A student is participating in the school science fair. She wants to investigate household cleaners.

Which question can she best answer through scientific investigation?

A. Which household cleaner is most effective at removing stains?
B. Which household cleaner smells the best?
C. How often should a person use household cleaners?
D. Where should a person buy household cleaners?

Answer:

49.35  mL

Explanation:

Given: 56.2 mL of gas

To find: volume that 56.2 mL of gas at 820 mm of Hg would occupy at 720 mm of Hg

Solution:

At 820 mm of Hg, volume of gas is 56.2 mL

At 1 mm of Hg, volume of gas is \(\frac{56.2}{820}\)

At 720 mm of Hg, volume of gas is \(\frac{56.2}{820}(720)=49.35\,\,mL\)

If you add 5 ml of 0.5 M NaOH solution to 20 ml each of buffer B (with a pH of 4.03) and buffer C, the buffer whose pH will change the least is buffer B.

What is a buffer?

A buffer is a solution that resists changes in pH when acid or alkali is added. A buffer solution is a solution that contains a weak acid and its corresponding weak base or a weak base and its corresponding weak acid.

The Henderson-Hasselbalch equation can be used to calculate the pH of a buffer solution before and after adding a strong base or acid.

The equation is pH = pKa + log ([A-]/[HA])

where:pKa is the dissociation constant for the acid[A-] is the conjugate base of the acid when a command (such as NaOH) is added to a buffer solution, the base reacts with the weak acid to form the conjugate base of the acid and water. The addition of the conjugate base of the acid causes the pH of the solution to rising.

When an acid (such as HCl) is added to a buffer solution, the acid reacts with the weak base to form the conjugate acid of the base and water. The addition of the conjugate acid of the base causes the pH of the solution to decrease. Based on the above equation, pH change will be minimum in Buffer B. Therefore, the buffer whose pH will change the least is buffer B.

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The chemical is least soluble in water at 50 degrees celsius is not enough information give. option D is correct.

The solubility of a chemical in water depends on various factors, including temperature. At 50 degrees Celsius, the chemical that is least soluble in water is (c) KNO3, also known as potassium nitrate. Potassium chloride (KCl) and sodium chloride (NaCl) are more soluble in water at this temperature. As for option (d), "not enough information," it does not apply in this case since we have the necessary information to determine the solubility.

solubility is the extent to which a substance dissolves in a solvent to form a solution (usually measured in grams of solute per liter of solvent). Solvency of one liquid (fluid or gas) in another might be finished (absolutely miscible; e.g., methanol and water) or fractional (oil and water break up just somewhat)

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The chlorophyll processes the ingredients to make

(plant food) and

Answer:

oxygen

Explanation:

Answer:

Explanation:

The density of a substance can be found by using the formula

\(density = \frac{mass}{volume}\\\)

From the question we have

mass = 418.23 g

volume = 436.2 ml

\(density = \frac{418.23}{436 .2} \\ = 0.958803\)

We have the final answer as

Hope this helps you

The aqueous solution that has the lower freezing point is 0.60 m glucose.

Freezing point depression is the reduction in the temperature at which a liquid freezes caused by dissolved particles. The freezing point depression (ΔTf) of a solution is proportional to the molality (m) of the solute, which is the number of moles of solute per kilogram of solvent.

Freezing point depression is a colligative property, which means it depends only on the number of solute particles in the solution, not on their nature. The van't Hoff factor (i) is used to account for the dissociation of solutes in the solution. The van't Hoff factor of glucose is 1, whereas the van't Hoff factor of CaCl2 is 3.

To calculate the freezing point depression, we use the formula:

ΔTf = i * Kf * m

To calculate the freezing point depression, we use the formula:

ΔTf = i * Kf * m

The freezing point depression constant of water is 1.86 °C/m.

Thus, for the given molality of the solutions, the freezing point depression is

:ΔTfcacl2 = 3 * 1.86 °C/m * 0.60 m = 3.348 °CΔTfglucose = 1 * 1.86 °C/m * 0.60 m = 1.116 °C

Therefore, 0.60 m glucose has a lower freezing point depression than 0.60 m CaCl2.

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a) The pH of a 0.20 M solution of methanoic acid is 2.10.and b) The pH of a solution of 6.8 g of solid methanoic acid dissolved in 2.0 L of distilled water is 2.99.

a) For a 0.20 M solution of methanoic acid:

The balanced equation for the ionization of methanoic acid is:

HCOOH + H₂O ⇌ H₃O⁺ + HCOO⁻

The equilibrium constant expression for this reaction is:

Kₐ = [H₃O⁺][HCOO⁻]/[HCOOH]

Since methanoic acid is a weak acid, we can assume that the concentration of H₃O⁺ and HCOO⁻ ions produced is much smaller than the initial concentration of methanoic acid. Therefore, we can use the approximation that [HCOOH] ≈ [HCOOH]₀, where [HCOOH]₀ is the initial concentration of methanoic acid.

