Which of the following reactions is endothermic?

H2(g) + ½ O2(g)H2O(g),H = -57.82 kcal
½N2(g) + O2(g) + 8.1 kcalNO2(g)
½ N2(g) + 3/2 H2(g)NH3(g) + 11.0 kcal
C(diamond)+ O2(g)CO2,H = -94.50 kcal

The bond between K⁺ and Cl⁻ ions is an ionic bond

Atoms have different stability. Unstable atomic atoms will try to form stable electron configurations like those of noble gases. Where noble gases have the number of outer electrons 2 or 8

The formation of electron configurations such as noble gases can be done by forming shared ions or electron pairs

Atoms with high ionization energy and atoms that are difficult to draw electrons will form bonds with shared electron pairs (electrons can be from one atom or two atoms attached)

Inform ions, atoms will release or attract electrons

Ion bonds occur because atoms that have low ionization energy (easily release electrons) form a + ion, and these electrons are bound by atoms that have large affinity energy (easily pulling electrons)

Generally, ionic bonds occur in metals and nonmetallic elements. Metal elements have low ionization energy and non-metallic elements have a high electron affinity

In Atoms, to achieve stability, K will release one electron so that it has an electron configuration like noble gas Ar

Electron configuration of K (atomic number 19) and Ar (atomic number 18)

K: 2 8 8 1

Ar: 2 8 8

so that it becomes a K⁺ ion

While the Cl atom will bind one electron, so it has an electron configuration like noble gas Ar

Cl: 2 8 7

Ar: 2 8 8

So that it becomes a Cl⁻ ion

Finally, there will be an attractive attraction between positive and negative ions and KCl is formed

So the bond between K + and Action is an ionic bond

the octet rule

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a noble gas

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ionic bonds and covalent bonds

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Answer : The moles of tin metal produced will be, 0.74 mole

Explanation : Given,

Moles of [tex]SnO_2[/tex] = 0.74 mole

The given balanced chemical reaction is,

[tex]SnO_2+2H_2\rightarrow Sn+2H_2O[/tex]

From the balanced chemical reaction, we conclude that

As, 1 mole of [tex]SnO_2[/tex] react to give 1 mole of Sn

So, 0.74 mole of [tex]SnO_2[/tex] react to give 0.74 mole of Sn

Therefore, the moles of tin metal produced will be, 0.74 mole

The trend in atomic radius as you go down a group on the periodic table is an increase. This is because each successive element adds a new electron shell, meaning the outer electrons are further from the nucleus, and more shielded from the nuclear charge by inner shell electrons.

In the Periodic Table, the atomic radius trend seen as you move down a group (a vertical column) is that the atomic radius increases. This trend is due to the increase in the principal quantum number (n level) causing an increase in the size of the electron cloud around the nucleus, making the atomic radius larger. For example, within the group of alkali metals (Group 1), lithium (Li) at the top has a smaller atomic radius than sodium (Na) below it, which is smaller than potassium (K) beneath it, and so forth.

One reason the atomic radius increases as one goes down a group is that with each successive element, a new electron shell is being added. This means that the outer electrons are located further from the nucleus and more shielded from the nuclear charge by inner shell electrons. The effective nuclear charge experienced by the outermost electrons is therefore less, which means the electrons can reside further from the nucleus, leading to an increase in atomic radius for elements down a group.

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Final answer:

Valence electrons are pivotal in chemical bonding, participating in either sharing (covalent bonding) or transferring (ionic bonding) to achieve stable electronic configurations aimed at fulfilling the octet rule. Electronegativity influences the nature of these bonds, and the valence bond theory explains the formation of stable compounds through energy considerations.

Explanation:

Valence electrons play a crucial role in the formation of compounds from elements. These electrons are located in the atom's outermost shell and are the primary participants in chemical bonding. Elements combine to form compounds by either sharing valence electrons (covalent bonding) or transferring them (ionic bonding) to achieve stable electronic configurations, often aiming for the octet rule, which is a full set of eight valence electrons that provides stability, reminiscent of the noble gases.

Electronegativity significantly influences how these electrons are shared or transferred. Atoms with higher electronegativity tend to attract valence electrons more strongly, leading to polar covalent or ionic bonds depending on the difference in electronegativity between the bonding atoms.

The assumption that accounts for the compressibility of gases is that gases consist of molecules which are relatively far apart, meaning the correct answer is A) 1.

In regards to the compressibility of gases, the relevant kinetic molecular theory assumption is that gases consist of molecules which are relatively far apart. This is captured in assumption 1 provided in the student's question. When the particles are far apart, there is a considerable amount of empty space between them compared to liquids and solids. This space allows gases to be compressed, as-the molecules can be brought closer together without significant repulsive forces coming into play due to the fact that there are no significant intermolecular forces acting over these large distances. Therefore, the correct answer to the question - which assumption accounts for the compressibility of gases as compared to liquids and solids - is A) 1.

Answer: 30.8 g

Explanation:

Answer: The compound represents aluminium iodide is AlI3.

Explanation:

Skepticism is important to the biochemist to critically evaluate and verify the conclusion about the behavior of water molecules near proteins.

