Why are valence electrons important?

A compound is a substance composed of two or more different atoms chemically bonded to one another, for example, water (H₂O) consists of 2 atoms of hydrogen (H) and 1 atom of oxygen (O), so it is the compound. Water is created by chemical reaction:

2H₂ + O₂ → 2H₂O

Answer: C. 118

Explanation:

Depending on what version you are using, most periodic tables have more than 92 elements on a periodic table.

Answer: Option (a) is the correct answer.

Explanation:

Ionic compounds have atoms bonded through ionic bonds.

An ionic bond is formed when there is transfer of electrons from one atom to another. Also, ionic compounds have opposite charge on their atoms hence, they are attracted by strong intermolecular forces.

Thus, compound whose atoms are holded by strong intermolecular forces of attraction are solid.

Therefore, we can conclude that ionic compounds are normally in solid physical state at room temperature.

The percent composition of each element in vinegar, also known as acetic acid, is as follows: Carbon - 39.9%, Hydrogen - 6.7%, and Oxygen - 53.4%, calculated using their respective atomic masses and the molar mass of acetic acid.

The chemical formula for vinegar, which is also known as acetic acid, is C2H4O2. Each molecule of vinegar contains two atoms of Carbon (C), four atoms of Hydrogen (H), and two atoms of Oxygen (O). The percent composition of each element in vinegar can be calculated using their atomic masses and the overall molar mass of vinegar.

The molar mass of acetic acid is 60.06 g/mol. Using this information and the atomic masses of carbon (12.01 g/mol), hydrogen (1.01 g/mol), and oxygen (16.00 g/mol), we can calculate the percent composition by volume of each element in vinegar as follows: Carbon constitutes 39.9%, Hydrogen constitutes 6.7%, and Oxygen constitutes 53.4% of the total composition.

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Answer:

B. O₃ + O → CS + 2O₂

Explanation:

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The answer is: B. metal.

Metals conduct an electric current in liquid and solid state, because they have mobile electrons.

Metallic bond is formed between electrons and positively charged metal ions.

Metallic bond increace electrical and thermal conductivity.

For example, thermal conductivity of sodium is 140 W/(m·K).

Nonmetals have low electrical and thermal conductivity.

By balancing the equation, we ensure that the number of atoms of each element is the same on both sides of the equation. The balanced equation is:

C₂H₄ + 3O₂ → 2CO₂ + 2H₂O

Let's break down the equation and explain how it is balanced step by step:

C₂H₄ + O₂ → CO₂ + H₂O

To balance the equation, we need to ensure that the number of atoms of each element is the same on both sides.

Starting with carbon (C), we have 2 carbon atoms on the left side (in C₂H₄) and 1 carbon atom on the right side (in CO₂). To balance the carbon, we place a coefficient of 2 in front of CO₂:

C₂H₄ + O₂ → 2 CO₂ + H₂O

Next, let's move on to hydrogen (H). We have 4 hydrogen atoms on the left side (in C₂H₄) and 2 hydrogen atoms on the right side (in  H₂O). To balance the hydrogen, we place a coefficient of 2 in front of  H₂O:

C₂H₄ + O₂ → 2 CO₂ + 2 H₂O

Finally, we'll look at oxygen (O). On the left side, we have 2 oxygen atoms from O2, and on the right side, we have 4 oxygen atoms from 2CO₂ and 2H₂O. To balance the oxygen, we need to have the same number of oxygen atoms on both sides. Since we have 2 oxygen atoms in O₂, we need to multiply it by 2 to get 4 oxygen atoms:

C₂H₄ + 2 O₂ → 2 CO₂ + 2 H₂O

Now the equation is balanced, with an equal number of atoms of each element on both sides.

Hence, the balanced equation is C₂H₄ + 2 O₂ → 2 CO₂ + 2 H₂O

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Answer:

[tex]V_{m} = \frac{V}{n}[/tex]

Explanation:

Molar volume is the volume occupied by 1 mole of a substance.

For gases, based on the ideal gas law we have:

[tex]PV = nRT[/tex]

where, P = pressure, V= volume, n = moles, R = gas constant, T = temperature

[tex]\frac{V}{n} = \frac{RT}{P}[/tex]

Here, the molar volume is given as:

[tex]V_{m} = \frac{V}{n}[/tex]

Under standard temperature and pressure conditions, the molar volume of an ideal gas is 22.4 L/mol

Answer: Conditions it was formed under, where it was formed, and what it is composed of.

Explanation:

Answer:

The relationship between where elements is located in a block and super scripted value appearing at the end of the electronic configuration is that it gives information on the group the element exist in each block.

Explanation:

Blocks in the periodic table are divided as S, P, D AND F blocks.  Representing elements with a electronic configuration gives information on the block that the elements falls on . For example Sodium and fluorine configurations are as follows ;

Sodium → 1s²2s²2p∧6 3s∧1

flourine → 1s²2s²2p∧5

The outer shell that ends the configuration determines the block it belongs. In this case sodium belongs to the s block while fluorine belongs to the p blocks. Then the super scripted value which is 1 for sodium depict it belong to group 1 of the s blocks. The super scripted  value for fluorine which is 5 shows the element belongs to group 5 in the p blocks.

The block in which an element is located in the Periodic Table determines the type of subshell the last electron occupies. The superscript at the end of the electron configuration indicates the number of electrons in the corresponding subshell.

The location of an element within a block in the Periodic Table determines the type of subshell that the last electron occupies. The electron configuration details in what order the electrons fill up in different orbitals in an atom. In an electron configuration, the superscripted value - often referred to as the exponent - indicates the number of electrons in a particular subshell.

For instance, if an element is located in the 's block', the superscript value will represent the number of electrons in an 's' orbital. Similarly, if an element is located in the 'p block', the superscript value at the end of the electron configuration will denote the number of electrons in a 'p' orbital. In a d block, the d orbital's electron count is represented, and for the f block, the f orbital's.

This connection between electron configuration, blocks in the Periodic Table, and location of an element is a fundamental concept in the study of atomic structure and chemistry.

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As

Answer: The volume of solvent evaporated is 173.57 mL

Explanation:

[tex]\text{Molarity of the solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (in mL)}}[/tex]    .....(1)

Molarity of solution = 0.275 M

Volume of solution = 230.0 mL

Putting values in equation 1, we get:

[tex]0.275M=\frac{\text{Moles of solution}\times 1000}{230.0}\\\\\text{Moles of solution}=\frac{0.275\times 230}{1000}=0.0632mol[/tex]

As, the moles of solution remains the same.

When solvent gets evaporated, the volume of the solution is calculated by using equation 1:

Moles of solution = 0.0632 moles

Molarity of the solution = 1.15 M

Putting values in equation 1, we get:

[tex]1.15=\frac{0.0632\times 1000}{\text{Volume of solution}}\\\\\text{Volume of solution}=\frac{0.0632\times 1000}{1.15}=56.43mL[/tex]

Volume of solution evaporated = (230.0 - 56.43) mL = 173.57 mL

Hence, the volume of solvent evaporated is 173.57 mL

Answer: It does not change.

Explanation:

[tex]H_2CO_3(aq) +H_2O\rightarrow H_3O^+(aq)+HCO_3^-(aq)[/tex]

According to Le Chatelier's principle, if an equilibrium reaction is subjected to a change, the reaction adjusts itself in a way to undo the change imposed.

The effect of pressure affects the equilibrium only when the reactants or products are in gaseous phase.

As none of the reactants or products is in gaseous state, there is no effect of pressure on equilibrium.

The equilibrium of the reaction H₂CO₃ + H₂O <-> H₃O⁺ + HCO₃⁻ is not affected by changes in pressure because it does not involve gases. This is in contrast to reactions involving gases, where increasing pressure favors the side with fewer moles of gas.

The reaction H₂CO₃ + H₂O <-> H₃O⁺ + HCO₃⁻ takes place in water and has reached equilibrium. When the pressure is increased, the equilibrium will shift according to Le Chatelier's principle. Since there are no gases on either side of the equilibrium, pressure changes will not affect the position of the equilibrium. However, this differs from the equilibrium of a reaction involving gases, such as C(s) + H₂O(g) = CO(g) + H₂(g), where increasing pressure would favor the side with fewer moles of gas, shifting the equilibrium to the left.

Letter A. do not react with other or chemically.

B. The ignition point for a given fuel is met.

Combustion is a process in which there is reaction between a substance and oxygen which gives off heat. Thus, the source of oxygen is called the oxidizer while the substance is called the fuel. However, the fuel can be inform of liquid, solid or gas and the process of combustion releases heat.

Answer: The order with respect to B is

Explanation: Rate law says that rate of a reaction is directly proportional to the concentration of the reactants each raised to a stoichiometric coefficient determined experimentally called as order.

[tex]Rate=k[A]^x[B]^y[/tex]

k= rate constant

x = order with respect to A

y = order with respect to B

n = x+y = Total order

a) From trial 1: [tex]20=k[0.20]^x[0.10]^y[/tex]    (1)

From trial 2: [tex]40=k[0.20]^x[0.20]^y[/tex]    (2)

Dividing 2 by 1 :[tex]\frac{40}{20}=\frac{k[0.20]^x[0.20]^y}{k[0.20]^x[0.10]^y}[/tex]

[tex]2=2^y,2^1=2^y[/tex] therefore y=1.

Thus order with respect to B is 1.

Given the data in the accompanying table, the reaction order for B is 1st order. The correct option is B.

We may study how the initial rate of the reaction varies when the initial concentration of B is changed to establish the reaction order for B.

We can detect the link between the rate and the concentration of B by comparing the start rate of the reaction at different initial concentrations of B.

Based on the information provided:

Initial concentration of B: [B] (mol/L)

Initial rate: mol/Ls

When [B] is 0.20 mol/L, the initial rate is 20 mol/Ls.

When [B] is 0.40 mol/L, the initial rate is 160 mol/Ls.

As we can see, increasing the initial concentration of B (from 0.20 mol/L to 0.40 mol/L) doubles the initial rate (from 20 mol/Ls to 160 mol/Ls). This suggests that the starting rate and the concentration of B have a direct proportional connection.

Here, one can conclude that the reaction order for B is 1st order. Therefore, the correct answer is B) first.

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The molarity of the solutions are found by dividing the number of moles of solute by the volume of solution in liters. For glucose, the molarity is 0.5 M; for KOH, it is approximately 0.03565 M; and for NaCl, it is approximately 0.25025 M.

The question asks for the calculation of the molarity of different solutions. Molarity is defined as the number of moles of solute divided by the volume of solution in liters.

Calculations:

a. For 2.0 moles of glucose in 4.0L of solution, the molarity (M) is calculated as follows:
M \\= moles of solute / volume of solution in liters
M \\= 2.0 moles / 4.0 L
M \\= 0.5 M

b. For 4.0 g of KOH in 2.0 L of solution, we first need to calculate the number of moles of KOH, which involves finding the molar mass (KOH has a molar mass of approximately 56.11 g/mol):
Moles of KOH \\= mass (g) / molar mass (g/mol)
Moles of KOH \\= 4.0 g / 56.11 g/mol
Moles of KOH \\= ~0.0713 moles
Thus, the molarity of KOH is:
M \\= 0.0713 moles / 2.0 L
M \\= 0.03565 M

c. For 5.85 g of NaCl in 400 mL (or 0.400 L) of solution, firstly convert the mass of NaCl into moles (NaCl has a molar mass of approximately 58.44 g/mol):
Moles of NaCl \\= mass (g) / molar mass (g/mol)
Moles of NaCl \\= 5.85 g / 58.44 g/mol
Moles of NaCl \\= ~0.1001 moles
The molarity of NaCl is:
M \\= 0.1001 moles / 0.400 L
M \\= 0.25025 M

In summary, the molarity of the given solutions are:

0.5 M of glucose

0.03565 M of KOH

0.25025 M of NaCl

Answer:

highest velocity

Explanation:

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Answer: The correct answer is Option A.

Explanation:

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as [tex]\Delta H^o[/tex]

The equation used to calculate enthalpy change is of a reaction is:  

[tex]\Delta H^o_{rxn}=\sum [n\times \Delta H^o_f(product)]-\sum [n\times \Delta H^o_f(reactant)][/tex]

For the given chemical reaction:

[tex]PbO(s)+CO(g)\rightarrow Pb(s)+CO_2(g);\Delta H^o=-131.4kJ[/tex]

The equation for the enthalpy change of the above reaction is:

[tex]\Delta H^o_{rxn}=[(1\times \Delta H^o_f_{(Pb(s))})+(1\times \Delta H^o_f_{(CO_2(g))})]-[(1\times \Delta H^o_f_{(PbO(s))})+(1\times \Delta H^o_f_{(CO(g))})][/tex]

We are given:

[tex]\Delta H^o_f_{(CO_2(g))}=-393.5kJ/mol\\\Delta H^o_f_{(CO(g))}=-110.5kJ/mol\\\Delta H^o_f_{(Pb(s))}=0kJ/mol\\\Delta H^o_{rxn}=-131.4kJ[/tex]

Putting values in above equation, we get:

[tex]-131.4=[(1\times \Delta H^o_f_{(0)})+(1\times (-393.5))]-[(1\times \Delta H^o_f_{(PbO(s))})+(1\times (-110.5))]\\\\\Delta H^o_f_{(PbO(s))}=-151.6kJ/mol[/tex]

Hence, the correct answer is Option A.

