PLEASE ANSWER QUICKLY I'M IN A TEST
Which important property of DNA did Friedrich Miescher discover? A. It is made partly of sugar molecules. B. It has a double-helix structure. C. It is three-dimensional. D. It is found in the nucleus of a cell.

Answers

Answer 1

Answer:

D. It is found in the nucleus of a cell.

Explanation:

Friedrich Miescher first discovered DNA as a biomolecule. He isolated nuclein in which DNA is wrapped around cellular proteins such as Histones. Many years after Miescher's discovery it was proved that DNA is the hereditary material in cells. In the times of Miescher proteins were believed to be the molecules of hereditary.

Answer 2

The important property of DNA that Friedrich Miescher discovered is that it is made partly of sugar molecules. Option A.

Contribution of Friedrich Miescher

Friedrich Miescher discovered an essential property of DNA, revealing that it contains sugar molecules. In the late 1800s, he isolated a substance from cell nuclei that contained both phosphorus and nitrogen.

Later recognized as DNA, this discovery laid the foundation for understanding the molecular composition of genetic material.

While options B, C, and D are also relevant aspects of DNA's structure and location, it was Miescher's identification of DNA's sugar component that marked a pivotal step in unraveling the molecule's role in inheritance and genetics.

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Related Questions

What air moves horizontally or parallel to the ground?

Answers

Wind, air that moves to the ground

Please fill out all of table!!

Answers

1) Alkali metals - s block; one valence electron; lose one valence electron; charge of an ion +1.

Alkali metals have electronegativity from 0.7 to 1, lowest in Periodic table of elements, which means that alkali metals (I group in Periodic table) has positive oxidation number in compounds.

Electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

For example, sodium (Na) is an element with atomic number 11 and it has one valence electron (3s¹) like all alkaline metals.

Electron configuration of sodium atom: ₁₁Na 1s² 2s² 2p⁶ 3s¹.

2) Alkaline earth metals - s block; two valence electrons; lose two electrons; charge of an ion is +2.

Beryllium, magnesium,calcium and strontium are alkaline earth metals. The elements have very similar properties. Alkaline earth metals have in common an outer s- electron shell (two electrons).

For example, atomic number of calcium is 20, it means that it has 20 protons and 20 electrons, so atom of calcium is neutral.

Electron configuration of calcium atom: ₂₀Ca 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²; calcium has two valence electrons (4s²).

3) Boron group - p block; three valence electrons; lose three electrons; charge of metal ions is +3; no nonmetals in this group; none.

For example, boron is an element with atomic number 5, which means it has 5 protons and 5 electrons, bcause atom has neutral charge.

Electron configuration of boron: ₅B: 1s² 2s² 2p¹, it has three valence electrons in 2s and 2p orbitals.

Atomic number is the number of protons, which is characteristic of a chemical element.

4) Carbon group - p block; four valence electrons; lose two or four electrons; charge of metal ions is +2 or +4; nonmetals gain four electrons; charge of nonmetals is -4.

Carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb) and flerovium (Fl) are in group 14 of Periodic table. They have same number of valence electrons (four) and similar chemical properties.

For example, carbon is a chemical element with symbol C and atomic number 6, which means it has 6 protons and six electrons. Valence electrons are in 2s and 2p orbitals.

Electron configuration of carbon atom: ₆C 1s² 2s² 2p².

5) Nitrogen group - p block;  five valence electrons; lose three or five electrons; charge of metal ions is +3 or +5; nonmetals gain three electrons; charge of nonmetals is -3.

Nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi) and moscovium (Mc) are in group 15 of Periodic table. They have same number of valence electrons (five).

For example, bizmuth (Bi) has atomic number 83, it has 83 protons and 83 electrons. Valence electrons are in 6s and 6p orbitals.

Electron configuration of bizmuth atom: ₈₃Bi [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p³.

6) Oxygen group - p block;  six valence electrons; lose four or six electrons; charge of metal ions is +4 or +6; nonmetals gain two electrons; charge of nonmetals is -2.

Oxygen (O), sulfur (S), selenium (Se), tellurium (Te) and the radioactive element polonium (Po) are in group 16 of Periodic table. They have same number of valence electrons (six).

For example, electron configuration of oxygen atom: ₈O 1s² 2s² 2p⁴.  

Oxygen atom has six valence electrons (2s² 2p⁴), so it is in 16 group of Periodic table of elements.  

7) Halogens - p block; seven valence electrons; nonmetals gain one electron; charge of nonmetals is -1.

Halogen elements are in group 17: fluorine (F), chlorine (Cl), bromine (Br) and iodine (I). They are very reactive and easily form many compounds.

