What does a negative A Hf for a molecule mean?​

Answer:

True True False

Explanation:

Explanation:

Models do not behave exactly like the things they represent. Accuracy—In order to make models simplistic enough to communicate ideas some accuracy is lost. For example, ball and stick models of atoms do not show all the details that scientists know about the structure of the atom.

Modeling Benefits

Viewing systems from multiple perspectives.

Discovering causes and effects using model traceability.

Improving system understanding through visual analysis.

Discovering errors earlier and reducing system defects.

Exploring alternatives earlier in the system lifecycle.

Explanation:

when the water evaporates the substance is left behind

Answer:

jsiei6usjdmcicmsicokfjck jsjdndjksk

Explanation:

gshsjsjjdnbshd had 3the 3most 3PM and humiliatin to get 3rid 3in the body 3to 33and to remove

Answer:

"A"

Explanation:

The magnetic dipole axis of the earth is tilted about 11½° from the rotation axis. This means the magnetic north pole and the geographic north pole are not in the same place. ...

They are also not the sam ehtings :

Magnetic axis is the straight line joining the two poles of a magnet (as the magnetic poles of the earth)

Rotational axis i think is the straight line that joines the north and the south pole of the  .earth .... NOTE: The earth is a bit tilted....

look at the daigram for reference.

The rotational axis of the Earth and its magnetic axis are separated by 11.5 degrees and are not one and the same.

The rotational axis is an imaginary line or axis through which any object rotates and revolves.

The angular momentum vector of the object is divided by the angular momentum magnitude to find the rotational axis of an object.

The rotational axis of the earth is 23.5 degrees.

Thus, the correct option is A.

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Answer:

Explanation:

The pH of a solution can be found by using the formula

[tex]pH = - log ([ {H}^{+} ])[/tex]

From the question we have

[tex]pH = - log(3.33 \times {10}^{ - 7} ) \\ = 6.477555...[/tex]

We have the final answer as

Hope this helps you

Answer:

a. 2HCl + 1Mg(OH)2 → 1MgCl2 + 2H2O

b. 1 mol MgCl2/ 1 mol Mg(OH)2

1 mol MgCl2/ 2 mol HCI

Explanation:

a. The reaction of an acid (HCl) with a base (Mg(OH)2) produce water (H2O) and the salt (MgCl2):

_HCl + _Mg(OH)2 → _MgCl2 + _H2O

To balance the Cl:

2HCl + _Mg(OH)2 → _MgCl2 + _H2O

To balance the oxygen:

2HCl + _Mg(OH)2 → _MgCl2 + 2H2O

The reaction is now balanced

2HCl + 1Mg(OH)2 → 1MgCl2 + 2H2O

b. Based on the balanced reaction, the moles ratios are:

1 mol MgCl2/ 1 mol Mg(OH)2

1 mol MgCl2/ 2 mol HCI

Answer:

Tsunami wave

Explanation:

lol 100% sure

Answer: An endothermic reaction occurred

Explanation:

A sample of a compound is added to distilled water in a clean beaker. A reaction occurs and the water temperature drops rapidly which indicates that an endothermic reaction occurred. Hence, option A is correct.

Endothermic reactions are chemical reactions in which the reactants absorb heat energy from the surroundings to form products.

An endothermic reaction means that heat is absorbed during this reaction (enthalpy change value has a positive sign).

During the endothermic reaction heat is absorbed from the surroundings (here, water) and hence the temperature of the water in which the reaction is taking place decreases.

Hence, option A is correct.

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Answer:

It is given that the mass of a man is 75 Kg in earth. Then his mass would be same in moon as mass of anything cannot be changed. The weight of the man in earth can be calculated by W=mg=75×9.8=735 N.

Answer:

[tex]\boxed {\boxed {\sf 4.8 \ M \ KCl}}[/tex]

Explanation:

The molarity of a solution is found by dividing the moles of solute by the liters. of solvent.

[tex]molarity=\frac{moles}{liters}[/tex]

We know the solution has 3.6 moles of potassium chlorine. We know there are 750 milliliters of solvent, but we need to convert this to liters.

Now we know the moles and liters, so we can calculate molarity.

Substitute these values into the formula.

[tex]molarity= \frac{3.6 \ mol \ KCl}{0.75 \ L}[/tex]

Divide.

[tex]molarity= 4.8 \ mol \ KCl/ L[/tex]

[tex]molarity= 4.8 \ M \ KCl[/tex]

The molarity of the solution is 4.8 M KCl.

Answer:

Explained below

Explanation:

First of all we need to know that diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration.

Now, the meaning of a substance having higher concentration or lower concentration is that the amount of solute of a given concentration is higher in the higher concentration region than that in the region of lower concentration.

Answer:

NH3 + H2O → NH4+ + OH-

Explanation:

Ammonia, NH3 can act as a base in water (H2O), which serves as the acid, as follows;

NH3 (aq) + H2O (l) → NH4OH (aq)

According to Bronsted–Lowry acid–base theory, NH4+ (ammonium) is the conjugate acid because it can lose hydrogen ion to form the base while OH- is the conjugate base because it can gain hydrogen ion to form the acid. The balanced ionic equation is as follows;

NH3 + H2O → NH4+ (aq) + OH- (aq)

Answer:

V2 = 90.7 mL

Explanation:

pressure and volume are inversely proportional, if the pressure is increased, the volume will decrease. In an isothermal process:

p1V1 = p2V2

V2 = p1V1/p2 = (277 torr×187 mL)/571 torr

V2 = 90.7 mL

Answer:

0.48 mols

Explanation:

to convert moles to mass u need to divide mass by the molar mass of NaCl which is 58.44g/mols.

28g ÷ 58.44g/mol = 0.48 mols

Answer:

0.01 mole

Explanation:

Answer:

A biotic factor is a living organism that shapes its environment. In a freshwater ecosystem, examples might include aquatic plants, fish, amphibians, and algae. Biotic and abiotic factors work together to create a unique ecosystem.

Answer:

A FWOGGY!

Explanation:

hey mid! how ya doin?

Answer:

The answer is B

Explanation:

Carbon dioxide is a chemical compound that consists of two oxygen atoms and one carbon atom. Carbon Dioxide (CO2) is a gas with a molecular structure composed of two oxygen atoms and one carbon atom.

Hope this helps!

Answer:

31.08 atm.

Explanation:

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

Initial volume (V₁) = 0.60 L

Initial temperature (T₁) = 161 K

Final volume (V₂) = 14.1 L

Final temperature (T₂) = 297 K

Final pressure (P₂) = 2.44 atm

Initial pressure (P₁) =?

The initial pressure of the gas can be obtained as follow:

P₁V₁/T₁ = P₂V₂/T₂

P₁ × 0.6 / 161 = 2.44 × 14.1 / 297

P₁ × 0.6 / 161 = 34.404 / 297

Cross multiply

P₁ × 0.6 × 297 = 161 × 34.404

P₁ × 178.2 = 5539.044

Divide both side by 178.2

P₁ = 5539.044 / 178.2

P₁ = 31.08 atm

Thus, the initial pressure of the gas was 31.08 atm.

Answer:

Spectroscopy — the study of the absorption and emission of light by atoms

Absorption spectrum — represents energy absorbed as dark bands

Atomic spectrum — represents energy emitted or absorbed

during electron jumps

Emission spectrum — represents energy emitted as colored lines

Explanation:

Spectroscopy is an analytical technique to study and analyze using spectrum. It has been the absorption and emission of other light by the atoms. The correct matches are A.1, B. 2, C.3, and D.4.

Spectroscopy is the technique used in chemistry where matter absorbs and emits radiations of a certain wavelength. The absorption spectrum is used to represent absorbed energy in the form of dark bands or lines. Thus, options A.1 and B.2 are correct.

The atomic spectrum is characterized by the black-colored bands that depict the energy absorbed and emitted by an excited atom during electron transitions. Whereas, the emission spectrum shows the colored lines that is the energy emitted when an electron transits from higher to lower energy levels. Thus, options C.3 and D.4 are correct.

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Answer:

ionic compounds are made from metal and non mental elements

Explanation:

in this case it is know as an ionic compound because it contains a charge. For example, NaCl is simply a compound as it contains no charges (the charges cancel out as Cl is -1 and Na is +1)

but OH- is an ionic compound as it has a charge if -1 (O has a -2 charge and H has a +1 charge, so -2+1=-1 so OH has -1 charge)

Reason:- The Mechanism of Diffusion In the case of food coloring in water, the water is the solvent while the food coloring is the solute. Once they've mixed, they make a solution. Diffusion takes time, though how much time depends on the kinetic energy of the molecules randomly bouncing among each other.

Answer:

Red

Explanation:

Answer:

6 mass

Explanation:

because the si unit of gram is mass

Answer:

Carbon dioxide is held together by weak intermolecular forces (only London dispersion LD) and is a non-polar molecule. Because of this weak attraction, it exists as a gas. Water on the other hand is polar (dipole forces DP), and has a stronger hydrogen bond existing within it (in addition to LD). This makes it attract itself more than say carbon dioxide molecules, so it commonly exists as a liquid. Finally, salt like water is polar, and has ionic bonds that are even stronger than a hydrogen bond. This makes salt have a great attraction to itself, sticking together as a solid because its molecules cant easily be broken up.

Explanation:

These are the strongest intermolecular forces ranked from strongest to weakest.

1. Network Covalent

2. Ionic

3. Hydrogen Bonding

4. Dipole Dipole

5. London Dispersion

Answer: Hello, There! your answer is Below.

D. The formation of a solid from a liquid confirms that a physical

change took place.

Explanation:

The change from the liquid state to the solid state is called freezing. As the liquid cools, it loses thermal energy. As a result, its particles slow down and come closer together. Attractive forces begin to trap particles, and the crystals of a solid begin to form.

Hope this helps you!!!

Have a great day!!!

When a liquid undergoes solidification and change of phase it is called freezing. The physical change can be confirmed by changes in the state of matter from liquid to solid. Thus, option D is correct.

Physical changes are the modification in the matter or object that can be reversed back to its original state. They do not produce substances that are irreversible.

The change of the phase of the matter from liquid to solid when water substance undergoes freezing is a physical change as no new compound is created and the solidified substance can get converted back to liquid.

Therefore, option D. solid from liquid shows a physical change.

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Answer:

Why hydrogen is the only non-metal elements which loses electron to form positive ions ? ... When hydrogen bonded with most electronegative element then it forms a positive ions but when it bonded with less electronegative element then it forms a negative ion.

Answer:

500.00

Explanation:

400+20+50+49+17+59

Answer:

D. The resulting solution does not conduct electricity.

Explanation:

Hello there!

In this case, for the given chemical reaction we can say that:

A. it is true because the nitric acid ionizes into hydrogen and nitrate ions

B. it is a decomposition reaction because the acid is partitioned into the composing ions.

C. it is ionized to hydrogen cations and nitrate anions.

D. this is incorrect because nitric acid is a strong electrolyte able to conduct the electricity.

Regards!