When collecting gases over water, it is important that:

A. the reaction flask be sealed from the atmosphere

B. the gases do not react with water molecules

C. the collection flask is only partially filled with water

D. all of the above

To measure out 75 ml of the 5 M stock solution to make a 250 ml solution with a concentration of 1.50 M.

To find the volume of the 5 Molar (M) stock solution needed to make a 250 ml solution with a concentration of 1.50 M, you can use the dilution formula:

C1V1 = C2V2

Where:
C1 = concentration of the stock solution
V1 = volume of the stock solution
C2 = desired concentration of the final solution
V2 = desired volume of the final solution

In this case, the concentration of the stock solution (C1) is 5 M, the desired concentration of the final solution (C2) is 1.50 M, and the desired volume of the final solution (V2) is 250 ml.

Plugging in the values into the formula:

(5 M)(V1) = (1.50 M)(250 ml)

Now, solve for V1:

V1 = (1.50 M)(250 ml) / (5 M)
V1 = 75 ml

Therefore, you would need to measure out 75 ml of the 5 M stock solution to make a 250 ml solution with a concentration of 1.50 M.

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Formula

\(\ell=\frac{n h}{2 \pi}\)

\(\ell = angular \: momentum\)

\(n = principal quantum number \\ h = Planck's constant \\ \pi = pi\)

b) It provides information concerning the number of rings plus the number of pi bonds in a molecule of a given compound.

The "index of hydrogen deficiency" is a term used in organic chemistry to describe the degree of unsaturation (i.e. the number of double bonds, triple bonds, and rings) in a compound. This information can be obtained from a mass spectrum by analyzing the peaks corresponding to the molecular ions and using the formula for calculating the index of hydrogen deficiency. The number of molecules of H2 that must be supplied to a structure in order to produce the equivalent saturated, acyclic species is measured by the Index of Hydrogen Deficiency (IHD). As a result, the IHD counts the number of numerous bonds and rings in the structure.

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If more air molecules will be introduced into the bag and the pressure of the air molecules will decrease inside the bag according to Boyle's law.

Boyle's law states that the volume of a given mass of gas is inversely proportional to its pressure at constant temperature.

If we continue to inflate the airbag, more air molecules will be introduced into the bag and the pressure of the air molecules will decrease inside the bag according to Boyle's law.

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Answer:

Dark matter was first suspected in clusters of galaxies when the galaxies were found to move with too high a speed to be retained in the cluster by their gravitational influence on each other

Answer:

Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect, or emit electromagnetic radiation and is, therefore, difficult to detect.

1. Lithium 2. Fluorine 3. Aluminum

Bohr's atomic model came into existence with the modification of Rutherford's model of an atom. Bohr explained that the electrons move in fixed orbitals and also explained that each orbit has a fixed energy.

Postulates are given by Bohr:

Based on these postulates the names of atoms shown in the figure are:

1. Lithium: Atomic number is 3 therefore, it has three protons in the nucleus.

2. Fluorine: Atomic number is 9 and it has 9 protons in the nucleus.

3. Aluminum: Atomic number is 13 and it has 13 protons in the nucleus.

Differences of Bohr's atomic model and Rutherford's atomic model:

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Answer: Use Hot Water.

Explanation:

To unclog a toilet without a plunger all u need to do is boil some water and carefully pour that into the toilet. Wait for some time and then pour some more hot water. Keep repeating this process till the water level starts going down.

Answer: The solution with pH of 14 will be a strong base.

Explanation:

pH or pOH is the measure of acidity or alkalinity of a solution.

pH is calculated by taking negative logarithm of hydrogen ion concentration.

\(pH=-log[H^+]\)

Acids have pH ranging from 1 to 6.9, bases have pH ranging from 7.1 to 14 and neutral solutions have pH equal to 7. Thus pH scale range from 1 to 14.

Strong acids have low pH ( around 1 ) values where as strong bases have high pH ( around 14) values.

Answer:

on my test the answer was a strong acid

Explanation:

Answer:

it's harmful

Explanation:

it's harmful to our environment it can endanger our planet and endangered animal species it can also kill lots of plants and we have a hard time burning fossil fuels with limited factories which costs a lot of money.

The number of grams of water that would be required to make a mixture that contained 60 grams of salt is 16 g.

The ratio shows the comparison of one thing to another. The ratio sign is ':' IT is used between two variables.

It is given that salt, baking soda, and water in a 20:15:10 ratio by mass are mixed

The mixture contains 24 grams of baking soda

Mass of Water = ?

Baking Soda: Water = 15:10

Let the mass of water is x

then the ratio is 24 : x

As both these ratios are equal

15 : 10 = 24 : x

15 / 10 = 24 / x

x = 24 x 10 / 15

x = 16 gm

Thus, the number of grams of water is 16 gm.

