help me please, i have 20 auestions

The periodic table is composed of metals and nonmetals arranged in groups and periods.

The periodic table is an arrangement of elements in groups and periods based on their properties. The properties of elements repeat at regular intervals hence the term, "periodic".

The answers to the questions are;

7)  Element Families on the Periodic Table have similar properties. There are 18 families.

8) Alkali Metals are good conductors of heat and electricity.

9) There are a total of 38 elements that are grouped as Transition Metals.

10)  As opposed to metals, non-metals can be very opaque. They have no metallic luster and do not reflect light.

11)  All Lanthanide Series elements occur naturally except for promethium.

12)  All Actinide Series elements are radioactive and most are synthetic.

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The value of the equilibrium constant for this reaction is 2*10^-3 when bromine and water react to form hydrogen bromide and oxygen.

The equilibrium constant for this reaction can be calculated using the following equation:\(2Br2(g) + 2H2O(g) -- > 4HBr(g) + O2(g)\)

K = (pressure of HBr)^4 * pressure of O2/(pressure of Br2)^2 x (pressure of H2O)^2

Given that the pressure of Br2 at equilibrium = 81.1atm

the pressure of H2O at equilibrium = 26.2atm

the pressure of HBr at equilibrium = 9.22atm

the pressure of O2 at equilibrium = 1.42atm

K = \((9.22)^4 * 1.42/(81.1)^2 * (26.2)^2\)

K = 0.0022

Therefore, the equilibrium constant for this reaction is 2*10^-3

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Answer:

other guy is correct. it is C Quebec.

Explanation:

got it right on the unit test review, edge 2021

The factor most sensitive to changes in temperature is the thermal expansion coefficient of a material.

In physics, the sensitivity of a factor to changes in temperature is determined by its thermal expansion coefficient. The thermal expansion coefficient measures how much a material expands or contracts when its temperature changes. Different materials have different thermal expansion coefficients, which determine their sensitivity to temperature changes.

For example, solids generally expand when heated and contract when cooled. This is because the atoms or molecules in a solid vibrate more vigorously as the temperature increases, causing them to move further apart and the material to expand. Conversely, when the temperature decreases, the atoms or molecules vibrate less, causing the material to contract.

Gases, on the other hand, are highly sensitive to changes in temperature. When a gas is heated, its molecules move faster and collide more frequently, leading to an increase in pressure and volume. As a result, gases expand significantly with temperature increases. Conversely, when a gas is cooled, its molecules move slower and collide less frequently, leading to a decrease in pressure and volume.

Liquids also expand with temperature, but to a lesser extent than gases. The expansion of liquids is due to the increased kinetic energy of their molecules, which causes them to move further apart. However, the intermolecular forces in liquids are stronger than in gases, limiting their expansion.

Understanding the thermal expansion properties of materials is important in various fields. For example, in engineering and construction, knowledge of thermal expansion helps prevent structural damage caused by temperature changes. In manufacturing, it is crucial for designing and producing components that can withstand temperature variations without failure.

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The factor that is most sensitive to changes in temperature is the enzyme activity or enzymatic reactions.

What is an enzyme?

An enzyme is a biomolecule that is a catalyzer in various biological and chemical processes, accelerating the rate of a chemical reaction without itself being affected.

What is the effect of temperature on enzymes?

Temperature affects enzyme activity by modifying the enzyme's three-dimensional shape, leading to a higher rate of reaction until a particular temperature is reached, after which the reaction rate begins to decrease, resulting in enzyme denaturation and a decrease in enzyme activity.

Factors that affect enzyme activity are:

Temperature: Enzyme activity is highly influenced by temperature, with the optimal temperature for enzyme activity generally ranging from 30°C to 40°C, depending on the enzyme's origin. When the temperature is lowered, the enzyme activity slows down until it ceases to function, resulting in a decrease in the rate of reaction. The rate of reaction increases with increasing temperature until it reaches the maximum point at which the enzyme becomes denatured and stops functioning. Therefore, enzymes are the most temperature-sensitive factor.

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The gas phase decomposition of ethyl chloroformate (ClCOOC2H5C2H5Cl) produces carbon dioxide (CO2). The given information states that the rate constant at k is /s and the rate constant at k is /s. Additionally, the activation energy for the gas phase decomposition of ethyl chloroformate is given as kj/mol.

