Why do scientists use the scientific method?
A. It helps them do research that other scientists can understand.
B. It helps them ask questions that affect as many people as
possible.
C. It helps them make sure a certain question has not been asked
before.
OD. It helps them determine whether an idea is supported by evidence.
Help

Answers

Answer 1

Answer:

D

Explanation:

It helps determine whether an idea is supported by evidence

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Related Questions

most naturally occurring oxygen is

Answers

Naturally occurring oxygen is composed of three stable isotopes, 16O, 17O, and 18O, with 16O being the most abundant (99.762% natural abundance).

Which of the following statements is correct concerning the class of reactions to be expected for benzene and cyclooctatetraene?
A) Both substances undergo addition reactions.
B) Both substances undergo substitution reactions.
C) Benzene undergoes addition; cyclooctatetraene undergoes substitution.
D) Benzene undergoes substitution; cyclooctatetraene undergoes addition.

Answers

Answer:

Both substances undergo substitution reactions.

Explanation:

Let us go back to the idea of aromaticity. Aromatic substances are said to possess (4n + 2) π electrons according to Huckel rule.

Aromatic substances are unusually stable and the aromatic ring can not be destroyed by addition reactions.

Since both benzene and cyclooctatetraene are both aromatic, they do not undergo addition reactions whereby the aromatic ring is destroyed. They both undergo substitution reaction in which the aromatic ring is maintained.

Suppose that you add 24.3 g of an unknown molecular compound to 0.250 kg of benzene, which has a K f of 5.12 oC/m. With the added solute, you find that there is a freezing point depression of 3.14 oC compared to pure benzene. What is the molar mass (in g/mol) of the unknown compound

Answers

Solution :

We know that :

[tex]$\Delta T_f = k_f.m$[/tex]  and   [tex]$m=\frac{w_2}{m_2 \times w_1}$[/tex]

Then, [tex]$\Delta T_f = k_f.\frac{w_2}{m_2.w_1}$[/tex]   ..................(1)

Where,

[tex]w_1[/tex] = amount of solvent (in kg)

[tex]w_2[/tex] = amount of solute (in kg)

[tex]m_2[/tex] = molar mass of solute (g/mole)

[tex]m[/tex] = molality of solution (mole/kg)

Given :

[tex]\Delta T_f[/tex] = [tex]3.14\ ^\circ C[/tex],   [tex]k_f= 5.12\ ^\circ C/m[/tex]

                              [tex]=5.12 \ ^\circ C/mole/kg[/tex]

                              [tex]=5.12 \ ^\circ C \ kg/mole[/tex]

[tex]w_1[/tex] = 0.250 kg,  [tex]w_2[/tex] = 24.3 g

Then putting this values in the equation is (1),

[tex]$3.14 = \frac{5.12 \times 24.3}{m_2 \times 0.250}$[/tex]

[tex]$m_2 = \frac{5.12 \times 24.3}{3.14 \times 0.250}$[/tex]

[tex]m_2= 158.49[/tex]  g/mole

So, the molar mass of the unknown compound is 158.49 g/mole.

Why does nitrogen not show allotropy?​

Answers

Answer:

Nitrogen does not show allotropy because of its small size and high electronegativity. The single N-N bond is weaker than P-P bond because of high inter electronic repulsions among non-bonding electrons due to the small bond distance. Hence it does not show allotropy.

Answer:

The nitrogen atom has short inter-bond distance, hence highly electronegative in terms of magnitude. This creates no relation in energy varieties hence no allotropes formed.

Nitrogen atom is also very small.

A saturated solution of potassium iodide contains, in each 100 mL, 100 g of potassium iodide. The solubility of potassium iodide is 1 g in 0.7 mL of water. Calculate the specific gravity of the saturated solution

Answers

Answer:

Specific gravity of the saturated solution is 2

Explanation:

The specific gravity is defined as the ratio between density of a solution (In this case, saturated solution of potassium iodide, KI) and the density of water. Assuming density of water is 1:

Specific gravity  = Density

The density is the ratio between the mass of the solution and its volume.

In 100mL of water, the mass of KI that can be dissolved is:

100mL * (1g KI / 0.7mL) = 143g of KI

That means all the 100g of KI are dissolved (Mass solute)

As the volume of water is 100mL, the mass is 100g (Mass solvent)

The mass of the solution is 100g + 100g = 200g

In a volume of 100mL, the density of the solution is:

200g / 100mL = 2g/mL.

The specific gravity has no units, that means specific gravity of the saturated solution is 2

Why U.S. genetically modified ingredients ruin the taste

Answers

Answer:

I hope this helps!

Explanation:

The biggest threat caused by GM foods is that they can have harmful effects on the human body. It is believed that consumption of these genetically engineered foods can cause the development of diseases which are immune to antibiotics. ... As the health effects are unknown, many people prefer to stay away from these foods.

Write the complete ground-state electron configuration of I⁻.

Answers

Explanation:

here's the answer to your question

Iodine's neutral atom has the following electronic configuration: 1 s² 2 s² 2 p⁶ 3 s² 3 p⁶ 4 s² 3 d¹⁰ 4 p⁶ 5 s² 4 d¹⁰ 5 p⁵. The complete ground-state electron configuration of I⁻ is  [Kr]5s² 4d¹⁰ 5p⁶.

What is electronic configuration?

Electronic configuration is defined as each electron moves individually within an orbital while being surrounded by an average field produced by all other orbitals. The electron configuration is used to describe an atom's ground state orbitals, but it may also be used to depict an atom that has ionized into a cation or anion by making up for any lost or gained electrons in the orbitals after it.

The ground state electronic configuration is defined as the configuration of lower energy electrons surrounding an atom's nucleus. Ground state is defined as the least energetic state feasible for a physical system.  It is important because permits us to determine the location of the excited electrons' departure and return when they release a photon.

Thus, iodine's neutral atom has the following electronic configuration: 1 s² 2 s² 2 p⁶ 3 s² 3 p⁶ 4 s² 3 d¹⁰ 4 p⁶ 5 s² 4 d¹⁰ 5 p⁵. The complete ground-state electron configuration of I⁻ is  [Kr]5s² 4d¹⁰ 5p⁶.

To learn more about electronic configuration, refer to the link below:

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Draw the organic product(s) of the following reaction.

NaNH2/ NH3(l)
CH2CH2CH2-Câ¡C -C-H â

Answers

Answer:

H-C = C-H NaNH2 [tex]\ \to \0}[/tex] H-C = CNa

H-C = C - CH2 CH2 CH2 CH3

Explanation:

NaNH2 acts as base in this reaction. The organic products released after the reaction of carbon hydrogen atom with sodium amide. These products released after the chemical reaction when carbon and hydrogen atom reacts and NaNH2 acts as base then substitution nucleophilic reaction takes place.

5. For Sodium, the Work Function is listed as 2.75 eV but the Ionization Energy is listed as 5.14 eV. Is one of the experiments wrong? Give a possible explanation as to this difference in the minimum energy needed to eject or free an electron from Sodium.

Answers

Answer:

See explanation

Explanation:

The work function of a metal is defined as that minimum energy which is required to remove one electron from the surface of a metal when it is irradiated with a photon of light. The work function is different for different metals.

The ionization energy of a metal is the energy required to remove an electron from an atom. It depends on the position of the electron within the atom.

The work function specifically refers to the energy required to remove an electron from the conduction band of a metal. Hence, the work function is always lower than the ionization energy.

A buffer is a solution that is a mixture of either a weak acid and its conjugate base or a weak base and its conjugate acid. When strong acids or strong bases are added, buffers either accept protons when they are in excess or donate protons when they have been depleted to minimize changes in pH. Which of the statements correctly describe the properties of a buffer?

a. The conjugate base of an acidic buffer will accept hydrogen protons when a strong acid is added to the solution.
b. An acidic buffer solution is a mixture of a weak acid and its conjugate base.
c. An acidic buffer solution is a mixture of a weak base and its conjugate acid.
d. The weak acid of an acidic buffer will accept hydrogen protons when a strong base is added to the solution.
e. The weak acid of an acidic buffer will donate hydrogen protons when a strong base is added to the solution.
f. The conjugate base of an acidic buffer will donate hydrogen protons when a strong acid is added to the solution.

Answers

Answer:

a. The conjugate base of an acidic buffer will accept hydrogen protons when a strong acid is added to the solution.

b. An acidic buffer solution is a mixture of a weak acid and its conjugate base.

e. The weak acid of an acidic buffer will donate hydrogen protons when a strong base is added to the solution.

Explanation:

Which of the statements correctly describe the properties of a buffer?

a. The conjugate base of an acidic buffer will accept hydrogen protons when a strong acid is added to the solution. TRUE. The conjugate base neutralizes the excess of hydrogen protons.

b. An acidic buffer solution is a mixture of a weak acid and its conjugate base. TRUE.

c. An acidic buffer solution is a mixture of a weak base and its conjugate acid. FALSE. This is a basic buffer solution.

d. The weak acid of an acidic buffer will accept hydrogen protons when a strong base is added to the solution. FALSE. The weak acid will react with the hydroxyl ions from the added base.

e. The weak acid of an acidic buffer will donate hydrogen protons when a strong base is added to the solution. TRUE. These hydrogen protons will form water.

f. The conjugate base of an acidic buffer will donate hydrogen protons when a strong acid is added to the solution. FALSE. It will accept hydrogen protons.

Write chemical equations and corresponding equilibrium expressions for each of the two ionization steps of carbonic acid. Part A Write chemical equations for first ionization step of carbonic acid. Express your answer as a chemical equation. Identify all of the phases in your answer.

Answers

Solution :

[tex]H_2CO_3[/tex] is considered a diprotic acid.

Sp it can dissociate in solution by giving two protons.

Chemical equations for the first step of carbonic acid is :

First ionization

[tex]$H_2CO_3(aq) + H_0(1) \rightleftharpoons H_.O^+(aq) + HCO_3^-(aq)$[/tex]

Equilibrium constant expression is

[tex]$K_{a}_{1}=\frac{[H_3O^+][HCO_3^-]}{[H_2CO_3]}$[/tex]

Second ionization -

[tex]$HCO_3^-(aq) + H_2O(l) \rightleftharpoons H_3O^+(aq) + CO_3^{2-}(aq)$[/tex]

Equilibrium constant expression is

[tex]$K_{a2}=\frac{[H_3O^+][CO_3^{2-}]}{[HCO_3^-]}$[/tex]

Complete the sentences by identifying the correct missing words. Alph and beta particles originate from the Choose... . Protection from radiation is necessary because if radiation passes through the body it can damage Choose... . Exposure to radiation can be limited by increasing the Choose... from the radioactive source.

Answers

Answer:

Alpha and beta particles originate from the nucleus, protection from radiation is important because if the radiation passes through the body it can damage cells. Exposure to radiation is often limited by increasing the distance from the radioactive source.

Explanation:  

Alpha and beta particles come from unstable atoms during their decay.  This radiation is extremely harmful which may damage DNA, causing a high rate of mutation.  If we increase the distance of the source of radioactive exposure we will prevent damage.

The standard free energy that is required for the sodium-potassium ATPase to pump two K ions into the cell and three Na ions is 43.8 kJ/mol but the standard free energy change of hydrolysis of ATP is only -32 kJ/mol. This apparent imbalance of free energy can be accounted for because ________.

Answers

Answer:

Explanation:

This apparent disparity of the free energy can be taken into account because:

the free energy produced by the hydrolysis of one ATP is adequate enough under psychological circumstances.

The Na-K ATPase aids the pumping of Na+ ions out of the cell and K+ ions into the cell. These actions occurring against their potential(concentration) gradients, which may be produced by hydrolyzing one ATP molecule.

Sodium acetate

NaC2H3O2

SC2H3O2

Na2C2H3O2

Answers

Answer:

Sodium acetate is NaC2H3O2

Answer:

The answer is A for the lazy people.

describe briefly the laboratory preparation of methane gas​

Answers

Answer:

In the laboratory, methane is formed by heating sodium ethanoate with a mixture of sodium hydroxide and calcium oxide, called soda lime, on heating in the presence of a catalyst, calcium oxide, the -COONa group from sodium ethanoate is replaced by the hydrogen atom from sodium hydroxide, forming methane and sodium

Explanation:

What volume of each solution contains 0.14 mol of KCl? Express your answer using two significant figures.
1.8 M KCl

Answers

Answer:

Solution given:

1 mole of KCl[tex]\rightarrow [/tex]22.4l

1 mole of KCl[tex]\rightarrow [/tex]74.55g

we have

0.14 mole of KCl[tex]\rightarrow [/tex]74.55*0.14=10.347g

74.55g of KCl[tex]\rightarrow [/tex]22.4l

10.347 g of KCl[tex]\rightarrow [/tex]22.4/74.55*10.347=3.11litre

volume of each solution contains 0.14 mol of KCl contain 3.11litre.

[tex]\:[/tex]

1 mole of KCl → 22.4l

1 mole of KCl → 74.55g

we have

0.14 mole of KCl → 74.55*0.14=10.347g

74.55g of KCl  → 22.4l

10.347 g of KCl → 22.4/74.55*10.347=3.11litre

volume of each solution contains 0.14 mol of KCl contain 3.11litre.

12 grams of carbon is burnt with a certain amount of air containing 36 grams of oxygen. The product contains 24 grams of Co, and 4 grams of CO. Calculate the percentage of excess oxygen.

Answers

Answer:

C

Oxygen gas is limiting.

C(s) + O

2

→CO

2

(g)

No. of moles of carbon =

12

36

=3 moles

No. of moles of oxygen =

32

32

=1 moles

So, 2 moles of carbon is left and oxygen will be completed.

So, O

2

is limiting reagent.

Answer:

14.5

Explanation:

not sure how I got it but I hope this helped!

8. Build a neutral lithium atom.
Now, what must you do to make the lithium atom's charge change to +1?
Hint: Lithium is atomic number 3.
Add 2 electrons
Remove 1 electron
Add 1 electron
Add 1 proton

Answers

Answer:

Remove 1 electron

Explanation:

In the atom of each element, there are three subatomic particles viz: proton, neutron and electron. The number of proton (positively charged) and electron (negatively charged) determines the charge of that element. The more the proton, the more positively charged an ion is and vice versa for electron.

According to this question, a neutral atom of lithium (Li) with atomic no. 3 is given i.e. a lithium atom with charge 0. To make the lithium atom's charge change to +1, ONE ELECTRON MUST BE REMOVED OR LOST.

Note that, the proton number (atomic number) of an element does not change, rather the electron number changes in relation to the no. of protons.

convert 14.72 kg to ____ mg

Answers

Answer:

14720000

Explanation:

1 kg = 1000000 mg

14.72 kg = 14.72 x 1000000

=14720000

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Which are the following exothermic or endothermic

Absorbs Energy

-Hrxn

+Hrxn

Feels Hot

Heat flows from surrounds to Reaction

Not Energetically Favorable

Energetically Favorable

Releases Energy

Feels Cold

Heat flows from the reaction to the surrounds

Answers

Answer:

Explanation:

Your mom

Wet helium gas is placed into a balloon at 24.4 degrees Celsius and a pressure of 765.3 mm Hg. What volume (in L) does the dry gas occupy if the water vapor pressure is 24.3 torr and the mass of dried helium gas in the balloon is 0.498 g

Answers

Answer:

Hence the Volume of Gas = 3.04 L.

Explanation:  

pressure of dry gas = 765.3 - 24.3 = 741 mmhg  

Temperature of gas = 24.4+273.15 = 297.55 k  

No of mol of gas = 0.498/4 = 0.1245 mol  

R = gas constant = 0.0821 l.atm.k-1.mol-1  

From ideal-gas equation

PV = nRT  

(741/760) x v = 0.1245 x 0.0821 x 297.55  

V = Volume of Gas = 3.04 L

Define pressure. Group of answer choices force exerted by solids to the surrounding area force used to compress a gas force used to melt a solid force exerted per unit area by gas particles as they strike the surfaces around them force applied to a gas to condense it

Answers

Answer:

force exerted per unit area by gas particles as they strike the surfaces around them

Explanation:

According to the kinetic molecular theory, a gas is composed of molecules. The molecules of a gas are in constant random motion and collide frequently with each other as well as with the walls of the container.

Pressure is defined as force per unit area. The pressure of a gas is the force exerted per unit area by gas particles as they strike the surfaces around them hence the answer above.

The reaction A + B <-------> C + D has been studied at five widely different temperature and the equilibrium tabulated.
Equilibrium constant K (at varies temperatures)
K at T1 1 x 10^-2
K at T2 2.25
K at T3 1.0
K at T4 81
K at T5 4 x 10^1
Which temperature is the products favored?

Answers

If K is greater than 1, then products are favored

The structure of the compound CuI is best described as a cubic closest packed array of iodide ions with the copper ions in tetrahedral holes. What percent of the tetrahedral holes are occupied in this solid

Answers

Answer:

12.5 %

Explanation:

In CCP, the effective number of anion is 4

That is there are 4 I- present in 1 unit cell

Number of tetrahedral void = 2*effective number of anion

= 2*4

= 8

In ZrI4, for every 4 anion, there are only 1 Zr atom.

So, one tetrahedral void is occupied per unit cell out of 8

% tetrahedral void occupied = 1*100/8

= 12.5 %

Answer: 12.5 %

draw styrene

draw the structure of cyrene ​

Answers

the correct answer is the second option

Which of the following statements is/are correct? 1. There are 5 orbitals in
the d subshell. 2. The d orbitals can accommodate 14 electrons. 3. The first
shell contains s and p orbitals. 4. The s orbital can accommodate 2 electrons.

A. 1 and 4
B. 2 and 3
C. 3 and 4
D. 2 and 4

Answers

?? Como dices entonces hablas english

Question 6 of 30
What is the balanced equation for the redox reaction between silver and nitric
acid (HNO3) that forms nitrogen dioxide and silver ions?
A. Ag + 2H+ + NO3
-
NO2 + Ag+ + H20
0
B. Ag + 2NO3 → 2NO2 + Ag+ + O2
C. Ag + 2H+ HNO3 → NO2 + Ag+ H2O + 2e
D. Ag + NO3
NO2 + Agt + e

Answers

Answer:

its letter c

Explanation:

I hope this help

The reaction of silver and nitric acid is given with the chemical equation as Ag + 2 H⁺ + HNO₃ → NO₂ + Ag⁺ + H₂O + 2e⁻. Thus, option C is correct.

What is a redox reaction?

Redox reaction can be given as the chemical reaction in which one of the reactants is oxidized and the other gets reduced. Oxidation is defined as the loss of electrons and gain of hydrogen, while reduction is defined as the gain of electrons and loss of hydrogen.

The change in the oxidation and reduction changes the oxidation states of the elements, and thereby mediated the formation of a more stable chemical compound.

The reaction of silver with nitric acid forms the release of hydrogen from nitric acid, thereby the compound gets reduced, while with the loss of electrons, the silver gets oxidized.

The chemical equation for the same can be given as:

Ag + 2 H⁺ + HNO₃ → NO₂ + Ag⁺ + H₂O + 2e⁻

Thus, option C is correct.

Learn more about redox reaction, here:

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A sample of Kr gas is observed to effuse through a pourous barrier in 8.15 minutes. Under the same conditions, the same number of moles of an unknown gas requires 4.53 minutes to effuse through the same barrier. The molar mass of the unknown gas is ____________ g/mol.

Answers

Answer:

25.88 g/mol

Explanation:

Graham's law is a famous law which states that the diffusion rate or the effusion rate of any gas varies inversely to the square root of the molecular weight the gas.

So from Graham's law, we have,

[tex]$\frac{\text{time}}{M^{1/2}}=\text{constant}$[/tex]

Using the sample of Kr gas having M = 83.8

[tex]$\frac{8.15}{(83.8)^{0.5}}= \frac{4.53}{M^{0.5}}$[/tex]

[tex]$M^{0.5}= 5.088$[/tex]

M = 25.88 g/mol

A wavelength of 489.2 nm is observed in a hydrogen spectrum for a transition that ends in the nf level of the Balmer series. What was ni for the initial level of the electron

Answers

Answer:

[tex]n_1=4[/tex]

Explanation:

From the question we are told that:

Wavelength [tex]\lambda=489.2 nm =>4.86*10^{-7}[/tex]

nf level= Balmer series

nf level= 2

Generally the equation for Wavelength is mathematically given by

[tex]\frac{1}{\lambda}=R[\frac{1}{nf^2}-\frac{1}{n_1^2}][/tex]

Where

[tex]R=Rydberg Constant[/tex]

[tex]R=1.097*10^7[/tex]

Therefore

[tex]\frac{1}{4.86*10^{-7}}=1.097*10^7[\frac{1}{2^2}-\frac{1}{n_1^2}][/tex]

[tex]n_1=4.0021[/tex]

[tex]n_1=4[/tex]

A strawberry nutritional drink used for a liquid diet is flavored with methyl butanoate. Draw the structure of methyl butanoate.

Answers

Answer:

See explanation and image attached

Explanation:

Methyl butanoate is an ester. Esters have the general molecular formula, RCOOR where the two Rs may represent the same or different alkyl groups.

Methyl butanoate is has a fruity odor, smelling like apples or pineapples fragrance. It is also called methyl butyrate.

The structure of the compound is shown in the image attached to this answer.

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