5. Rosalind Franklin was a key figure in the discovery of the structure of DNA, yet she
was not included in the Nobel Prize which was awarded to Watson and Crick. Carry out
some research to find out how she contributed to this work and use the space below
to write up your findings​

Answer:

Ice (frozen water) is part of the hydrosphere, but it's given its own name, the cryosphere.

The cryosphere is part of the hydrosphere of the Earth system. The correct option is D.

The cryosphere contains all the frozen parts of the earth. The term is made up of the Greek word “krios” which means cold. All the frozen water of the oceans and snow comes under the cryosphere.

The atmosphere contains all spheres, it is an envelope of gases. The geosphere is the land part of the earth, and the biosphere is the part where the living part is present.

The cryosphere is h habitat of many living creatures, and the climate of the earth is highly dependent on this sphere. The warmth of the earth is increasing and the cryosphere part is decreasing day by day, which is having problems for many animals.

Thus, the correct option is D, hydrosphere.

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Answer: 0.28 M ammonia + 0.35 M ammonium nitrate and 0.15 M nitrous acid + 0.14 M potassium nitrite

Explanation:

Buffer solution is the solution which resists the change in the magnitude of the pH when small additions of either acid or base is added.  

Acidic Buffer solutions consist of weak acid and its conjugate base usually mixed in relatively equal and large quantities.

Basic Buffer solutions consist of weak base and its conjugate acid usually mixed in relatively equal and large quantities.

Thus 0.28 M ammonia + 0.35 M ammonium nitrate ( weak base + conjugate acid)  and 0.15 M nitrous acid + 0.14 M potassium nitrite (weak acid + conjugate base)  are good buffer systems

The aqueous solutions that are good buffer systems are:

We want to determine which of the given solutions would make a good buffer.

A buffer is a solution used to resist abrupt changes in pH when an acid or a base is added.

Which of the following aqueous solutions are good buffer systems?

The aqueous solutions that are good buffer systems are:

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Answer:

Around 3.62 degrees kelvin

Explanation:

Assuming this is at STP:

The first step is to convert 2600mL to liters. There are 1000 milliliters in a liter, meaning that this is equal to 2.6L.

Now:

[tex]\dfrac{P_1V_1}{T_1}=\dfrac{P_2V_2}{T_2}\\\\\\\dfrac{196(1)}{273}=\dfrac{2.6(1)}{T_2} \\\\\\T_2\approx 3.62K[/tex]

Hope this helps!

Answer:

Your question is complex, because I think you wrote it wrong.

Although in front of this what I can help you is that the carbons are associated between a single, double or triple union.

This depends on whether they are attached to more or less carbons or hydrogens, the carbons have the possibility of joining 4 radicals, both other carbons and hydrogens.

Simple junctions talks about compound organisms called ALKANS.

The double unions, in organic these compounds are called as ALQUENOS.

And as for the tertiary unions, the organic chemistry names them as ALQUINOS.

These compounds that we write, a simple union, the less energy, the less this union, that is why the triple bond is the one that contains the most energy when breaking or destroying it in a reaction.

Explanation:

In a chemical compound the change of these unions if we modified them we would generate changes even in the classifications naming them as well as different compounds and not only that until they change their properties

Answer:

Answer:

The first should be left asis because carbon already has 4 bonds/8 electrons

The second needs to have a double bond to give carbon 4 bonds/8 electrons

The third must have a triple bong between the carbons to give them both 4 bonds/8 electrons

Explanation:

Make sure Hydrogen only has 1 bond/2 electrons at all times. Carbon needs a total of 4 bonds/8 electrons

Answer:

A. 0.75 moles NO2 are required

B. 82.2 gnof HNO3 are produced

C. 205.3 g of HNO3 are produced

Explanation:

Check attachment below for explanation and calculations

Answer:

140 T or thymine base

Explanation:

Adenine pairs with Thymine in DNA thus the number of adenine will always equal number of thymine (unless some sort of mutation), therefore in this problem you have 140 A so you have 140 T as well. Remember: Adenine (A) and Thymine(T) is equal, & Cytosine (C) and Guanine (G) is equal

Answer:

the volume of the gas at conditions of STP = 151.04998 ml

Explanation:

Data given:

V1 = 180 ml

T1 = 35°C or 273.15 + 35 = 308.15 K

P1 = 95.9 KPa

V2  =?