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Answer:

151.87dm³

Explanation:

Given parameters:

Volume of hydrogen gas  = 6.78mole

Unknown:

Volume of hydrogen gas formed at STP  = ?

Solution:

To solve this problem;

   1 mole of a gas at STP  = 22.4dm³ So;

   6.78 mole of gas  = 6.78 x 22.4  = 151.87dm³

Answer:

70°C,130.9 ................,...

Answer:

m= 85.7g

V= 32.4mL

d= m/V

d= 2.65g/mL

The answer to the problem 3.96 * 0.1159 is : 0.459 (3 significant figures)

Significant figures can be defined as numbers in a group of numbers that place number in the right value or worth.

Significant figures defined the value of measurement of  a particular number.

The rules of engagement in this case is the set of rules or laid down principles that direct how we interact with this significant figures and how they are used.

For this case the significant figures of the product will be the same as the figure with the least significant figure in the multiplication.

In conclusion, The answer to the problem 3.96 * 0.1159 is : 0.459 (3 significant figures)

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The number of atoms in 0.0082g of gold is 2.50 x 10^19 atoms.

What is a molar mass in chemistry?

Molar mass is the mass of one mole of a substance, usually expressed in grams per mole (g/mol). It is a fundamental concept in chemistry that allows us to relate the mass of a substance to the number of atoms or molecules present.

The molar mass of gold (Au) is approximately 197 g/mol. To find the number of atoms in 0.0082 g of gold, we first need to calculate the number of moles of gold present:

moles of gold = mass of gold / molar mass of gold moles of gold = 0.0082 g / 197 g/mol moles of gold = 4.16 x 10^-5 mol

Next, we can use Avogadro's number (6.022 x 10^23 atoms/mol) to convert the number of moles to the number of atoms:

number of atoms = moles of gold x Avogadro's number number of atoms = 4.16 x 10^-5 mol x 6.022 x 10^23 atoms/mol number of atoms = 2.50 x 10^19 atoms

Therefore, there are approximately 2.50 x 10^19 atoms in 0.0082 g of gold.

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Answer:

S

Explanation:

The symbol for entropy is S, and a change in entropy is shown as “delta” S or ΔS. If the entropy of a system increases, ΔS is positive. If the entropy of a system decreases, ΔS is negative.

The time (in years) taken for only 10 mg to remain is 14.84 billion years

N × 2ⁿ = N₀

10 × 2ⁿ = 100

Divide both side by 10

2ⁿ = 100 / 10

2ⁿ = 10

Take the log of both side

Log 2ⁿ = Log 10

nLog 2 = Log 10

Divide both side by Log 2

n = Log 10 / Log 2

n = 3.32

How to determine the time (in years)

t = n × t½

t = 3.32 × 4.47

t = 14.84 billion years

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The number of molecules in 10.0 gram of NaOH is 15 * 10²².

To solve this question, we need to understand some terms of mole concept,

Mole - It is the amount of substance containing same number of molecules or atoms as there are atoms in 12 gram of carbon-12 isotope.

Molecules - It is group of atoms bonded together, representing the smallest fundamental unit of a chemical compound taking part in chemical reaction.

Molecular weight - The sum of atomic masses of all atoms in molecules.

Avogadro number - It is the number of atoms, ions, electrons, molecules in one mole of substance. It is represented as NA.

NA = 6.0 * 10²³ (approx)

To calculate the number of molecules, we apply the formulae,

no. of molecules = moles * NA

moles = weight / molecular weight

moles = 10.0 / 40

          = 0.25

Substituting this value to calculate number of molecules,

no. of molecules = 0.25 * 6.0 * 10²³

                            = 15 * 10²²

Therefore the number of molecules of in 10.0 g of NaOH is 15 * 10²².

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Answer:

...................

.

Si el polímero tiene un grupo amida, entonces se considera poliamida, mientras que si el polímero tiene un grupo éster, entonces es una poliamida.

La poliamida es un tipo de polímero en el que una sustancia compuesta de moléculas largas de unidades múltiples. En este tipo de polímero, las unidades repetitivas de la cadena molecular están unidas entre sí por grupos amida.

El poliéster es una categoría de polímeros que contienen el grupo funcional éster en cada unidad repetida de su cadena principal. Como material específico, también se le llama tereftalato de polietileno (PET).

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The AGº for the phosphorylation of ADP by phosphoenolpyruvate is equal to 32 kJ/mol.

The AGº for the phosphorylation of ADP by phosphoenolpyruvate can be calculated using the equation:

AGº = AGº (ATP hydrolysis) - AGº (phosphoenolpyruvate hydrolysis)

Given that AGº (ATP hydrolysis) = -30 kJ/mol and AGº (phosphoenolpyruvate hydrolysis) = -62 kJ/mol, then:

AGº = -30 kJ/mol - (-62 kJ/mol) = 32 kJ/mol

NADH: An increase in the concentration of NADH can inhibit PDH, as it competes with pyruvate for binding to the active site of the enzyme.