To further explain, the rate constant (k) is a measure of how quickly a reaction occurs. It represents the proportionality constant between the concentration of the reactants and the rate of the reaction.

In this case, the decomposition of ethyl chloroformate is a chemical reaction in which it breaks down into carbon dioxide. The rate constant (k) provides information about the speed at which this decomposition occurs.

The rate constant at k is /s indicates the rate of the decomposition reaction when the reactants are at a certain temperature and pressure. Similarly, the rate constant at k is /s represents the rate of the reaction at a different temperature and pressure.

The activation energy (Ea) is the minimum energy required for a reaction to occur. In the given information, it is specified as kj/mol. This means that in order for the decomposition of ethyl chloroformate to take place, a minimum energy of kj/mol must be provided.

It is important to note that the activation energy affects the rate constant. As the activation energy increases, the rate constant decreases, resulting in a slower reaction. Conversely, when the activation energy decreases, the rate constant increases, leading to a faster reaction.

In summary, the given information provides the rate constants (k) for the decomposition of ethyl chloroformate at different conditions, as well as the activation energy (Ea) required for the reaction to occur. The rate constant reflects the speed of the reaction, while the activation energy represents the minimum energy needed for the reaction to take place.

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Answer:

135,400

Explanation:

135.4*1000= 135400

Answer:

Students will know that scientists find answers to questions about the natural world in different ways. ... Students will be able to explain that some science investigations are not experiments because they DON'T involve testing a hypothesis by changing one variable while keeping the other factors constant.

Explanation:

It  really all depends on the levels of suspicion.

The best practices while sharing a lab balance with other students  are cleaning if dirt is present it is needed to be cleaned as it will introduce errors in the measurements.

Errors in chemical analysis result when there is a difference between observed value and the true value.If the magnitude of errors is large , it results in decrease in accuracy, reproducibility, and precision.

There are three types of errors:1) random error 2) systematic error 3) human error.The cause of random errors are difficult to quantify while the human errors can be minimized by taking a range of readings to reduce the error.

Errors while measuring boiling point may be human errors while noting down the boiling temperature or instrumental or systematic error if there is a fault in the thermometer.

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We can use Graham's law of effusion to solve this problem. Graham's law states that the rate of effusion of a gas is inversely proportional to the square root of its molecular mass.

Mathematically, this can be expressed as:
\(Rate₁ / Rate₂ = \sqrt{(M_2 / M_1)}\)
Here, Rate₁ and Rate₂ represent the effusion rates of the unshaded and shaded spheres respectively, and M₁ and M₂ represent their molecular masses.
We're given that it takes twice the time for the shaded spheres to effuse compared to the unshaded spheres. Since rate and time are inversely proportional, this means:
Rate₁ = 2 * Rate₂
Now we can plug this into Graham's law:
\((2 * Rate_1) / Rate_2 = \sqrt{(M_2 / M_1)}\)
Canceling out Rate₂, we get:
\(2 = \sqrt{(M_2 / 16)}\)
Square both sides:
4 = M₂ / 16
Now, solve for M₂:
M₂ = 4 * 16 = 64 g/mol
The closest numerical value for the molecular mass of the gas represented by unshaded spheres is not listed among the options you provided. However, based on the calculations, the answer should be 64 g/mol.

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The reason for counting skeletal electron pairs (SEP) 1 to determine the shape of a cluster is that SEP 1 reflects the number of 2-center-2-electron bonds. Option D.

A skeletal electron pair is the electron pair shared between two atoms in a compound. In molecular geometry, it is used to define the electron pair geometry of a molecule. It is a fundamental concept used to predict the shape of molecules based on Lewis dot structures.

The number of skeletal electron pairs is equal to the number of atoms surrounding the central atom. Each bond and lone pair of electrons around the central atom is considered to be a separate electron pair. This is because these electrons will repel each other and adjust their positions accordingly. This will determine the shape of the molecule.

Hence, the correct answer is Option D. Sep 1 reflects the number of 2-center-2-electron bonds.

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Answer:

A

Explanation:

Answer:

Zn2 + SO4 = Zn2(SO4)2

Explanation:

Formation of ES from E+P is a step that was negligible by Michaelis and Menten in an enzyme-catalyzed reaction.

Enzyme-catalyzed reaction:

The enzyme-substrate complex formation is in equilibrium with the enzyme and substrate; the decomposition of the complex into the product is the rate-limiting step, so the rate is proportional to both substrate and enzyme as long as the equilibrium can be shifted by either species.

The step that was negligible by Michaelis and Menten is:

Formation of ES

E + S ---------> ES --------> E + P

E = enzyme concentration

S = substrate concentration

P = product concentration

Therefore the formation of ES from E + P is negligible by Michaelis and Menten.

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The volume of a gas remains constant. Using the ideal gas law, when the temperature changes from 44 K to 88 K, the final pressure is twice the initial pressure. Similarly, when the temperature changes from 26.4 °C to 59.5 °C, the final pressure is 1.17 times the initial pressure.

We can use the ideal gas law to solve this problem, assuming that the amount of gas and volume are constant:

PV = nRT

where P is pressure, V is volume, n is the number of moles of gas, R is the ideal gas constant, and T is temperature in kelvin.

Since the volume is constant, we can write:

P1/T1 = P2/T2

where P1 is the initial pressure, T1 is the initial temperature, P2 is the final pressure, and T2 is the final temperature.

(a) If the temperature changes from 44 K to 88 K, we can write:

P1/44 = P2/88

Simplifying and solving for P2/P1, we get:

P2/P1 = 2

So the final pressure is twice the initial pressure.

(b) If the temperature changes from 26.4 oC (299.55 K) to 59.5 oC (332.65 K), we can write:

P1/299.55 = P2/332.65

Simplifying and solving for P2/P1, we get:

P2/P1 = 1.17

So the final pressure is 1.17 times the initial pressure.

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To determine the pH of the solution, we need to first calculate the concentration of propionic acid and sodium propionate in the solution.

Propionic acid has a molar mass of 74.08 g/mol, so 1.00 g is equal to 0.0135 mol.

Sodium propionate has a molar mass of 96.06 g/mol, so 1.0 g is equal to 0.0104 mol.

We can assume that all of the propionic acid will dissociate in water to form propanoate ions and hydrogen ions, according to the following equation:

CH3CH2COOH + H2O ↔ CH3CH2COO- + H3O+

The equilibrium constant for this reaction is Ka = 1.3 x 10^-5.

We can set up an ICE table to determine the concentration of propanoate and hydrogen ions:

Initial:     0.0135 M            0                 0
Change:     -x                    +x               +x
Equilibrium: 0.0135 - x         x                 x

Using the Ka expression, we can write:

Ka = [CH3CH2COO-][H3O+] / [CH3CH2COOH]

1.3 x 10^-5 = x^2 / (0.0135 - x)

Since x is small compared to 0.0135, we can simplify this to:

1.3 x 10^-5 = x^2 / 0.0135

Solving for x, we get:

x = 2.07 x 10^-4 M

Therefore, [H3O+] = 2.07 x 10^-4 M and [CH3CH2COO-] = 2.07 x 10^-4 M.

Now, we can calculate the concentration of sodium propionate by dividing the moles by the volume of the solution:

0.0104 mol / 0.5 L = 0.0208 M

Since sodium propionate completely dissociates in water to form propanoate ions and sodium ions, the concentration of propanoate ions is equal to the concentration of sodium propionate:

[CH3CH2COO-] = 0.0208 M

To calculate the pH, we can use the equation:

pH = -log[H3O+]

pH = -log(2.07 x 10^-4) = 3.68

Therefore, the pH of the solution is approximately 3.68.

The closest answer choice is (A) 3.78, so that would be the best choice.

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Answer:

B

Explanation:

Just took the test

Answer:

b

Explanation:

edge 2021

Explanation:

Lithium is an electropositive element that readily loses electrons.

Oxygen is electronegative and it will readily accept electrons.

 Due to this significant electronegativity differences between the two species they form electrovalent or ionic bonds between them.