We know that at STP

P2 = 1 atm or 101.3 KPa

T2 = 273.15 K

At STP the pressure is 1 atm and the temperature is 273.15 K

applying Gas Law:

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

putting the values in the equation of Gas Law:

[tex]V_2=\frac{P_1V_1T_2}{T_1P_2}[/tex]

V_2 =[tex]\frac{95.9\times180\times273.15}{308.15\times101.3}[/tex]

V2 = 151.04998

therefore, V2 = 151.04998 ml

Answer:

151 mL is the correct answer to the given question .

Explanation:

We know that

[tex]PV =n RT[/tex]

Where P =pressure ,V=volume and T=Temperature

Given

P=95.9 kPa.

V=[tex]180 * 10 ^{-3}[/tex]

R=25/3

T=273 + 35 =308k

Putting these value into the equation we get

[tex]95.9\ * 180\ *\ 10^{-3} \ =\ n * \frac{25}{3} * 308[/tex]

n=[tex]6.72 * 10^{-3}[/tex]

Now using the equation

[tex]n= \ \frac{V}{22.4}[/tex]

[tex]6.72 * 10^{-3} =\frac{V}{22.4}\\ V\ =\ 150.6mL[/tex]

This can be written as  151mL

Answer:

218.3 g/mol

Explanation:

Boiling point elevation occurs when a solute is added to a solvent increasing the boiling point of the solution with regard to the pure solvent.

The law is:

ΔT = Kb×m×i

Where ΔT is change in temperature (3.67°C), Kb is the boiling point constant of the solvent (4.95°C/m), m is molality of the solution and i is Van't Hoff factor (1 for a non-electrolyte).

3.67°C = 4.95°C/m×m×i

0.7414m = molality of the solution (Moles solute / kg solvent).

As the mass of the solvent is 50.0g = 0.0500kg:

0.7414m = Moles solute / 0.0500kg

0.0371 = moles of solute

As the mass of the solute is 8.1g, molar mass of the solute (Ratio between mass in g and moles) is:

8.1g / 0.0371mol =

Answer:

0.912 L or 912 mL

Explanation:

 M(KClO3) =  122.55 g/mol

3.00 g KClO3 * 1  mol/122.55 g = 3.00/122.55 mol =0.02449 mol                

                           2KCIO3(s)=2KCI(s) + 3O2(g)

from reaction      2 mol                         3 mol

given                   0.02449 mol              x

x = 0.02449*3/2 =0.03673 mol O2

T = 24 + 273.15 = 297.15 K

PV = nRT

V= nRT/P = (0.03673 mol*0.082057 L*atm/K*mol*297.15 K)/0.982 atm =

= 0.912 L or 912 mL

Answer:

H2 consumed 4.22 mol

N2 produced 59.107 g

Explanation:

Balanced equation:

2NO (g) + 2H2 (g) N2 (g) + 2H2O (l)

H2O MW = 18.02 g/mol

N2 MW = 28.01 g/mol

To determine the moles of H2O produced, the following formula should be used:

[tex]MW=\frac{mass}{mol}[/tex]

The value of moles is cleared:

[tex]mol=\frac{mass}{MW} =\frac{76.2g}{18.02\frac{g}{mol} } =4.22 mol[/tex]

2 mol H2      ⇒ 1 mol N2

4.22 mol H2 ⇒ X

[tex]X=\frac{4.22mol*1 mol}{2 mol} =2.11 mol[/tex]

To calculate the mass of H2 consumed, the molecular weight equation is used again:

[tex]mass=MW*mol=28.013\frac{g}{mol}*2.11mol=59.107g[/tex]

Answer:

ΔH of the reaction is -802.3kJ.