Acetyl-CoA: An increase in the concentration of acetyl-CoA can also inhibit PDH, as it acts as an allosteric inhibitor

Therefore, the AGº for the phosphorylation of ADP by phosphoenolpyruvate is equal to 32 kJ/mol.

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A research question or problem statement must be created before the scientific method can be used.

What is research?

This is the starting point of the scientific process, as it identifies the specific issue or phenomenon to be investigated. Once the research question or problem statement has been formulated, the researcher can develop a hypothesis and design an experiment or research study to test the hypothesis. The scientific method is a systematic approach to answering questions or solving problems through observation, experimentation, and analysis of data. It provides a framework for conducting scientific research in a structured and rigorous manner.

What is hypothesis ?

A hypothesis is a proposed explanation or prediction for a phenomenon or an observed relationship between variables that is based on limited evidence or prior knowledge. It is an educated and testable prediction or explanation about a particular phenomenon. A hypothesis is often used as a basis for designing experiments or conducting research studies to determine whether the predictions or explanations are supported or not. A hypothesis should be clear, specific, and testable to allow for scientific investigation and evaluation. In scientific research, a hypothesis is an essential element of the scientific method, providing a framework for formulating a research question, designing an experiment, and analyzing data.

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Answer:

Explanations:

Given the operation below:

Grouping the operation into standard and exponential values will give:

Simplify the result

Write the resulting product in standard form:

Hence the coefficient (green) is 4.3615 and the exponent (yellow) is -1.

When an aldehyde is treated with LiAlH4 followed by the addition of water, a primary alcohol results as a general class of product.

LiAlH4 is a strong reducing agent, which reduces carbonyl groups (such as aldehydes and ketones) to primary alcohols. The reaction between an aldehyde and LiAlH4 is an example of a nucleophilic addition reaction, in which the Lewis acidic LiAlH4 acts as a Lewis acid, accepting electrons from the nucleophile (the aldehyde), and forming a complex intermediate. The addition of water then hydrolyzes the intermediate to form a primary alcohol.

The reaction between the aldehyde and LiAlH4 is a two-step process:

Step 1: Formation of a complex intermediate

RCHO + LiAlH4 --> RCH(OH)2

Step 2: Hydrolysis of the intermediate

RCH(OH)2 + H2O --> RCH2OH + H3O+

The final product, RCH2OH, is a primary alcohol, which is a general class of product that results from the reaction of an aldehyde with LiAlH4 followed by the addition of water. The reaction mechanism can be more complex and may involve intermediate steps, but the overall reaction results in the reduction of the carbonyl group to a primary alcohol.

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Answer:

Give the test to a company that gives permission for the drug to given to the rest of the world.

Explanation:

The balanced equation for the dissociation of PO43- is given by;PO43-(aq)  H2O(l) ⇌ HPO42-(aq)  OH-(aq)The phosphate ion, PO43-, reacts with water to form HPO42- (monohydrogen phosphate) and OH- ions.

The chemical equilibrium between these species is represented by the equation above. In the dissociation reaction of PO43- the phosphate ion reacts with water (H2O) to form monohydrogen phosphate ion (HPO42-) and hydroxide ion (OH-). The reaction can be described as;PO43-(aq)  H2O(l) ⇌ HPO42-(aq)  OH-(aq)where the reactants are on the left and products on the right. In the equation, the state of matter of each reactant or product is written in parenthesis after its chemical formula. In this reaction, the reactant PO43- is an aqueous solution, while H2O is a liquid.

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Answer:

19

Explanation:

Answer:

19

Explanation:

This tells you that potassium has 19 protons and - since the number of protons is the same as the number of electrons- also 19 electrons. To find out the number of neutrons you have to look at the atomic mass or weight of the element.

Answer:Aluminum metal in silver nitrate ….

You might be expecting silver metal, Ag, and aluminum nitrate, Al(NO3)3, as products. But instead all you will end up with is wet aluminum. The passivating layer of Al2O3 will prevent aluminum from reducing silver ions.

Explanation: Al(s) + AgNO3(aq) → No reaction

The two things we might do to the mixture to disrupt the Al2O3 surface will cause the Ag+ ions to react. Often a source of chloride ion is used because AlCl4^- will form, exposing the aluminum surface. But that will cause AgCl(s) to precipitate. You can also make the solution basic with NaOH and form Al(OH)4^-, but that will cause Ag2O(s) to form. (You will get Ag2O instead of AgOH.)

Concentrated acids will oxidize any aluminum metal that might be exposed if you were to add concentrated HNO3. That would simply enhance the