Scientists are trying to find out why bees are dying in large numbers. Which best describes how the scientists will try to solve the problem?
A. They will do the same experiments to obtain similar evidence.
B. They will only work with scientists who share the same opinions.
C.
They will observe the same patterns and draw the same conclusions
D.
They will approach the problem in different ways but share ideas. ​

Standard enthalpy change refers to a change in the amount of energy in a reaction that occurs under standard conditions.

It is a property that measures the change in the amount of energy in a reaction involving the formation of substances from pure elements.

Such a reaction must happen under standard conditions which include 1-atmosphere pressure and 298.15 K temperature.

It is designated by  ΔH°.

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Answer:

D

Explanation:

bc im smart

From the equation; there are three particles in solution.

The term freezing point is the temperature at which a liquid substance is converted to solid. We know that this is colligative property thus it depends on the number of particles in solution.

The dissolution of K₂S gives us;

K₂S(s) ----> 2K^+(aq)  + S^2-(aq)

This implies that there are three particles in solution.

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Answer:

electromagnetic waves and mechanical waves

Explanation:

I think these two kinds of waves can transmit energy through a vaccume.

Hope I helped!

Electromagnetic waves.

Gravity waves.

Answer:

C. It has the same types of atoms on both sides of the reaction arrow.

A chemical equation is a symbolic representation of a chemical reaction; Reactants are represented on the left and the products on the right.

The law of conservation of mass states that in a closed system, mass is neither created nor destroyed during a chemical or physical reaction. The law of conservation of mass is applied whenever you balance a chemical equation. It is also applicable to stoichiometry. A balanced equation demonstrates the conservation of mass by having the same number of each type of atom on both sides of the arrow.

Consider the balanced equation for the combustion of methane.

[tex]CH_4 + 20_2 \implies CO_2 + 2H_2O[/tex]

All balanced chemical equations must have the same number of each type of atom on both sides of the arrow.

In this equation, we have 1 C atom, 4 H atoms, and 4 O atoms on each side of the arrow.

The number of atoms does not change, so the total mass of all the atoms is the same before and after the reaction. Mass is conserved.

The same atoms of the same element that are present in the reactants are also present in the products, according to the rule of conservation of matter.

This leads us to believe that the response to the question is true because: It has the same atom kinds on both sides of the reaction arrow (Option C)

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You test your hypothesis by completing an experiment.

We test our hypothesis by performing experiment or research because in an experiment, we test our hypothesis and collect data in order to draw a conclusion from it.

So we can conclude that you test your hypothesis by completing an experiment.

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Taking into account definition of percent yield, the percent yield for the reaction is 100%.

In first place, the balanced reaction is:

2 FeBr₃ + 3 Na₂S → Fе₂S₃ + 6 NaBr

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

The following rule of three can be applied: if by reaction stoichiometry 2 moles of FeBr₃ form 6 moles of NaBr, 2.36 moles of FeBr₃ form how many moles of NaBr?

[tex]moles of NaBr=\frac{2.36 moles of FeBr_{3}x6 moles of NaBr }{2 moles of FeBr_{3}}[/tex]

moles of NaBr= 7.08 moles

Then, 7.08 moles of NaBr can be produced from 2.36 moles of FeBr₃.

The percent yield is the ratio of the actual return to the theoretical return expressed as a percentage.

The percent yield is calculated as the experimental yield divided by the theoretical yield multiplied by 100%:

[tex]percent yield=\frac{actual yield}{theorical yield}x100[/tex]

where the theoretical yield is the amount of product acquired through the complete conversion of all reagents in the final product, that is, it is the maximum amount of product that could be formed from the given amounts of reagents.

In this case, being the molar mass of NaBr 102.9 g/mole, you know:

Replacing in the definition of percent yields:

[tex]percent yield=\frac{728.532 grams}{728.532 grams}x100[/tex]

Solving:

percent yield= 100%

Finally, the percent yield for the reaction is 100%.

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Answer: 87%

Explanation:

The mass number and charge of this atom or ion is 24  and charge +2

The mass number is equals to the total number of protons and neutrons in a nucleus.

In the give question, The number of neutrons is a distractor.

Only the number of electrons versus the number of protons determines ionic charge. The charge of the ion is +2

Hence, The mass number and charge of this atom or ion is 24  and charge +2

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2.56 L is the volume of air in his tank at a depth of 100 ft (3 atm) and a temperature of 24°C.

The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).

Given data:

[tex]P_1=1 atm[/tex]

[tex]V_1=3.20 L[/tex]

[tex]T_1[/tex]=30°C

[tex]P_2=3 atm[/tex]

[tex]V_2=?[/tex]

[tex]T_2=24°C[/tex]

Using the equation:

[tex]\frac{P_1V_1}{T_1}[/tex] =[tex]\frac{P_2V_2}{T_2}[/tex]

[tex]V_2[/tex] =(1 atm x 3.20 L x 24°C) ÷ 30°C

[tex]V_2[/tex] = 2.56 L

Hence,  2.56 L is the volume of air in his tank at a depth of 100 ft (3 atm) and a temperature of 24°C.

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A redox reaction is one in which oxidation and reduction occurs.

A redox reaction is one in which oxidation and reduction occurs. Oxidation involves electron loss while reduction involves electron gain.

For the compound NaI;

The oxidation half equation is - 2Na(s)  --->2Na^+(aq) + 2e

The reduction half equation is - I2 + 2e ---->2 I^-(aq)

Missing parts:

Write the anode half-reaction and cathode half-reaction for NaI.

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Taking into account the change of units, the pressure of the gas sample is 87.19 kPa.

In first place, the rule of three is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them.

That is, what is intended with it is to find the fourth term of a proportion knowing the other three.  

If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other (or when one magnitude decreases, so does the other) , the direct rule of three must be applied.

To solve a direct rule of three, the following formula must be followed, being a, b and c known data and x the variable to be calculated:

a ⇒ b

c ⇒ x

So: [tex]c=\frac{cxb}{a}[/tex]

The direct rule of three is the rule applied in this case where there is a change of units.

To perform in this case the conversion of units, you must first know that:

So, if 1 atm is 760 mmHg, how many atm equals 654 mmHg?

760 mmHg ⇒ 1 atm

654 mmHg ⇒ x

So: [tex]x=\frac{654 mmHgx1 atm}{760 mmHg}[/tex]

Solving:

x=0.86 atm

Now, if 101325 Pa are 1 atm, how many Pa equals 0.86 atm?

1 atm ⇒ 101325 Pa

0.86 atm ⇒ x

So: [tex]x=\frac{0.86 atmx101325 Pa}{1 atm}[/tex]

Solving:

x= 87,192.83 Pa

Finally, if 1 kPa is 1000 Pa, how many kPa equals 87,192.83 Pa?

1000 Pa ⇒ 1 kPa

87,192.83 Pa ⇒ x

So: [tex]x=\frac{87,192.83 Pax1 kPa}{1000 Pa}[/tex]

Solving:

x=87.19283 kPa≅ 87.19 kPa

In summary, the pressure of the gas sample is 87.19 kPa.

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Answer:

Option D

Explanation:

sour taste refers to acid hence B is wrong

Bases have pH higher than 7 so D is the correct answer

Answer:

Slippery, high pH, and caustic

(last option listed)

Explanation:

sour taste - acid feature

pH < 7 - acid feature [low pH]

dissolves metal - strong acid feature

bitter taste - base feature

slippery feel - base feature

pH > 7 - base feature [high pH]

dissolves metal - strong base feature

[essentially, traits of base can be described as opposites of acid traits]

So, if you combine these traits, "Slippery, high pH, and caustic" best describes characteristics of a base

2Al + 3Cl₂ → 2AlCl₃

mol Al = 2/3 x 1.25 = 0.83

mass Al = 0.83 x 27 g/mol = 22.41 g

According to the stoichiometry 21.66 grams of aluminum will react fully with 1.25 moles Cl₂.

Stoichiometry is the determination of proportions of elements or compounds in a chemical reaction. The related relations are based on law of conservation of mass and law of combining weights and volumes.

Stoichiometry is used in quantitative analysis for measuring concentrations of substances present in the sample.It is useful in balancing chemical reactions.

According to the chemical reaction between aluminium and chlorine, 2 moles of aluminium reacts with 3 moles of chlorine , thus,1.25 moles of chlorine will react 1.25×2/3=0.83 moles which is mass of aluminium =0.83×26=21.66 g.

Thus, 21.66 grams of aluminum will react fully with 1.25 moles Cl₂.

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Nitrogen is important for all humans because it is a major part of amino acids, which are the building constituents of proteins and of nucleic acids such as deoxyribonucleic acid, which transfers genetic information to the next generation.

It is the biogeochemical circuit that supplies nitrogen to living things and keeps it circulating in the biosphere.

Importance of the nitrogen :

Therefore, we can conclude that the nitrogen is a vital circuit for the existence of Humans and all other living organism since we are unable to fix nitrogen from its gaseous form.

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Answer:

D.) 5.0 x 10⁻⁹ M

Explanation:

The formula displaying the relationship between pH and hydrogen ion concentration is:

pH = -log[H⁺]

In this formula "[H⁺]" represents the concentration of hydrogen ions (given in molarity (M)). Therefore, to find this value, you need to take the inverse of the log. The manipulation looks like this:

pH = -log[H⁺]  ------------>  [H⁺] = 10^-pH

Note that the carrot (^) represents an exponent. Now, you can plug your pH value into the equation to find the molarity.

[H⁺] = 10^-pH

[H⁺] = 10^-8.3

[H⁺] = 5.0 x 10⁻⁹ M

Answer: Specific heat capacity is measured in J/g℃.

Explanation:

The specific heat capacity is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius.

Another thing you should know about specific heat capacity is its formula. The formula of specific heat capacity is: C= [tex]\frac{q}{m}[/tex]×ΔT

In the formula, q is the heat gained or lost by the system (measured in joules), m is the mass of the sample in grams, and △T is the temperature's change in ℃.

I hope this helps! Pls mark brainliest!! :)

Answer:

a) Black

b) Non-magnetic

c) No reaction with carbon disulphide.

d) i don't know sry

But i had to go through my 6th grade notes for this .____.

[tex]KNO_3[/tex] at 70°C = 130 gram

NaCl at 100°C= 40 gram

NH₂Cl at 90°C= 70 gram

Solubility is defined as the maximum amount of a substance that will dissolve in a given amount of solvent at a specified temperature.

Amount of a substance (called the solute) that dissolves in a unit volume of a liquid substance (called the solvent) to form a saturated solution under specified conditions of temperature and pressure. Solubility is expressed usually as moles of solute per 100 grams of solvent.

Hence,

[tex]KNO_3[/tex] at 70°C = 130 gram

NaCl at 100°C= 40 gram

NH₂Cl at 90°C= 70 gram

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0.139 moles of plutonium are present in a sample containing 8.4 x 10²² atoms of Pt.

The number of moles of a substance can be calculated using the following expression:

no of moles = no of molecules ÷ 6.02 × 10²³

According to this question, 8.4 × 10²² atoms of plutonium are present in the molecule of plutonium.

no of moles = 8.4 × 10²² = 6.02 × 10²³

no of moles = 1.39 × 10-¹

no of moles = 0.139moles

Therefore, 0.139 moles of plutonium are present in a sample containing 8.4 x 10²² atoms of Pt.

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Answer:

1.72 moles of H₂

Explanation:

The balanced equation

2Na+ 2H₂O → 2NaOH + 1C

tells us we'll get 1 mole of H₂ for every 2 moles of NaOH.  We can express this as a molar ratio:  (1 mole H₂)/(2 moles NaOH).

The reaction produces 138 g of NaOH.  Divide this mass by the molar mass of NaOH (39.99 g/mole)to obtain moles NaOH:

138g NaOH/(40 g/mole) = 3.45 moles of NaOH.

To find the moles H₂ produced, we can multiply the moles NaOH by the molar ratio from above:

(3.45 moles NaOH)*((1 mole H₂)/(2 moles NaOH) = (3.45/2) moles H₂.  [Note how the "moles NaOH" unit cancels, leaving just "moles H₂"]

We should produce 1.72 moles of H₂.

Explanation:

Hi there!

Chloroethane requires atleast one chlorine in ethane. It's general formula is CnH2n+1Cl. It mean it must have 2 carbons, 5 hydrogens and atleast one chlorine.

In addition, carbon-carbon bond must be single and chlorine is attached to either carbons. The carbon of this compound is SP³ hybridized and has bond angle of 120°.

Hope it helps!

Answer:

a.  3.72 [atm]

Explanation:

For a gas at constant temperature, (with no change in number of molecules of the gas), we can apply Boyle's Law:  [tex]P_1V_1=P_2V_2[/tex]

[tex](1.556[atm])(268.5[mL])=P_2(112.4[mL])[/tex]

[tex]\dfrac{(1.556[atm])(268.5[mL\!\!\!\!\!\!\!\!{--}])}{112.4[mL \!\!\!\!\!\!\!\!{--}]}=\dfrac{P_2(112.4[mL]\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!{-----})}{112.4[mL]\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!{-----}}[/tex]

[tex]3.716957[atm]=P_2[/tex]

It seems like the answer should have 4 significant figures since all of the other quantities have 4 significant figures, but the closest answer choice of those provided is a.  3.72

Answer:

17.25g

Explanation:

From our question, we have been asked to find the mass of water present.

The formula for finding specific heat is given by;

Q = mCp∆T

We have, Q = 0.507 J, ∆T = 0.007° C and we know that Cp of water is 4.2 J/g°C

Rearrange the formula making m the subject.

Which is given by;

m = (Q)/(Cp∆T)

Substituting for the known values

[tex]m \: = \frac{0.507}{4.2 \times 0.007}[/tex]

= 17.24489 g

= 17.25g

Answer:

17.32 gm

Explanation:

Specific heat of water is 4.182 J / g- c

4.182  J /g-c   =  .507/ ( .007 * gm)

solve for gm = 17.32  gm

the quality of being periodic the tangency to record the intervals

the prediotic of the sun sports cycle

The cutoff frequency for a certain element is 1.22 x 1015 Hz this is its

work function in eV that is Work done = 5.05 eV.

Definition of labor function is the power this is wished for a particle to return back from the indoors of a medium and spoil via the surface —used particularly of the photoelectric and thermionic emission of electrons from metals paintings function.

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The answer is C since both charge and mass have to be balanced on both sides of the equation.

Answer:

[tex]4 \frac{mol}{l} [/tex]

Explanation:

From the question, we have been asked to find the molarity of FeCl2 having a volume of 450 mL,

We have been provided with 225 g which is proportional to 1.8 moles.

We know that molarity of any solution should be in mol/L.

1 mole contained in 1 L means it has a molarity of 1 mol/L

Let's convert 450 mL to Litres which is,

[tex] \frac{450}{1000} litres[/tex]

= 0.450 L

Thus,

1 mole is contained in 1L

x moles are contained in 0.450 L

Hence,

x mole/molarity = {1 mole x 1 L}/{0.450 L}

= 4 mol/L

Therefore 4 mol/L is the molar concentration.

Answer:

becuz they have protien inside them dumy its easy

Answer:

because they have protein inside them dummy its easy therefore they did not have sugar

Explanation:

The scientific question that can be answered through investigation will be:

"Which of the four types of macromolecules, and in which proportions, are present in the food sample?"

A scientific question is a question that may lead to a hypothesis and help us in. answering (or figuring out) the reason for some observation.

A scientific question simply means a question where a researcher designs a question in order to get an answer to a particular investigation.

According to this question,

Since the researcher wants to know the person responsible for the classroom good mess by determining which macromolecules are present in the mystery food sample, then the question will be "Which of the four types of macromolecules, and in which proportions, are present in the food sample?"

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