Explanation:

Using Hess's law, you can know ΔH of reaction by the sum of ΔH's of half-reactions.

Using the reactions:

(1) Cgraphite(s)+ 2H₂(g) → CH₄(g) ΔH₁ = −74.80kJ

(2) Cgraphite(s)+ O₂(g) → CO₂(g) ΔH₂ = −393.5k J

(3) H₂(g) + 1/2 O₂(g) → H₂O(g) ΔH₃ = −241.80kJ

The sum of (2) - (1) produce:

CH₄(g) + O₂(g) → CO₂(g) + 2H₂(g) ΔH' = -393.5kJ - (-74.80kJ) = -318.7kJ

And the sum of this reaction with 2×(3) produce:

CH₄(g) + 2 O₂(g) → CO₂(g) + 2H₂O(g) And ΔH = -318.7kJ + 2×(-241.80kJ) =

-802.3kJ

Answer:

7 mol

Explanation:

Caffeine molecular formula C8H10N4O2. It has 2 atoms of oxygen.

                          C8H10N4O2         - 2O

                           1 mol                        2 mol

                           3.5 mol                    x mol

x = 3.5*2/1 = 7 mol

Answer: The molecules in the thermometer's liquid spread apart.

Explanation:

Mercury is the only metal that remains liquid at room temperature. It has a high coefficient of expansion therefore the its level rises when exposed to a temperature range. It can detect a slight change in temperature. It has a high  boiling point.

When the thermometer is placed in the water to measure the temperature, the molecules of thermometer liquid that is mercury only will spread due to high coefficient of expansion. This can be seen as rise in temperature.

Answer:

B

Explanation:

Just did the test

Answer:

D

Explanation:

Logitudinal waves also known as compression waves.

It involves displacing the medium perpendicular to the motion of the wave is not a characteristic of a transverse mechanical wave. Option B is correct.

A transverse mechanical wave is a disturbance created by it to transfer energy from one point to another. while the proposition happens the particle present within the medium get vibrates.

in a transverse wave, the particle present will vibrate up and down and are perpendicular to the wave's propagation direction. The particles shake in a directional wave in the longitudinal wave propagation.

Therefore, is not a characteristic of a transverse mechanical wave. Option B is correct. It involves displacing the medium perpendicular to the motion of the wave.

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Answer:

[Z] = 0.00248M

Explanation:

Based in the reaction:

2A(aq) + B(aq) ⇄ 2Z (aq)

K of the reaction is defined as:

K = [Z]² / [A]²[B] = 0.43

If you add, in the first, just 0.033M of  Z, concentrations in equilibrium are:

[Z] = 0.033M - 2X

[A] = 2X

[B] = X

Replacing in K equation:

0.43 = [0.033M - 2X]² / [2X]² [X]

0.43 = [0.033M - 2X]² / [2X]² [X]

0.43 = 4X² -0.132X + 0.001089 / 4X³

1.72X³ - 4X² + 0.132X - 0.001089 = 0

Solving for X:

X = 0.01526M

Replacing, concentration in equilibrium of Z is:

[Z] = 0.033M - 2*0.01526M = 0.00248M

Answer:

Less than 0.033 M

Explanation:

Hello,

In this case, given the equilibrium:

[tex]2A(aq) + B(aq) \rightleftharpoons 2Z (aq)[/tex]

Thus, the law of mass action is:

[tex]K=\frac{[Z]^2}{[A]^2[B]}[/tex]

Nevertheless, given the initial concentration of Z that is 0.033 M, we should invert the equilibrium since the reaction will move leftwards:

[tex]\frac{1}{K} =\frac{[A]^2[B]}{[Z]^2}=2.33[/tex]

Know, by introducing the change  due to the reaction extent, we can write:

[tex]2.33=\frac{(2x)^2*x}{(0.033M-2x)^2}[/tex]

Which has the following solution:

[tex]x_1=2.29M\\x_2=0.0181M\\x_3= 0.0153M[/tex]

But the correct solution is [tex]x=0.0153M[/tex]  since the other solutions make the equilibrium concentration of Z negative which is not possible. In such a way, its concentration at equilibrium is:

[tex][Z]_{eq}=0.033M-2*0.0153M=0.0024M[/tex]

Which is of course less than 0.033 M since the addition of a product shift the reaction leftwards in order to reestablish equilibrium (Le Chatelier's principle).

Regards.

Answer:

−153.1 J / (K mol)

Explanation:

Calculate the standard entropy of reaction at 298 K for the reaction Hg(liq) + Cl2(g) → HgCl2(s) The standard molar entropies of the species at that temperature are: Sºm (Hg,liq) = 76.02 J / (K mol) ; Sºm (Cl2,g) = 223.07 J / (K mol) ; Sºm (HgCl2,s) = 146.0 J / (K mol)

Hg(liq) + Cl2(g) → HgCl2(s)

Given that;

The standard molar entropies of the species at that temperature are:

Sºm (Hg,liq) = 76.02 J / (K mol) ;

Sºm (Cl2,g) = 223.07 J / (K mol) ;

Sºm (HgCl2,s) = 146.0 J / (K mol)

The standard molar entropies of reaction = Sºm[products] - Sºm [ reactants]

= 146.0 J / (K mol) – [76.02 J / (K mol) +223.07 J / (K mol) ]

= -153.09 J / (K mol)

= or -153.1 J / (K mol)

Hence the answer is  −153.1 J / (K mol)

Answer:

I. Lewis acid-base reaction

II. Arrhenius, Brønsted-Lowry, and Lewis' acid-base reaction

III. Brønsted-Lowry and Lewis'acid-base reaction

IV. Lewis acid-base reaction

Explanation:

According to Arrhenius, an acid is a substance that dissolves in water to produce H+ ions, and a base is a substance that dissolves in water to produce hydroxide (OH−) ions.

In the reaction below, AH is an avid, BOH is a base reacting together to form a salt(A-B+) and water only.

AH + BOH ---> A-B+ + H2O

According to Brønsted-Lowry definition, an acid is any substance that can donate a proton, and a base is any substance that can accept a proton.

In the reaction below, AH is an acid while B is a base, reacting together to form an acid-base conjugate pair.

AH + B <-----> BH+ + A-

According to Lewis' definition, an acid is a species that accepts an electron pair while a base donates an electron pair resulting in a coordinate covalently bonded compound, also known as an adduct. In the reaction below, A+ is an acid, B- is a base, reacting together to form product A-B.

A+ + B- ------> A-B

Considering the above definitions;

I. Cu²+ + 4 Cl− ---> CuCl4²− is a Lewis acid-base reaction because it involves electron sharing only.

II. Al(OH)3 + 3HNO3 ---> Al3+ + 3H2O + 3 NO3− is an Arrhenius, Brønsted-Lowry, and a Lewis acid-base reaction because it involves protons, electrons and hydroxide ions.

III. N2 + 3 H2 ---> 2NH3 is a Lewis acid-base reaction because it involves sharing of electrons only.

IV. CN− + H2O ---> HCN + OH is both a Lewis and Brønsted-Lowry acid-base reaction because both protons and electrons sharing is involved.

In a Bronsted-Lowry acid-base reaction reaction, an acid donates protons which is accepted by the base.

The following are useful definitions of acids and bases;

Based on these, we can now classify the reactions accordingly;

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Answer:

66.0 atm

Explanation:

We can calculate the osmotic pressure (π) using the following expression.

[tex]\pi = i \times M \times R \times T[/tex]

where,

Step 1: Calculate i

Sodium sulfate completely dissociates according to the following equation.

Na₂SO₄ ⇒ 2 Na⁺ + SO₄²⁻

Since it produces 3 ions, i = 3.

Step 2: Calculate M

We can calculate the molarity of Na₂SO₄ using the following expression.

[tex]M = \frac{mass\ of\ solute }{molar\ mass\ of\ solute\ \times liters\ of\ solution} = \frac{65.0g}{142.04g/mol \times 0.500L} =0.915M[/tex]

Step 3: Calculate T

We will use the following expression.

K = °C + 273.15

K = 20°C + 273.15 = 293 K

Step 4: Calculate π

[tex]\pi = 3 \times 0.915M \times \frac{0.08206atm.L}{mol.K} \times 293K =66.0 atm[/tex]

Answer:

- Four for iron, three for oxygen and 2 for iron (III) oxide:

[tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]

Explanation:

Hello,

In this case, the oxidation of iron is a widely acknowledged reaction occurring in ships and other machines exposed to the air or highly oxidizing medias. Thus, by the effect of oxygen, iron undergoes oxidation typically to iron (III) oxide:

[tex]Fe+O_2\rightarrow Fe_2O_3[/tex]

Nonetheless, the law of conservation of mass must be respected, therefore the coefficients balancing the reaction are four for iron, three for oxygen and 2 for iron (III) oxide:

[tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]

Best regards.

Answer: c. At equilibrium, the concentration of reactants is greater than the products

Explanation:

Equilibrium constant for a reaction is the ratio of concentration of products to the concentration of reactants each raised to the power its stoichiometric coefficients.

For the reaction:

[tex]NO_2(g)+NO_3(g)\rightleftharpoons N_2O_5(g)[/tex]

Equilibrium constant is given as:

[tex]K_{eq}=\frac{[N_2O_5]}{[NO_2]\times [NO_3]}[/tex]

[tex]2.1\times 10^{-20}=\frac{[N_2O_5]}{[NO_2]\times [NO_3]}[/tex]

When

a) K > 1, the concentration of products is greater than the concentration of reactants

b) K < 1, the concentration of reactants is greater than the concentration of products

c) K= 1, the reaction is at equilibrium, the concentration of reactants is equal to the concentration of products

Thus as [tex]K_{eq}[/tex] is [tex]2.1\times 10^{-20}[/tex] which is less than 1,

the concentration of reactants is greater than the concentration of products

Answer:

saturated

Explanation:

Answer:

85.34g of NH3

Explanation:

Step 1:

The balanced equation for the reaction. This is given below:

N2 + 3H2 —> 2NH3

Step 2:

Determination of the number of moles of NH3 produced by the reaction of 2.51 moles of N2. This is illustrated below:

From the balanced equation above,

1 mole of N2 reacted to produce 2 moles of NH3.

Therefore, 2.51 moles of N2 will react to produce = (2.51 x 2)/1 = 5.02 moles of NH3.

Therefore, 5.02 moles of NH3 is produced from the reaction.

Step 3:

Conversion of 5.02 moles of NH3 to grams. This is illustrated below:

Molar mass of NH3 = 14 + (3x1) = 17g/mol

Number of mole of NH3 = 5.02 moles

Mass of NH3 =..?

Mass = mole x molar Mass

Mass of NH3 = 5.02 x 17

Mass of NH3 = 85.34g

Therefore, 85.34g of NH3 is produced.

Answer:

M=0.816M

Explanation:

Hello,

In this case, we should consider the following reaction:

[tex]AgNO_3+KCl\rightarrow KNO_3+AgCl[/tex]

Thus, by knowing the 1:1 molar ratio of silver nitrate and potassium chloride, we can easily compute the moles of silver nitrate precipitating the 1570 mg of potassium chloride considering its molar mass of 74.5513 g/mol:

[tex]n_{AgNO_3}=1570mgKCl*\frac{1gKCl}{1000mgKCl} *\frac{1molKCl}{74.5513gKCl}*\frac{1molAgNO_3}{1molKCl} \\\\n_{AgNO_3}=0.021molAgNO_3[/tex]

Then, by using the volume of silver nitrate in liters (0.0258 L), we can directly compute the molarity:

[tex]M=\frac{0.021molAgNO_3}{0.0258L}\\ \\M=0.816M[/tex]

Regards.

