity series and thus can be displaced by copper from aqueous solutions.

Reaction 4 will  occur since chromium, Cr, is higher than hydrogen, H, in the activity series and thus, can displace it from aqueous solutions.

Answer:

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Answer:

P₂O₄

Explanation:

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

Empirical formula = PO₂

Molar mass of compound = 126 g/mol

Molecular formula =.?

The molecular formula of the compound can be obtained as illustrated below:

Molecular formula = [Empirical]ₙ

= molar mass

[PO₂] × n = 126

[31 + (16× 2)] × n = 126

[31 + 32] × n = 126

63 × n = 126

Divide both side by 63

n = 126 / 63

n = 2

Molecular formula = [PO₂]ₙ

Molecular formula = [PO₂]₂

Molecular formula = P₂O₄

Answer:

Z = 1 - a/VRT

Explanation:

Note :

Compressibility Factor, Z = PV / RT

Vander waal forces at Lower pressure is represented by the expression :

V[P + a/V²] = RT

Aim is to move PV /RT =Z to one side of the equation.

Using change of subject :

opening the bracket :

PV + aV / V² = RT

PV + a/V = RT

Divide through by RT

PV/RT + a/VRT = RT/RT

PV/RT + a/VRT = 1

Recall:

PV /RT = Z

equation becomes :

Z + a/VRT = 1

Subtract a/VRT from both sides

Z + a/VRT - a/VRT = 1 - a/VRT

Z = 1 - a/VRT

Answer:

2.68 cm^3

Explanation:

Density= Mass/Volume

so...

8.96 g/cm^3 = 24.01 g/ V

and then u solve so it would be 2.68 cm ^3

((:

Answer:

it is option c. the mass is equal of both

The law of conservation of mass is the concept used here to find out the true statement. The correct option is C - The mass of the products is equal to the mass of the reactants.

The law which states that matter can neither be created nor destroyed in a chemical reaction is defined as the law of conservation of mass. This law was postulated by the scientist A. Lavoisier.

This law also states that the total mass of the products should be always equal to the total mass of the reactants. The reactants are the substances which are seen on the left part of the equation and the products are seen on the right part of the equation.

Here the mass of the compound Mercury (II) oxide is same as that of mercury and oxygen. Thus the given equation obeys the law of conservation of mass.

Thus the correct option is C.

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Answer: balanced

Explanation:

Answer:

Kp = Kc (RT) ^(-2)

Explanation:

For the reaction;

N2 (g) + 3H2 ⇄ 2NH3(g)

We can write;

Kc = [NH3]^2/[N2] [H2]^3

But

Kp = pNH3^2/pN2 . PH2^3

To convert from Kc to Kp

Kp = Kc (RT) ^Δn

where Δn is the change in number of moles going from reactants

to products.

For this reaction;

Δn = 2- (3+1) = -2

Kp = Kc (RT) ^(-2)

Answer:

Dispersion forces

Dipole-Dipole interaction

Explanation:

The London dispersion force refers to the temporary attractive force that acts between the electrons in two adjacent atoms when the atoms develop temporary dipoles. Dispersion forces act between any two molecules even when other intermolecular forces are in operation as long as the molecules are in close proximity to each other.

Now, CO is polar and the HCN is also polar molecule. Hence, dipole - dipole interaction forces  are also in operation and acts between the two molecules in close proximity to each other.

Dispersion forces and Dipole-Dipole interaction are intermolecular forces which act between a hydrogen cyanide (HCN) molecule and a carbon monoxide molecule

The transitory attractive force that exists between the electrons in two nearby atoms when the atoms form transient dipoles is known as the London dispersion force. As long as the molecules are close to one another, dispersion forces can exist between any two molecules, even when other intermolecular forces are active.

The HCN molecule and CO are both polar molecules right now. As a result, dipole-dipole interaction forces act between the two molecules when they are close to one another.

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3.0 × 10²³ molecules AgNO₃

Math

Pre-Algebra

Order of Operations: BPEMDAS

Chemistry

Atomic Structure

Stoichiometry

Step 1: Define

85 g AgNO₃ (silver nitrate)

Step 2: Identify Conversions

Avogadro's Number

[PT] Molar Mass of Ag - 107.87 g/mol

[PT] Molar Mass of N - 14.01 g/mol

[PT] Molar Mass of O - 16.00 g/mol

Molar Mass of AgNO₃ - 107.87 + 14.01 + 3(16.00) = 169.88 g/mol

Step 3: Convert

Step 4: Check

Follow sig fig rules and round. We are given 2 sig figs.

3.01313 × 10²³ molecules AgNO₃ ≈ 3.0 × 10²³ molecules AgNO₃

Answer:

Convention

Explanation:

Answer:

Because the soup became warm and less dense, so it rose up.

Explanation:

Found on Course Hero is an American education technology website company based in Redwood City, California, which operates an online learning platform for students to access course-specific study resources contributed by a community of students and educators.

Answer:

Part 1

triple point; 0.72 atm, 115.8 K

Part 2

Option D, The sample is initially a gas.

Explanation:

Part 1

The triple point of krypton is  0.72 atm

and the melting point of Krypton is -157.4 °C or  115.8 K

Hence, option C is correct

Part 2

Option D

At 59.8 atm, Krypton is a gas. It changes its state from gas to liquid and solid when the temperature is extremely low. Here the temperature is same , hence only option D is correct