Skepticism is important in this scenario because it would help the biochemist to critically evaluate and verify the conclusion that water molecules occur in groups of five in the presence of proteins. By maintaining a skeptical mindset, the biochemist can consider alternative explanations, conduct further experiments, and review existing research to ensure the validity and accuracy of the conclusion. Skepticism plays a crucial role in scientific inquiry and helps to ensure that scientific findings are reliable and trustworthy.

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Answer: Cross breeding

Explanation: Cross breeding can be defined as the method by which two plants can be crossed to produce the desired character and compensate the useless characters shown by the plants individually.

Suppose a plant produces pink flower but small slower and another plant produces white flower but big flower.

If we want big pink colored flower then, these two plants can be crossed among each other so to produce the desired characters and hide the useful characters.

Answer:

A:  Always.

Explanation:

Got it correct on Oddesyware

i would go with C. Al+3

The right answer is N2(g) + 3H2(g) => 2NH3(g).

Ammonia (NH3) is produced by the synthesis of nitrogen (N2) and hydrogen (H2):

N2 + 3 H2 → 2 NH3

During the first half of the 20th century, the NH3-green was produced without CO2 emission at

from hydroelectricity, water, and atmospheric air.

H2 came from the electrolysis of water, the N2 of atmospheric air.

Answer is: van der Waals forces and hydrogen bonds.

Intermolecular forces are the forces between molecules or particles.

There are several types of intermolecular forces: hydrogen bonding, ion-induced dipole forces, ion-dipole forces andvan der Waals forces.

Hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (H), covalently bound to a highly electronegative atom such as flourine (F), oxygen (O) and nitrogen (N) atoms.

Covalent bonds, ionic bonds and metallic bonds are intramolecular interactions, bonds between atoms in molecule.

Answer:

B: When you do not need many details about the experiment

Explanation:

Primary Sources are the first-hand accounts of the topic.

Secondary sources are the scholarly books or articles.

The secondary source interprets and also analyzes the primary sources.

Thus, secondary data can be used as a precursor for publishing new primary data.

Thus, Option B: When you do not need many details about the experiment is correct.

The principle 'like dissolves like' is used to determine the solubility of compounds in CCl₄. These are more likely to dissolve: Br₂ over NaBr, C₆H₁₁OH over CH₃OH, CS₂ over KOH, and I₂ over CaF₂.

The solubility of compounds in CCl₄ can be calculated using the principle 'like dissolves like', which means that substances with similar types of molecular interactions dissolve in each other. Therefore, compounds with similar polarity will dissolve in each other.

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Final answer:

The more soluble compounds in carbon tetrachloride (CCl₄) are those that are non-polar: Br₂, C₆H₁₁OH, CS₂, and I₂, because CCl₄ is a non-polar solvent and 'like dissolves like'.

Explanation:

The question asks which compound in each pair is likely to be more soluble in carbon tetrachloride (CCl₄). Solubility often depends on the similarity principle 'like dissolves like', meaning that polar solvents dissolve polar substances, and non-polar solvents dissolve non-polar substances.

a) Br₂ or NaBr: Br₂ (bromine) is a non-polar molecule, while NaBr (sodium bromide) is an ionic compound. Br₂ will be more soluble in CCl₄ since both are non-polar.

b) CH₃OH or C₆H₁₁OH: C₆H₁₁OH (cyclohexanol) is less polar and has a longer non-polar hydrocarbon chain compared to CH₃OH (methanol). Thus, C₆H₁₁OH will be more soluble in CCl₄.

c) CS₂ or KOH: CS₂ (carbon disulfide) is a non-polar molecule, while KOH (potassium hydroxide) is an ionic and polar compound. CS₂ will be more soluble in CCl4.

d) I2 or CaF₂: I₂ (iodine) is a non-polar molecule, while CaF₂ (calcium fluoride) is an ionic compound. I2 will be more soluble in CCl₄.

Final answer:

To find equilibrium concentrations for the given chemical reaction with Kc=4.0, we use an ICE table to set up the initial concentrations, calculate the change, and determine the equilibrium concentrations for each species. We solve for 'x' the amount of reactants that change to form the products, and then back-calculate the concentrations of A, B, and C at equilibrium.

Explanation:

The student's question requires understanding how to calculate equilibrium concentrations for a chemical reaction with a given equilibrium constant (Kc). The reaction given is aA(g) + bB(g) ⇌ cC(g), with Kc = 4.0. To find the equilibrium concentrations of A, B, and C, we can set up an ICE (Initial, Change, Equilibrium) table, with initial concentrations of A and B at 1.0 M and C at 0 M. If x is the amount of A and B that react to reach equilibrium, then the equilibrium concentrations would be [A] = 1 - ax, [B] = 1 - bx, and [C] = cx. We then plug these into the equilibrium expression Kc = [C]c / ([A]a[B]b).

For the given reaction where a = 1, b = 1, and c = 2, and given Kc, we substitute 1 - x for [A] and [B], and 2x for [C], since no C is initially present. We would then solve for x and back-calculate [A], [B], and [C]. However, to give a definitive answer, we would need the actual values for a, b, and c applied to this specific reaction, not the placeholders.

Answer:

a

Explanation: