Select the correct answer.
In which research method does a researcher change the value of one variable to determine how the change affects another variable?
O A experiment
OB. observational research
Oc.
survey
OD
case study

The groups of the periodic table from left to right are alkali metals, alkaline earth metals,transition metals,halogens and noble gases.

Periodic table is a tabular arrangement of elements in the form of a table. In the periodic table, elements are arranged according to the modern periodic law which states that the properties of elements are a periodic function of their atomic numbers.

It is called as periodic because properties repeat after regular intervals of atomic numbers . It is a tabular arrangement consisting of seven horizontal rows called periods and eighteen vertical columns called groups.

Elements present in the same group have same number of valence electrons and hence have similar properties while elements present in the same period show gradual variation in properties due to addition of one electron for each successive element in a period.

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7.11 × 10⁻⁴ is the solubility (in M) of PbCl\(_2\) in a 0.15 M solution of HCl. The Ksp of PbCl\(_2\) is 1.6 x 10⁻⁵.

The capability of a material, the solute, to combine with another material, the solvent, is known as solubility in chemistry. Insolubility, or the solute's inability to create such a solution, is the opposite attribute.

The amount of each of the solute within a saturated solution—a solution whereby no more solute is able to be dissolved—is typically used to gauge the degree of a substance's solubility in a particular solvent.

PbCl\(_2\) ⇌ Pb\(_2\)⁺(x) + 2Cl⁻ (2x)

HCl ⇌H⁺ (0.15M) + Cl⁻ (0.15M)

Ksp = {Pb\(_2\)⁺} {Cl⁻}²

Ksp = {x} {2x+ 0.15}²

2x<0.15

Ksp = {x} {0.15}²

x = 7.11 × 10⁻⁴

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The general gas equation, commonly referred to as the ideal gas law, represents the state of a fictitious ideal gas through an equation. Here the mass of helium gas required to pressurize 86 L tank to 201 atm is 2561.8 g.

According to the ideal gas law, the sum of the absolute temperature of the gas and the universal gas constant is equal to the product of the pressure and volume of one gram of an ideal gas.

The ideal gas equation is given as:

PV = nRT

n = PV / RT

56°C = 329 K

n = 201 × 86 / 0.08206 × 329 = 640.45 mol

Molar mass of 'He' = 4.00 g / mol

Mass =  640.45 × 4.00 = 2561.8 g

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Answer:

the temperature increased

Answer:

PbS shows a very low solubility in water, and it is insoluble in organic solvents. Any "dissolution" process in acids (hydrochloric acid, nitric acid, aqua regia) is accompanied with a chemical reaction whereby H2S is liberated and the corresponding soluble Pb2+ salts are formed. hope that helps

Draw a structural formula for the major product of the reaction shown:

The structural formula for the major product (2-butene) of the given reaction is as follows:$$\ce{CH3CH2CH=CH2}$$

The given reaction is an acid-catalyzed dehydration reaction.

During the reaction, the hydroxyl group (OH) and the adjacent hydrogen atoms (H) on the reactant alcohol (2-butanol) undergo dehydration (loss of water) to form an alkene (2-butene) as the major product.

The reaction is shown below:$$\ce{CH3CH2CH2CH2OH + H2SO4 ->[\Delta] CH3CH2CH=CH2 + H2O}$$To draw the structural formula for the major product of the given reaction, we need to consider the following points:

1. The reactant alcohol (2-butanol) is a four-carbon alcohol with the hydroxyl group (OH) attached to the second carbon atom (C2) of the chain.

2. The product alkene (2-butene) will be a four-carbon alkene with a double bond between the second and third carbon atoms (C2 and C3) of the chain.

The other two carbon atoms will have a single bond with the adjacent carbon atoms and a hydrogen atom each attached to them.

3. The major product will be formed via the elimination of water (dehydration) between the hydroxyl group (OH) and the adjacent hydrogen atoms (H) on the second carbon atom (C2) of the reactant alcohol (2-butanol).

4. The acid catalyst (H2SO4) does not participate in the reaction and remains unchanged. It only facilitates the formation of the alkene by providing a proton (H+) to the hydroxyl group (OH) and a medium for the elimination of water.

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The balanced chemical equation in acidic solution is as follows: Cr₂O₇²−(aq) +  3 HNO₂(aq) ⎯→2  Cr₃+(aq) + 3 NO₃−(aq) + 4 H₂O(l).

Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.

The first chemical equation was put forth by Jean Beguin in 1615.By making use of chemical equations the direction of reaction ,state of reactants and products can be stated. In the chemical equations even the temperature to be maintained and catalyst can be mentioned.

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Answer:

Nucleons

Explanation:

Isobar elements has same number of nucleons (sum of protons and neutrons).

a) The saturated solubility level of KCl (aq) at 40°C is 35.7 g/100 mL of water.

b) No, the solution would not be saturated at 90°C. At this temperature, the solubility of KCl in water is higher than at 40°C. Therefore, more KCl can dissolve in 100 g of water at 90°C than at 40°C. To determine if the solution is saturated, we need to compare the amount of KCl that actually dissolved in the water to the maximum amount of KCl that can dissolve in the water at that temperature. If the amount of KCl that dissolved is less than the maximum amount, then the solution is unsaturated. If the amount of KCl that dissolved is equal to the maximum amount, then the solution is saturated. If the amount of KCl that dissolved is greater than the maximum amount, then the solution is supersaturated.

c) Two ways in which saturation can be achieved if only 40 g of KCl is added to 100 g of water at 90°C are:

i) Heating the solution to a higher temperature: As the temperature of the solution is increased, the solubility of KCl in water also increases. Therefore, by heating the solution to a higher temperature than 90°C, more KCl can be dissolved in the water until the solution becomes saturated.

ii) Allowing the solution to cool slowly: If the solutionis heated to a temperature higher than 90°C and then allowed to cool slowly, the solubility of KCl in water decreases as the temperature decreases. This means that as the solution cools, KCl will begin to precipitate out of the solution until the solution becomes saturated. Alternatively, if the solution is left undisturbed at 90°C and allowed to cool slowly, KCl will begin to precipitate out of the solution as it reaches its saturation point.

The structure of the branched ether of chemical formula c4h10o, is \(CH_3 - CH_2 - CH_2 - O - CH_2 - CH_2 - CH_3.\)

\(C_4H_{10} O\) is a branched ether, also known as an alkoxyalkane or a glycol ether. It is an organic compound composed of four carbon atoms, ten hydrogen atoms, and one oxygen atom. Its molecular formula is \(C_4H_{10} O\)and its molecular weight is 86.13 g/mol.

Its structure is linear, with a carbon backbone and an oxygen atom attached to two of the carbons in the chain. The oxygen atom is then connected to two methyl (\(CH_3\)) groups, one on each side of the central carbon atom.

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Answer:  343 Celsius

Explanation:

Gay lussac law

T2=T1V2/V1  Temp must be in Kelvin

T2= 308.15 X 9.00 / 4.50 =616.30 K - 273.15 to get back in celsius

=343.15 C

Answer:

hola comoe stas

Explanation:

gracias x los puntos

Answer:

Number of protons in Carbon - 14 atom \(6\)

Explanation:

The atomic number of carbon 14 atom is \(14\)

Number of neutrons in the nucleus of Carbon-14 atom \(= 8\)

Atomic number is equal to the sum of neutrons and protons

Number of protons in Carbon - 14 atom \(= 14 -8 = 6\)

Answer:

Carbon dioxide is made up of one carbon atom, two oxygen atoms. There are four covalent bonds in one molecule of carbon dioxide. Carbon and oxygen are non-metals, thus we know carbon dioxide is a covalent compound.

Answer:

It is no. D

Explanation:

Many meteoroids are formed from the collision of asteroids, which orbit the sun between the paths of Mars and Jupiter in a region called the asteroid belt.

Answer:

i think paint

Explanation:

The balanced equation is:

4 NO(g) + O₂(g) ⇒ 2 N₂O₃(g)

The expression of the rate in terms of change in concentrations are:

\(v = \frac{-\Delta [NO]}{4\Delta t } = \frac{-\Delta [O_2]}{1\Delta t } = \frac{\Delta [N_2O_3]}{2\Delta t }\)

When N₂O₃ is forming at 0.221 M/s, NO is disappearing at 0.442 M/s.

The reaction rate is the speed at which a chemical reaction takes place, defined as proportional to the increase in the concentration of a product per unit time and to the decrease in the concentration of a reactant per unit time.

4 NO(g) + O₂(g) ⇒ 2 N₂O₃(g)

We will need to consider the stoichiometric coefficient of each species.

\(v = \frac{-\Delta [NO]}{4\Delta t } = \frac{-\Delta [O_2]}{1\Delta t } = \frac{\Delta [N_2O_3]}{2\Delta t }\)

The molar ratio of NO to N₂O₃ is 4:2.

\(\frac{0.221molN_2O3}{L.s} \times \frac{4molNO}{2molN_2O_3} = \frac{0.442 molNO}{L.s}\)

The balanced equation is:

4 NO(g) + O₂(g) ⇒ 2 N₂O₃(g)

The expression of the rate in terms of change in concentrations are:

\(v = \frac{-\Delta [NO]}{4\Delta t } = \frac{-\Delta [O_2]}{1\Delta t } = \frac{\Delta [N_2O_3]}{2\Delta t }\)

When N₂O₃ is forming at 0.221 M/s, NO is disappearing at 0.442 M/s.

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Answer:

We need more? What else is in the question? This is unanswerable.

Explanation:

Answer: pH ≈ 3.186

Explanation:

\(p^{H} &=p^{k a}+\left[\frac{A^{-}}{H A}\right] \\3.26 &=p^{k a}+ \log \frac{0.37}{0.34} \\3.26 &=p^{k a}+\log\ 1.089 \\3.26 &=p^{k e}+0.037 \\p^{k a} &=3.26-0.1105 \\p^{k a} &=3.1495\)

\($0.34 \frac{\mathrm{mol}}{2} \times 0.71 \mathrm{~L}=0.2414 \ {\mathrm{mol} \rightarrow HA \\\\\)

\($0.37 \frac{\mathrm{mol}}{2} \times 0.71 \mathrm{~L}=0.2627 \ {\mathrm{mol} \rightarrow A^{-} \\\\\)

\($0.2414-0.032 \mathrm{mol}=0.2094 \mathrm{\ mol} \ HA\)

\($0.2627+0.032 \mathrm{mol}=0.2947 \mathrm{\ mol} \ A^{-}\)

\(\begin{aligned}&p H=3.1495+\log\frac{0.2627}{0.2414} \\&p H=3.1495+0.0367 \\&p H=3.186\end{aligned}\)

Therefore, the pH after 0.032 mol of HCl are added to 0.71 L of the solution is approximately 3.186

Answer:

(A) 1.962x10^-10 M solubility in pure water

(B) 4.0 x 10^-33 M solubility

(C) 4.0 x 10^-27 M solubility

Explanation:

(A) Fe(OH)3 would give (Fe3+) and (3OH-)

Ksp = [Fe^3+][OH-]^3 = 4.0 x 10^-38

Let y = [Fe^3+]

Let 3y = [OH-]

4x10^-38 = (y)(3y)^3

4x10^-38 = 27y^4

y^4 = 4x10^-38 ÷ 27

y^4 = 1.481 x 10^-39

y = 1.962x10^-10 M solubility in pure water

(B) pH = 5.0

5.0 = - log [OH-]

-5.0 = log [OH-]

[OH-] = 10^-5.0 =  1.0 x 10^-5 M

So, Ksp = [Fe^3+][OH-]^3 = 4.0 x 10^-38

[Fe^3+][1.0 x 10^-5] = 4.0 x 10^-38

[Fe^3+] = 4.0 x 10^-38 ÷ 1.0 x 10^-5

= 4.0 x 10^-33 M solubility

(C) pH = 11.0

11.0 = - log [OH-]

-11.0 = log [OH-]

[OH-] = 10^-11.0 =  1.0 x 10^-11 M

So, Ksp = [Fe^3+][OH-]^3 = 4.0 x 10^-38

[Fe^3+][1.0 x 10^-11] = 4.0 x 10^-38

[Fe^3+] = 4.0 x 10^-38 ÷ 1.0 x 10^-11

= 4.0 x 10^-27 M solubility

The catalyst for the reaction is I2 and the step which is slower is second step

The rate law expression shows that the rate of the reaction is directly proportional to the concentration of I2. This indicates that I2 is involved in the rate-determining step of the reaction, which is likely the slowest step in the overall reaction.

From the mechanism given, we can see that the first step involves the reaction between CH3CHO and I2 to form CH3I, HI, and CO. The second step involves the reaction between CH3I and HI to form CH4 and I2. The rate of the overall reaction will be limited by the slower of these two steps.

To determine the slower step, we need to look at the reaction intermediates in each step. In the first step, the intermediate HI is a radical, which is highly reactive and likely to react quickly with other species present in the reaction mixture. In contrast, in the second step, the intermediate CH3I is relatively stable and less likely to react quickly with other species.

Therefore, the slower step is likely the second step, which involves the reaction between CH3I and HI to form CH4 and I2. This step is likely rate-determining and determines the overall rate of the reaction.

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the complete question is :

At 800 K, the rate of decomposition of aldehyde (CH3CHO) into CCH and CO follows the rate law: r=K[CCH3CHO][I2]. The decomposition is thought to follow a two-step mechanism:

CH3CHO+I2→CH3I+HI+CHOCH3I+HI→CH4+I2

What is the reaction's catalyst? Which of the two steps is the more difficult?

Answer:

See explanation

Explanation:

We know that

%ic of the interatomic bond = [1 - e^-(XA - XB)^2/4] * 100%

Now;

XA = electronegativity of Ti = 1.61

XB = electronegativity of Al = 1.54

Substituting values;

%ic of the interatomic bond = [1 - e^-(1.61 - 1.54)^2/4] * 100%

%ic of the interatomic bond = 0.12%

Given the low %ic of the interatomic bond, the bond is metallic.

The percent ionic character is 0% and the type of interatomic bonding would be metallic.

The percent ionic character can be determined by using the formula,

\(1-exp{-0.25(Xa-Xb)^{2} ]\)

• In the given equation, Xa and Xb refers to the electronegativities of the elements.  

• The intermetallic compound given is TiAl₃.  

• Based on the electronegativity table, the electronegativity of Al or Xa is 1.5 and the electronegativity of Ti or Xb is 1.5.  

Now putting the values in the above formula we get the % ionic character,

\(= 1-exp [-0.25 (Xa -Xb)^{2}]*100%\\\\\\=1-exp [-0.25 (1.5 -1.5)^{2}]*100%\\\)

\(= 0 percent\)

Thus, the ionic bond character is 0% and the compound TiAl₃ comprises two metals, it exhibits metallic bonding.

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Answer:

About 7.0 × 10³ J or 7.0 kJ

Explanation:

We want to determine the amount of energy needed to raise the temperature of 67 grams of water from 20°C to 45°C.

We can use the heat equation:

\(\displaystyle q = mC\Delta T\)

Where C is the specific heat of water.

Substitute and evaluate:

\(\displaystyle \begin{aligned} q & = (67\text{ g})\left(\frac{4.2\text{ J}}{\text{g-$^\circ$C}}\right)\left(45^\circ \text{ C}- 20.^\circ\text{ C}\right) \\ \\ & = (67\text{ g})\left(\frac{4.2\text{ J}}{\text{g-$^\circ$C}}\right)(25^\circ \text{ C}) \\ \\ & = 7.0\times 10^3 \text{ J}\end{aligned}\)

Recall that there are 1000 J in a kJ. Hence:

\(\displaystyle \begin{aligned} q & = 7.0\times 10^3 \text{ J} \cdot \frac{1\text{ kJ}}{1000\text{ J}} \\ \\ & = 7.0 \text{ kJ}\end{aligned}\)

In conclusion, it will take about 7.0 × 10³ J or 7.0 kJ of energy to raise the temperature of 67 grams of water from 20 °C to 45 °C.

The discovery that water vapor will stick to smoke particles is relevant to cloud seeding, which is the process of introducing substances into clouds to promote the formation of rain or other forms of precipitation.

By dispersing smoke particles or other suitable substances into clouds, water vapor can condense around these particles and form water droplets, eventually leading to the development of rain. This technology is used in situations where there is a need for additional rainfall, such as in areas experiencing drought or in agricultural settings where water is needed for crop growth. Cloud seeding can help enhance precipitation and increase water resources, contributing to water supply management and agricultural practices.

Hence, the correct statement is option d seed clouds to produce rain.

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Answer:primary consumer

Explanation:

i got it right

Answer:

okay I will help you just message me johnpatrick on messenger

Answer:

m

Explanation: