Which of the following is an example of frontier research?
A. Investigating how organisms are made of cells.
B. Testing the electrical resistance of different materials.
C. Discovering the nature of dark matter.
D. Researching how animals on the Great Plains interact.

Answer:

Because it's not soluble in water, need to be heated acidic solution

Explanation:

Calcium Fluoride Formula: CaF2  Comprises of Ca2+ and F−

H2O = Water H+ O2- OH-

Insoluble in water

In order to dissolve a salt, you have to break apart the ions and hydrate them via a solvent.

Need to read

HSAB concept( Pearson acid-base concept) is an initialism for "hard and soft (Lewis) acids and bases"

So F- is a Halogen which is a Hard Base

And OH- is a Hard base as well

And H- is a soft base

So soft acids react best with soft bases and hard acids react best with hard bases.

Bases don't react with other bases.

Answer:

molecular formula of liquid = C₈H₁₈

Explanation:

First we determine the empirical formula of the liquid:

Number of moles of each element present in the liquid = % mass / molar mass

For Carbon, (molar mass = 12.01 g/mol) : 84.2/12.01 =7.011 moles

For Hydrogen (molar mass = 1.01 g/mol) : 15.8/1.01 = 15.643

Simplest mole ratio of the elements, C : H  is given by:

C = 7.011/7.011 = 1.0

H = 15.643/7.011 = 2.23

Multiplying through with 5, C:H = 5:11

Therefore, empirical formula is C₅H₁₁

The molecular mass of the liquid is next determined:

Using PV = nRT to find the number of moles of the liquid present

P = 5.0 atm; V = 568.0 mL = 0.568 L; R = 0.082 L*atmmol⁻¹ K⁻¹; T = 273 + 120 = 393 K

n = PV/RT = (5*0.568)/0.082*393

n = 0.088 moles

Molar mass of liquid = mass/no of moles = 10.0 g/ 0.088 moles = 113.63 gmol⁻¹

Molecular formula = n(empirical formula)

Molar mass of empirical formula, C₅H₁₁ = 71 gmol⁻¹

n = molecular mass/empirical mass = 113.63/71 = 1.6

Therefore, molecular formula =  1.6*(C₅H₁₁) = C₈H₁₈

12,194 L is the answer!

Explanation:

Water has the maximum density at the temperature of 4°Celsius. So, it expands at temperatures higher or lower than 4°C, knowing that at the temperature of -25°C the water can't have a lower volume than the one at 15°C.

Answer:

12, 194 L

That's your answer!!!

Answer:

33.5 g/mol

Explanation:

PV=nRT

(1.40 atm)(8.00 L)=n(0.08206)(295 K)

n=0.463 mol

15.50 g/0.463 mol=33.5 g/mol

[tex]empirical \: formula \\ = CaSiO3 \\ please \: see \: the \: attached \: picture \\ hope \: it \: helps[/tex]

Answer:

a)0.765 g

b)7.613 g

c)0.20 L

Explanation:

Consider the reaction involved;

Na(s) + HNO3(aq) ----> NaNO3(s) + H2(g)

Note that, if a hot, saturated aqueous solution of sodium nitrate was allowed to cool, solid sodium nitrate would crystallise out of the solution and this would also be classed as a precipitate. This is the case here.

Number of moles of sodium reacted= mass of sodium reacted/ molar mass of sodium

Number of moles of sodium= 7.85g/23gmol-1

Number of moles of sodium= 0.34 moles of sodium

Number of moles of acid reacted= concentration of acid × volume of acid

Number of moles of acid= 0.0450 × 200/1000

Number of moles of acid= 9×10^-3 moles

Therefore, HNO3 is the limiting reactant.

1 mole of HNO3 yield 1 mole of NaNO3

9×10^-3 moles of HNO3 yield 9×10^-3 moles of NaNO3

Hence mass of NaNO3= number of moles × molar mass

Mass of NaNO3= 9.0×10^-3 moles × 84.9947 g/mol

Mass of NaNO3= 0.765 g of NaNO3

b)

Since

1 mole of sodium metal reacts with 1 mole of HNO3

9×10^-3 moles of sodium reacts with 9×10^-3 moles of HNO3

Therefore amount of unreacted sodium metal = 0.34 moles - 9×10^-3 moles = 0.331 moles

Mass of unreacted sodium metal = 0.331 moles × 23 gmol-1= 7.613 g

c)

If 1 mole of HNO3 yields 1 mole of hydrogen gas

9×10^-3 moles of HNO3 yields 9×10^-3 moles of hydrogen gas.

1 mole of hydrogen gas occupies 22.4 L

9×10^-3 moles of hydrogen gas will occupy 9×10^-3 moles × 22.4/1 = 0.20 L

Answer:

C- 0.25mol/L

Explanation:

Hcl+Naoh-Nacl+H2O

Ratio =1:1

0.2moles of Naoh in1000cm3 what about 25=(25×0.2)÷1000=

0.005moles

0.005moles in 20cm³ what about in 1000

(0.005×1000)÷20=0.25mol/L

According to the molar concentration, the concentration of the acid is 2.5 mole/liters.

Molar concentration is defined as a measure by which concentration of chemical substances present in a solution are determined. It is defined in particular reference to solute concentration in a solution . Most commonly used unit for molar concentration is moles/liter.

The molar concentration depends on change in volume of the solution which is mainly due to thermal expansion. Molar concentration is calculated by the formula, molar concentration=mass/ molar mass ×1/volume of solution in liters.

In terms of moles, it's formula is given as molar concentration= number of moles /volume of solution in liters.In case of 2 solutions, molar concentration is obtained as M₁V₁=M₂V₂, on substitution of values, M₁=25×0.20/20=2.5 mole/L.

Thus,the concentration of the acid is 2.5 mole/liters.

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Answer:

the answer is stratosphere.

about 90% of ozone is found in the stratosphere.

Answer:

The answer is A

Explanation:

The earth naturally maintains the heat energy balance by absorbing a sufficient amount of sunlight energy by the terrestrial land and then reverting back the excess sunlight energy back to the space. The increase in abundance of greenhouse gases in the atmosphere results in absorption of sunlight energy which contains infrared photons this is responsible for increasing the global temperature levels hence, responsible for global warming. These infrared photons are reflected to the earth surface instead of sending back to the space. This is responsible for disturbing the heat balance.

Greenhouse gases interact with infrared photons and reflect them back to earth’s surface, hence option A is correct.

The burning of fossil fuels, logging of forests, and raising of livestock all have a rising impact on the climate and temperature of the planet.

This increases the greenhouse effect and causes global warming by adding a significant amount of greenhouse gases to those that are already present in the atmosphere.

The earth naturally maintains the balance of heat energy by receiving enough solar energy through the terrestrial land and then returning any excess energy to space.

Therefore, greenhouse gases such as CO₂ and N₂O interact with infrared photons and reflect them back to earth’s surface.

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Answer:

OPTION 2 SOLID>LIQUID>GAS

Explanation:

because the inter molecular forces are the strongest in the solid than in liquid and than in gas

Answer:

[tex][N_2]_{eq}=0.094M[/tex]

[tex][O_2]_{eq}=0.094M[/tex]

[tex][NO]_{eq}=0.002M[/tex]

Explanation:

Hello,

In this case, for the given chemical reaction, we write the following law of mass action:

[tex]Keq=\frac{[N_2][O_2]}{[NO]^2}[/tex]

That in terms of the change [tex]x[/tex] due to the reaction extent (ICE procedure) we can write:

[tex]Keq=\frac{x*x}{([NO]_0-2x)^2}[/tex]

Thus, the initial concentration of nitrogen monoxide is:

[tex][NO]_0=\frac{0.570mol}{3.0L} =0.19M[/tex]

Thereby, we write:

[tex]2400=\frac{x*x}{(0.19-2x)^2}[/tex]

That we can solve by suing the quadratic equation formula or solver to obtain two roots:

[tex]x_1=0.094M\\x_2=0.096M[/tex]

Nevertheless, the correct answer is 0.094 M since the other root will produce a negative concentration of nitrogen monoxide at equilibrium, therefore, the equilibrium concentrations turn out:

[tex][N_2]_{eq}=x=0.094M[/tex]

[tex][O_2]_{eq}=x=0.094M[/tex]

[tex][NO]_{eq}=0.19M-2x=0.19M-2(0.094M)=0.002M[/tex]

Best regards.

Answer:

True

Explanation:

Because Nitric acid is formed by the gas-phase hydrolysis of N2O5. The energy profile curve for the reaction N2O5 H2O → 2HNO3 is shown here. The reaction is endothermic and the activation energy of the reverse reaction is larger than for the forward reaction.

Answer:

2O L

Explanation:

The balanced chemical equation is 2NO+O  

2

​  

→2NO  

2

​  

Thus, 2 moles of NO will produce 2 moles of NO  

2

​  

.

Also, the volume is directly proportional to the number of moles.

Therefore, 20 L of NO will produce 20×  

2

2

​  

=20 L of NO  

2

​  

Answer:

El potencial celular estándar, [tex]E_{cell}[/tex] is +0.46 V

Explanation:

Las reacciones de media célula son;

Media reacción del ánodo Cu²⁺ + 2e⁻ ↔ Cu, E ° = 0.34 V

Media reacción catódica 2Ag + 2e⁻ ⁻ 2Ag, E ° = 0.80 V

Sin embargo tenemos para hierro Fe²⁺ + 2e⁻ ↔ Fe, E ° -0.44 V

y Fe³⁺ + e⁻ ↔ Fe²⁺, E ° = 0.77 V

 que es más alta que la del cobre presente, por lo tanto, el cobre se oxidará en el ánodo

Por lo tanto, en el ánodo, tendremos

Cu → Cu²⁺ + 2e⁻ (E ° = -0.34 V)

En el cátodo

2Ag + 2e⁻ → 2Ag (E ° = 0.80 V)

[tex]E_{cell} = E_c + E_a = -0.34 + 0.8 = +0.46 \, V[/tex]

El potencial celular estándar, [tex]E_{cell}[/tex] = +0.46 V

Answer:

pH value test can be used to demonstrate that NaOH is a stronger alkali than NH3

Explanation:

pH value test can be used to demonstrate that NaOH is a stronger alkali than NH3. This is done by measuring the same volume of equal concentration of hydroxide and ammonia. A glass rod was dipped into 0.2 M of sodium hydroxide and 0.2 M of ammonia, each drop of solution was then placed on a pH paper matched with a color chart and the pH value was recorded.

The result showed that sodium hydroxide being a strong alkali would dissociate completely in aqueous solution thereby having a higher pH while ammonia would dissociate slightly/partially in aqueous solution thereby having a lower pH value

Answer:

Galileo: "Father of Modern Science."

Aristotle: Geocentric theory." (The planests revolves around the earth.)

Torricelli: Invented the barometer. (An instrument which measures pressure.)

Copernicus: Heliocentric theory. (Aka, the planets revolves around the sun.)

Vesalius: Examined the inner workings of the human body

Newton: Developed law of universal gravitation.

Nightingale: Founded nursing profession.

Celsius: Developed metric temperature scale

I hope this helps! Thanks:)

Answer:

metals donate electrons to nonsmetals

Answer:

Strontium, a group 2 element with an electron configuration of 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² , will form a +2 ion in a chemical bond.

Explanation:

An ionic bond is produced between metallic and non-metallic atoms, where electrons are completely transferred from one atom to another. During this process, one atom loses electrons and another one gains them, forming ions. Usually, the metal gives up its electrons forming a cation to the nonmetal element, which forms an anion.

So an ion is an atom or group of atoms that have an electric charge. A cation is an ion that has a positive charge.

The alkali metals in the earth (Elements IIA) lose two electrons to form a 2+ cation. Strontium is an alkali metal that loses the two electrons belonging to 5s², forming the +2 ion.

Answer:

+2

Explanation:

Answer:

C. pH > pOH; Kw = 1.0 * 10^-14

Explanation:

The ion product of water, Kw = [H+]*[OH-] = 1.0 * 10^-14. It is a constant.

When an acid or base is added to water, its ion product does not change as it a constant. However, the relative concentrations of H+ ions and OH- ions will change depending on whether an acid or base is added to water.

When an acid is added to water, the concentration of H+ ions increases while that of OH- ions decreases, and vice versa.

Therefore, in the above situation where an acid is added to water, pH > pOH; Kw = 1.0 * 10^-14

Answer:

It continuously decreases.

Answer:

39

Explanation:

Total protons + total neutrons = mass number

Answer:

[tex]\large \boxed{1.615 \times 10^{25}\text{ molecules water}}[/tex]

Explanation:

You must calculate the mass of the water, convert it to moles, and then calculate the number of molecules.

1. Mass of water

[tex]\text{Mass } = \text{499.8 mL} \times \dfrac{\text{0.967 g}}{\text{1 mL}} = \text{483.3 g}[/tex]

2. Moles of water

[tex]\text{Moles of water} = \text{483.3 g water} \times \dfrac{\text{1 mol water}}{\text{18.02 g water}} = \text{26.82 mol water}[/tex]

3. Molecules of water

[tex]\text{No. of molecules} = \text{26.82 mol water} \times \dfrac{6.022 \times 10^{23}\text{ molecules water}}{\text{1 mol water}}\\\\= \mathbf{1.615 \times 10^{25}}\textbf{ molecules water}\\\text{The sample contains $\large \boxed{\mathbf{1.615 \times 10^{25}}\textbf{ molecules water}}$}[/tex]

The number of molecules of water  present in the bottle is 1.62×10²⁵ molecules.

We'll begin by calculating the mass of the water in the bottle.

Mass = Density × Volume

Mass of water = 0.967 × 499.8

Mass of water = 483.3066 g

Finally, we shall determine number of molecules of water in the bottle.

From Avogadro's hypothesis,

1 mole of water = 6.02×10²³ molecules

But,

1 mole of water = 18 g

Thus, we can say that:

18 g of water = 6.02×10²³ molecules

Therefore,

483.3066 g of water = (483.3066 × 6.02×10²³) / 18

483.3066 g of water = 1.62×10²⁵ molecules

Thus, the number of molecules of water in the bottle is 1.62×10²⁵ molecules.

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Explanation:

They allow the bonds between oxygen and hydrogen to be single. They increase the partial positive charge on the oxygen atom. They counter the uneven pull on electrons between the atoms.

Answer:

Substance E does not conduct electricity in both solid and molten states because of very low melting and boiling points.

In both solid and molten state free electrons are required to conduct electricity. substance E has low boiling and melting point which means substance will have relatively weak bonds. Because of weak bonds substance E might not have much free electron in its outermost shell that can cause the electric current by their coordinated movement.

Hence, substance E is unable to conduct in both melting and molten state.

Answer:

1. 1.72 moles of potassium.

2. All of the answers are true

3. Are used up during a reaction

Explanation:

Recall that the number of moles is obtained from;

Number of moles= Mass of potassium/ molar mass of potassium

Mass of potassium= 67 g

Molar mass of potassium= 39 gmol-1

Number of moles of K= 67 g/ 39 gmol-1

Number of moles = 1.72 moles of potassium.

2. When we look at all the options, we will realize that all the options are true. The rate of reaction doubles for each 10°C rise in temperature, increasing reactant concentration increases particle collision and ultimately increases the rate of reaction. Rate of reaction deals with rate of disappearance of reactants or rate of appearance of products.

3. Catalysts remain unchanged in a chemical reaction because they do not actually participate in the reaction. Hence they are not used up in any chemical reaction.

Answer:

Dmitri Mendeleev

Explanation:

He was a Russian Scientist who decided to reorganize the periodic table after other notable scientists such as Antoine-Laurent Lavoisier had also tried to organize it based on the states of matter of the elements.

Mendeleev reorganized the period in the order of increasing atomic mass although there were some other modifications by modern scientists.

Answer: C

Explanation:

A P E X

The VSEPR theory predicts the shape and molecular geometry of the molecule.

Molecular geometry can be defined as a three -dimensional arrangement of atoms which constitute the molecule.It includes parameters like bond length,bond angle and torsional angles.

It influences many properties of molecules like reactivity,polarity color,magnetism .The molecular geometry can be determined by various spectroscopic methods and diffraction methods , some of which are infrared,microwave and Raman spectroscopy.

They provide information about geometry by taking into considerations the vibrational and rotational absorbance of a substance.Neutron and electron diffraction techniques provide information about the distance between nuclei and electron density.

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Answer:

2Cl- ⇒ Cl ↓2+ 2e

Explanation: sorry if this is not what you were looking for.