Answer:

0.067M Fe(NO3)3

Explanation:

A stock solution is a concentrated solution that is diluted to prepare the solutions that you will use.

The volume of the stock solution is 3.0mL + 10.0mL + 17.0mL= 30.0mL.

The ratio between volume of the aliquot (10.0mL) and total volume (30.0mL) is called dilution factor, that is: 30.0mL / 10.0mL = 3

That means the Fe(NO3)3 is diluted 3 times. That means the molar concentration of the stock solution is:

0.200M / 3 =

Answer:

0.287 mole of PCl5.

Explanation:

We'll begin by calculating the number of mole in 51g of Cl2. This is illustrated below:

Molar mass of Cl2 = 2 x 35.5 = 71g/mol

Mass of Cl2 = 51g

Number of mole of Cl2 =..?

Mole = Mass /Molar Mass

Number of mole of Cl2 = 51/71 = 0.718 mole

Next, we shall write the balanced equation for the reaction. This is given below:

P4 + 10Cl2 → 4PCl5

Finally, we determine the number of mole of PCl5 produced from the reaction as follow:

From the balanced equation above,

10 moles of Cl2 reacted to produce 4 moles of PCl5.

Therefore, 0.718 mole of Cl2 will react to produce = (0.718 x 4)/10 = 0.287 mole of PCl5.

Therefore, 0.287 mole of PCl5 is produced from the reaction.

Answer:

balanced because the total number of oxygen atoms is 3.

Answer:

The molecules in the thermometer’s liquid spread apart

Explanation:

The molecules in the thermometer’s liquid spread apart.

A thermometer is a device that measures temperature or a temperature gradient.

The liquid (water) in thermometer exhibits convex meniscus, as a result of this meniscus, the water molecules in the thermometer will spread apart when temperature is measured.

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Answer:

a) ammonium ion

b) amide ion

Explanation:

The order of decreasing bond angles of the three nitrogen species; ammonium ion, ammonia and amide ion is NH4+ >NH3> NH2-. Next we need to rationalize this order of decreasing bond angles from the valence shell electron pair repulsion (VSEPR) theory perspective.

First we must realize that all three nitrogen species contain a central sp3 hybridized carbon atom. This means that a tetrahedral geometry is ideally expected. Recall that the presence of lone pairs distorts molecular structures from the expected geometry based on VSEPR theory.

The amide ion contains two lone pairs of electrons. Remember that the presence of lone pairs causes greater repulsion than bond pairs on the outermost shell of the central atom. Hence, the amide ion has the least H-N-H bond angle of about 105°.

The ammonia molecule contains one lone pair, the repulsion caused by one lone pair is definitely bless than that caused by two lone pairs of electrons hence the bond angle of the H-N-H bond in ammonia is 107°.

The ammonium ion contains four bond pairs and no lone pair of electrons on the outermost nitrogen atom. Hence we expect a perfect tetrahedron with bond angle of 109°.

Answer:

D

Explanation:

gr. 2.3 at 25°C; valence +3. Boron is a nonmetallic element existing as a dark brown to black amorphous powder or as an extremely hard, usually jet-black to silver-gray, brittle, lustrous, metallike crystalline solid

it is a network solid, a lattice of many covalent bonds (like diamond, except that it is black rather than transparent).

Network solid kind of solid is crystalline boron (B). Hence, option D is correct.

A network solid is a solid where all the atoms are covalently bonded in a continuous network.

Boron is a nonmetallic element existing as a dark brown to black amorphous powder or as an extremely hard, usually jet-black to silver-grey, brittle, lustrous, metallike crystalline solid

It is a network solid, a lattice of many covalent bonds (like a diamond, except that it is black rather than transparent).

Hence, option D is correct.

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