Answer: Option (A) is the correct answer.

Explanation:

When a solute is dissolved in a solvent then in order to dissolve the solute it is necessary that attractive forces between the solute must be broken such that solute molecules can combine with solvent molecules.

By increasing temperature, pressure, surface area etc of a solution we can break the attractive forces between the solute.

Thus, we can conclude that in order for a solute to dissolve in a solvent it is true that the attractive forces in a solute need to be broken.

When 2.0 moles of NH₃ are completely reacted according to the balanced chemical equation 4NH₃ + 5O₂ -> 4NO + 6H₂O, 3 moles of H₂O are produced using the mole ratio from the equation.

The question asks about a chemical reaction between ammonia (NH₃) and oxygen (O₂) to produce nitrogen oxide (NO) and water (H₂O). The balanced chemical equation for this reaction is 4NH₃(g) + 5O₂(g)
ightarrow 4NO(g) + 6H₂O(l). To find the maximum number of moles of H₂O produced when 2.0 moles of NH₃ are completely reacted, we use the mole ratio from the balanced equation.

According to the balanced equation, 4 moles of NH₃ produce 6 moles of H₂O. Therefore, we set up the following proportion: (6 moles H₂O) / (4 moles NH₃) = x moles H₂O / (2 moles NH₃). By cross-multiplying and solving for x, we find that 3 moles of H₂O will be produced.

Maximum 3 moles of H₂O can be produced from 2.0 moles of NH₃.

To determine the maximum number of moles of H₂O that can be produced when 2.0 moles of NH₃ are completely reacted, we can use the balanced chemical equation provided:

From the balanced equation, we can see that for every 4 moles of NH₃ that react, 6 moles of H₂O are produced.

Therefore, the maximum number of moles of H₂O that can be produced when 2.0 moles of NH₃ are completely reacted is 3 moles.

The correct answer is H20.

In a chemical reaction, there are always two sides, the reactant side and the product side. The reactants are the elements that are reacting together. They are always written at the left side of a chemical equation, with a plus sign written in between two elements. The products are the new compounds that are formed from the reaction of reactants. They are always written at the right side of a chemical equation and a plus sign is used to join them if they are more than one. An arrow pointing to the products usually connect the two side of the equation. For the question give above, the reactant are CH4 and O2 and the products are CO2 and H2O.

The four groups attached to the central carbon of an amino acid are an amino group ([tex]\rm -NH_2[/tex]), a carboxyl group ([tex]\rm -COOH[/tex]), a hydrogen atom ([tex]\rm -H[/tex]), and a side chain group (also called an R group).

Amino acid is an organic compound which is defined as the amine substituted carboxylic acid.

-The amino group (-NH2) and carboxyl group (-COOH) are both functional groups that are involved in the formation of peptide bonds between amino acids during protein synthesis.

-The hydrogen atom (-H) is simply a single proton that is attached to the central carbon atom of the amino acid.

-The side chain group (R group) is a variable group that differs between different amino acids. The R group can be a simple alkyl group, a complex aromatic group, or a charged group, among others.

Therefore, an amino group ([tex]\rm -NH_2[/tex]), a carboxyl group ([tex]\rm -COOH[/tex]), a hydrogen atom ([tex]\rm -H[/tex]), and a side chain group (also called an R group) are the four groups attached to the central carbon of an amino acid.

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Final answer:

Amino acids have four distinct groups attached to a central alpha carbon: an alpha-amine group, an alpha-carboxyl group, a hydrogen atom, and a variable R-group unique to each amino acid.

Explanation:

Every amino acid consists of four groups covalently attached to a central alpha carbon, also known as the α-carbon. These include:

This structure is essential in biology for protein synthesis, as amino acids are the building blocks of proteins. Each amino acid's specific R-group influences the protein's structure and function.