  2atoms of Li lose two electrons:

      Li  →  Li²⁺ + e⁻

             Lithium isoelectronic with helium

 For oxygen;

      O + 2e⁻   →  O²⁻

                          Oxygen is isoelectronic with Neon

Two ions of the lithium combines with the oxygen to form the bond;

                   4Li + O₂  →  2Li₂O

The electrostatic attraction between the two ions forms the ionic bond

Equilibrium is a state in a chemical reaction where the rate of the forward reaction is equal to the rate of the reverse reaction, resulting in no net change in the concentrations of reactants and products. It is represented by a double arrow (⇌) in chemical equations. In the given equation: H₂O (g) + CO (g) ⇌ H₂(g) + CO₂(g) + 42 KJ

To shift the equilibrium to the right, one or more of the following could occur:

Increasing the concentration of H₂ or CO₂

Decreasing the concentration of H₂O or CO

Increasing the pressure

Removing some of the products (H₂ and CO₂)

Decreasing the temperature

To shift the equilibrium to the left, one or more of the following could occur:

Decreasing the concentration of H₂ or CO₂

Decreasing the pressure

Increasing the temperature

If pressure is increased, the equilibrium will shift in the direction that produces fewer moles of gas. In this case, since there are fewer moles of gas on the right side of the equation (H₂ and CO₂), the equilibrium will shift to the right. If heat is added, the equilibrium will shift in the endothermic direction to absorb the additional heat. In this case, the forward reaction is endothermic (42 KJ on the right side), so the equilibrium will shift to the right to consume the added heat.

If CO is added, the equilibrium will shift to the right to consume the additional CO.The concentration of H₂O and CO₂ will increase, while the concentrations of H₂ and CO will decrease until a new equilibrium is reached.

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The Keq for the reaction N₂ + 3H2 = 2NH3 if the equilibrium concentrations are Keq = 1.5. The correct option is D.

Keq is the ratio of the concentration of reactant to the concentration of the product.

The balanced equation is

N₂ + 3H₂  = 2NH₃

The equilibrium constant is \(\rm \dfrac{[NH_3]^2}{[N_2]\; [H_2]^3}\)

The given concentrations of the compounds have been:

Ammonia = 3 M

Nitrogen = 1 M

Hydrogen = 2 M

\(\rm \dfrac{9}{1\times 8} = 1.5\)

Thus, the correct option is D. Keq = 1.5.

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Answer: Keq = 1.33

Explanation: :/

Yes, dilation is a Nonrigid transformation.

A dilation and curettage procedure, which is also called a D&C, is a surgical procedure in which the cervix or the lower, narrow part of the uterus is dilated or expanded so that the uterine lining (endometrium) can be scraped with a curette (spoon-shaped instrument) to remove abnormal tissues.

Non-Rigid Transformations are those transformations that are not rigid.  Non-Rigid Transformations actually change the structure of our original object. For example, it can make our object bigger or smaller using scaling. Or, it can be "pushed" up or to the side using shearing. Basically, non-rigid transformations allows the object to increase or decrease in size.

Hence Dilation is a example of Nonrigid transformation

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The number of moles of Nitrogen : == 7.975

Given

9.60x10²⁴ molecules  of nitrogen dioxide (NO2)

Required

The number of moles

Solution

Reaction

N2 + 2O2 → 2NO2

moles of NO2 :

= 9.6 x 10²⁴ : 6.02 x 10²³

= 15.95

From the equation, mol N2 :

= 1/2 x mol NO2

= 1/2 x 15.95

= 7.975

The number of molecules :

= 8 x 6.02 x 10²³

= 4.816 x 10²⁴

Answer:

Rubidium (Rb).

Explanation:

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

Electronic configuration => 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s¹

Name of element =?

To know the name of the element with the above electronic configuration, we shall determine the atomic number of the element. This can be obtained as follow:

Number of electrons = 2 + 2 + 6 + 2 + 6 + 2 + 10 + 6 + 1

Number of electrons = 37

Next, we shall determine the number of protons. This can be obtained as follow:

From the question given above, the element has no charge. Hence the element contains equal numbers of protons and electrons.

Number of electrons = 37

Number of protons = number of electrons = 37

Next, we shall determine the atomic number. This can be obtained as follow:

The atomic number of an element is simply defined as the number of protons present in the atom of the element. Thus,

Atomic number = proton number

Proton is = 37

Therefore,

Atomic number = 37

Finally, we shall determine the name of the element by comparing the atomic number of those in the periodic table.

Thus, the element with the above electronic configuration is Rubidium (Rb) since no two elements have the same atomic number

Answer:

half of the genetic makeup from the mother and half from the father

Explanation:

Their mother passes one copy on to them through the egg, while their father passes the other one along (via the sperm). Each egg and sperm have a single set of 23 chromosomes. Two copies of each chromosome and two copies of each gene are present when the sperm fertilizes the egg, resulting in the formation of an embryo.

Answer:

you stink at

Explanation:

In the Lewis dot structure of PCl3 (phosphorus trichloride), there is one single bond, zero double bonds, and three lone pairs on the central atom. The Lewis dot structure of PCl3 consists of a phosphorus atom (P) surrounded by three chlorine atoms (Cl).

Each chlorine atom forms a single bond with the phosphorus atom, resulting in three single bonds. The remaining valence electrons on the phosphorus atom are represented as lone pairs, with three lone pairs in total.

The central phosphorus atom has an electron configuration of 3s²3p³, with five valence electrons. It forms three single bonds with the chlorine atoms, each bond representing the sharing of one electron pair.

The remaining two valence electrons on phosphorus form two lone pairs. This arrangement allows the phosphorus atom to achieve an octet configuration, satisfying the octet rule.

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Answer:..A.) Each chlorine atom shares a pair of electrons with the sulfur atom

Answer:

C. pH > pOH; Kw = 1.0 * 10^-14

Explanation:

The ion product of water, Kw = [H+]*[OH-] = 1.0 * 10^-14. It is a constant.

When an acid or base is added to water, its ion product does not change as it a constant. However, the relative concentrations of H+ ions and OH- ions will change depending on whether an acid or base is added to water.

When an acid is added to water, the concentration of H+ ions increases while that of OH- ions decreases, and vice versa.

Therefore, in the above situation where an acid is added to water, pH > pOH; Kw = 1.0 * 10^-14

Answer:

carbon dioxide

Explanation:

the carbon dioxide is bad for animals and can even harm the nature around us. Carbon dioxide is overall a non-safe gas for some animals and is used everyday.

Answer:

SLS functions in cleaning product as a surfactant, wetting surfaces, emulsifying or solubilizing oils, and suspending soil so that they can be rinsed away. This ingredient contributes foaming properties to cleaning products. SLS is safe for use in cleaning products.

Sodium lauryl sulfate and ammonium lauryl sulfate are surfactants that help with the mixing of oil and water. As such, they can clean the skin and hair by helping water to mix with oil and dirt so that they can be rinsed away or suspend poorly soluble ingredients in water.

The U.S. Food and Drug Administration (FDA) includes sodium lauryl sulfate on its list of multipurpose additives allowed to be directly added to food. Sodium lauryl sulfate and ammonium lauryl sulfate are also approved indirect food additives. For example, both ingredients are permitted to be used as components of coatings.

The safety of sodium lauryl sulfate and ammonium lauryl sulfate has been assessed by the Cosmetic Ingredient Review  (CIR) Expert Panel on two separate occasions (1983 and 2002), concluding each time that the data showed these ingredients were safe in formulations designed for brief, discontinuous use, followed by thorough rinsing from the surface of the skin. In products intended for prolonged contact with skin, concentrations should not exceed 1%.  

Sodium lauryl sulfate and ammonium lauryl sulfate may be used in cosmetics and personal care products marketed in Europe according to the general provisions of the Cosmetics Regulation of the European Union.

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1.1 moles

Stoichiometry allows us to convert units such as grams to moles.

Molar Mass

Before we can convert grams to moles, we need to understand molar mass. Molar mass is the number of grams per mole. For example, the molar mass of oxygen is 16 g/mol. This means that there are 16 grams in one mole. Inversely, there is one mole in 16 grams of oxygen. Molar mass is a constant for each element that can be found on a periodic table.

Now, for this conversion, we need to find the molar mass of MgCO₃. To do this, we need to find the molar mass of each element within the compound.

Now, multiply each molar mass by its subscript; then add the molar masses together.

The molar mass of MgCO₃ is 84.3 grams.

Converting to Moles

Now we need to use stoichiometry to convert grams to moles. So, we are going to divide the grams by the molar mass.

So, there are approximately 1.127 moles in 95 grams. However, due to significant figures, we round this to 1.1 moles.