Let x be the concentration of H₃O⁺ and HCOO⁻ ions produced. Then:

Kₐ = x²/[HCOOH]₀

Rearranging and solving for x, we get:

x = √(Kₐ[HCOOH]₀) = sqrt(1.6x10⁻⁴ x 0.20) = 0.008

Therefore, [H₃O⁺] = [HCOO⁻] = 0.008 M

The pH of the solution can be calculated using the definition of pH:

pH = -log[H₃O⁺] = -log(0.008) = 2.10

Therefore, the pH of a 0.20 M solution of methanoic acid is 2.10.

b) For a solution of 6.8 g of solid methanoic acid dissolved in 2.0 L of distilled water:

First, we need to calculate the number of moles of methanoic acid in the solution:

molar mass of HCOOH = 46.03 g/mol

moles of HCOOH = mass / molar mass = 6.8 g / 46.03 g/mol = 0.148 mol

The concentration of the methanoic acid solution is:

concentration = moles / volume = 0.148 mol / 2.0 L = 0.074 M

Since the concentration of the solution is less than the concentration used in part (a), we can assume that the ionization of methanoic acid is negligible. Therefore, the pH of the solution will be determined by the concentration of HCOOH.

Using the definition of pH, we get:

pH = -log[H₃O⁺] = -log(Kₐ × [HCOOH]0) / 2 = -log(1.6x10⁻⁴ x 0.074) / 2 = 2.99

Therefore, the pH of the solution of 6.8 g of solid methanoic acid dissolved in 2.0 L of distilled water is 2.99.

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Answer: Elements in the same family generally have similar properties because they contain the same number of the electrons, for instance.

Hope this helped!

Answer:

Explanation:

The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere. Carbon is released back into the atmosphere when organisms die, volcanoes erupt, fires blaze, fossil fuels are burned, and through a variety of other mechanisms.

A system of linear equations to balance the following chemical reaction:

Limestone, CaCO₃, neutralizes the acid, H₃ O, in acid rain is:

2H₃O + CaCO₃ → 3H₂O + Ca + CO₂

To balance the chemical equation:

H₃O + CaCO₃ → H₂O + Ca + CO₂

We need to ensure that the number of atoms of each element is the same on both sides of the equation.

Let's assign variables to the coefficients of each compound:

H₃O: x

CaCO₃: y

H₂O: z

Ca: a

CO₂: b

Now, we can set up the system of equations based on the number of atoms for each element:

For hydrogen (H):

3x = 2z

For oxygen (O):

3x + 3y = 2z

For calcium (Ca):

y = a

For carbon (C):

y = b

For calcium (Ca):

a = 1

Solving this system of equations will give us the balanced coefficients. Let's solve it:

From the equation y = a, we have y = 1.

From the equation y = b, we have b = 1.

Substituting b = 1 into the equation 3x + 3y = 2z, we have:

3x + 3 = 2z

From the equation 3x = 2z, we have x = (2/3)z.

Substituting x = (2/3)z into the equation 3x = 2z, we have:

3(2/3)z = 2z

2z = 2z

This equation is true for any value of z, indicating that z can take any value.

Therefore, we can choose z = 3 to simplify the coefficients:

x = (2/3)z = (2/3)(3) = 2

y = 1

z = 3

a = 1

b = 1

Thus, the balanced equation is:

2H₃O + CaCO₃ → 3H₂O + Ca + CO₂

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Answer:

second (S) is the SI unit of time.

Answer:

second

Explanation:

the gap between any two intervals is called time

time can be measured in hour,minute,second

but second is the SI unit of time

Each ion has a single charge, one positive and one negative, so we need only one ion of each to balance the overall charge. When writing the ionic formula, we follow two additional conventions: (1) write the formula for the cation first and the formula for the anion next, but (2) do not write the charges on the ions.

Answer:

The final volume of gas is 9.19 L.

Explanation:

Given that,

Volume = 10.0 L

Initial pressure = 1.50 atm

Final pressure = 1240 mmHg

We need to calculate the final volume of gas

Using formula of ideal gas

\(P_{1}V_{1}=P_{2}V_{2}\)

\(V_{2}=\dfrac{P_{1}V_{1}}{P_{2}}\)

Where, P₁ = initial pressure

P₂ = final pressure

V₁ = initial volume

Put the value into the formula

\(V_{2}=\dfrac{1.50\times10\times760}{1240}\)

\(V_{2}=9.19\ L\)

Hence, The final volume of gas is 9.19 L.

The activation energy for a reaction is changed from 237 kj/mol to 57.9 Kj/mol at 653 k by the introduction of a catalyst. of the uncatalyzed reaction takes about 2290 years to occur then about 1.64 * 10³yr⁻¹ will be consumed by uncatalyzed reaction if we assume the frequency factor a is constant and assume the initial concentrations are the same.

Activation energy for uncatalyzed energy,

Eₐ(1) = 237kJ/mol

Activation energy for catalyzed reaction,

57.9 kJ/mol

Time taken by uncatalyzed reaction,

t₁=2290 years

Temperature, T=653 K

First, we will find the rate constant for the uncatalyzed reaction:

k ∝ 1/t

k₁ = 1/2290yr=0.00040 yr⁻¹

The rate constant the catalyzed reaction (k2) is calculated as follows:

\(ln\frac{K_{2} }{K_{1} }\) = \(\frac{E_{a(1) -E_{a(2)} } }{RT_{} }\)

R=8.314 J/K⋅mol

K₂ = -6.08 * 10⁻⁴ yr⁻¹

Now, we will find time taken by catalyzed reaction:

t₂ = 1/k₂

t₂ = 1.64 * 10³yr⁻¹

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The required quantum numbers are;

The term quantum number is used to describe the position of an electron in an atom. Now we know that each electron in atom is defined by four sets of quantum numbers.

Now;

For the circled electron in the arsenic atom, the four quantum numbers are;

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Answer:  d) -705.55 kJ

Explanation:

Heat of reaction is the change of enthalpy during a chemical reaction with all substances in their standard states.

\(2CO_2(g)+2H_2O(l)\rightarrow C_2H_4(g)+3O_2(g)\) \(\Delta H=+1411.1kJ\)

Reversing the reaction, changes the sign of \(\Delta H\)

\(C_2H_4(g)+3O_2(g)\rightarrow 2CO_2(g)+2H_2O(l)\)

\(\Delta H=-1411.1kJ\)

On multiplying the reaction by \(\frac{1}{2}\) , enthalpy gets half:

\(0.5C_2H_4(g)+1.5O_2(g)\rightarrow CO_2(g)+H_2O(l)\)\(\Delta H=\frac{1}{2}\times -1411.1kJ=-705.55kJ/mol\)

Thus the enthalpy change for the given reaction is -705.55kJ

Explanation:

The group number gives you the number of electrons the elements will have on its outer shell and the period number tells you the number of shells the elements will have. I hope that was helpful!

Periodic table helps us in knowing the electronic configuration of any element.  If we know the location of element in the periodic table then we can determine the arrangements of electrons in the periodic table easily.

Periodic table is a table in which we find elements with properties like metals, non metals, metalloids and radioactive element arranges in increasing atomic number.

Periodic table help a scientist to know what are the different types of elements are present in periodic table so that they can discover the new elements that are not being discovered yet.

The group number gives you the number of electrons the elements will have in its outermost shell and the period number tells you the number of shells the elements will have.

Therefore if we know the location of element in the periodic table then we can determine the arrangements of electrons in the periodic table easily.

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Answer:

the Sun, planets, satellites, comets, asteroids and meteoroids.

Explanation:

hope it helps :)

Answer:

e.g converting 6.55×10^24 molecules of Sodium to moles.

We use Avogadro's number NA= 6.02×10^23 molecules.

Explanation:

\(6.02 \times {10 }^{23} molecules \: are \: in \: 1 \: mole \: of \: sodium \\ 6.55 \times {10}^{24} molecules \: will \: be \: in \: ( \frac{6.55 \times {10}^{24} \times 1}{6.02 \times {10}^{23} } ) \\ = 10.88 \: moles \: of \: sodium\)

Answer:

Applied research

Explanation:

The process of developing a new vaccine involves the use of known scientific theories to address specific problems. Here, the outcome of several basic research are put into use to arrive at a targeted outcome. This outcome/product can be continuously modified (if it shows early promise) until the desired effect is achieved and if no "promise" is discovered at critical points of this research, work on this theory (for this research) is suspended another theory is pursued.

This process (described above) in which scientists continuously develop new treatments and/or vaccines and continuously subject it to testing until the desired effect is achieved can be referred to as Applied research.

Answer:

Matter is any substance, if it is made up of only one kind of atom, then it is an element. Elements consists of atoms with the same weight and same number of protons in the nuclei.

Answer:

2:true

3: true

4:false

5: true

Explanation:

The main reservoirs of the carbon cycle are the atmosphere, oceans, land (including vegetation and soils), and fossil fuels. In these reservoirs, carbon exists in both inorganic and organic forms.

The inorganic carbon cycle involves the exchange of carbon dioxide (CO2) between the atmosphere and oceans through processes like photosynthesis and respiration.

Organic carbon, on the other hand, is found in living organisms, dead organic matter, and soil organic matter. It is cycled through processes such as decomposition and consumption by organisms. The interactions between the inorganic and organic carbon cycles occur primarily in the biosphere, where photosynthesis converts inorganic carbon into organic carbon compounds. While inorganic carbon is primarily in the form of CO2, organic carbon is present in complex organic molecules. Both forms of carbon play crucial roles in energy transfer, nutrient cycling, and climate regulation.

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Backbone of DNA is made of phosphate and sugar residues

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Answer:

The answer is B. The number of atoms on each side of the reaction arrow must be the same.

Explanation:

Check your work to make certain you have the same number and type of atoms on the reactants side as on the products side

Answer:

A mole ratio is the ratio between the amounts in moles of any two compounds involved in a chemical reaction. ... The mole ratio may be determined by examining the coefficients in front of formulas in a balanced chemical equation. Also known as: The mole ratio is also called the mole-to-mole ratio.