Halogens need to gain one electron to have electron cofiguration like next to it noble gas.

For example, fluorine has 9 electrons and it gain easily one electron in chemical reaction to have electron configuration like noble gas neon (Ne) with 10 electrons.

Electron configuration of fluorine: ₉F 1s² 2s² 2p⁵.

8) Noble gases - p block; eight valence electrons (except helium with two valence electrons); do not gain or lose electrons; none.

Noble gases (group 18) are in group 18: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). They have very low chemical reactivity.  

Noble gases have very stable electron configuration and does not need to gain electrons, only when they gain energy .

Helium has atomic number 2, it has 2 protons and 2 electrons.

Electron configuration of helium atom: ₂He 1s².

Electron configuration of krypton atom:  

₃₆Kr 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶.

Give the electron configuration for the chloride ion. (please show the process!) =)

Answers

Answer:- [tex]1s^22s^22p^63s^23p^6[/tex]

Explanations:- Atomic number of chlrone(Cl) is 17 it means it has 17 electrons. It's electron configuration is: [tex]1s^22s^22p^63s^23p^5[/tex] .

Chloride ion is formed when Cl accepts one electron:

[tex]Cl+e^-\rightarrow Cl^-[/tex]

So, electrons for the chloride ion = 17+1 = 18

If we look at the electron configuration of Cl then 3p is still vacant as there are 5 electrons in it and it could have maximum 6 electrons. So, this 18th electron goes to 3p and the electron configuration of chloride ion becomes:

[tex]1s^22s^22p^63s^23p^6[/tex] .


The requirements of atoms to be able to participate in hydrogen bonding with a hydrogen atom include all of the following except A. atoms must not be able to closely approach the hydrogen. B. atoms must be electronegative. C. atoms must have one lone pair of electrons. D. atoms must be small.

Answers

B. atoms must be electro negative.


Answer:

The answer is A.

Explanation:

This is a specific type of polar interaction that is established between two atoms with high electronegativity, usually between O or N, and an atom of H. In the case of oxygen, with a total of 8 electrons, two pairs of solitary electrons are presented and can act as acceptors of two hydrogen bridges. Nitrogen has one less electron and therefore has only one pair of solitary electrons to form a hydrogen bridge. These orbitals have a high negative charge density, and can, therefore, bind to the positive charge of hydrogen.

The interatomic distance between the hydrogen and the acceptor is less than the sum of its Van der Waals radius. The atomic radius of N and O are relatively small.

Have a nice day!

What is the Lewis structure for H2Se

Answers

Basically since there’s 2 hydrogen’s there will be two H’s on either side of your other element. And Se is in group 6 which means it has 6 valence electrons. When you combine 6 and 2 from the hydrogen you get 8. You then should place 8 dots around Se two on each side.

So something like H Se(with 8 dogs around it) H

Early models of our solar system were usually based on experimentation

the best science of the time

the discoveries

of the best scientists

philosophy and religion

Answers

Based on the question and the given data, philosophy and religion.

in the process of electricity, what flows through the wires?A) protons B)neutronsC)electronsD)positrons

Answers

Electrons is your answer

Answer: C.

electrons

Explanation: edmentum

When hydrochloric acid reacts with potassium hydroxide solution, the following reaction occurs. HCl (aq) + KOH (aq) H2O (l) + KCl (aq) The reaction gives off heat energy, so it is an reaction.

Answers

A reaction that gives off heat energy is called Exothermic. (Answer).

A reaction that absorbs heat from the surroundings is called endothermic.

Answer: Exothermic

Explanation:

Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and [tex]\Delta H[/tex] for the reaction comes out to be negative.

Endothermic reactions are defined as the reactions in which energy of the product is greater than the energy of the reactants. The total energy is absorbed in the form of heat and [tex]\Delta H[/tex] for the reaction comes out to be positive.

[tex]HCl(aq)+NaOH(aq)\rightarrow KCl(aq)+H_2O(aq)[/tex] is an example of neutralization as acid and base combines to form salt and water and exothermic reaction as it releases heat in the reaction.

an air sample consists of 99.6% of nitrogen-14 and 0.4% of nitrogen-15. what is the average mass of nitrogen in this sample?

Answers

 The  average mass  of nitrogen   is  14

 

         calculation

 step 1 :  multiply each percentage  by mass  number

 14 x 99.6  =1394

15 x 0.4 =   6


Step 2: add them up

 1394 + 6  = 1400

step 3: Then  divide by 100

= 1400/100 = 14

Answer:The average atomic mass of nitrogen is 14.004

Explanation:

Abundance of nitrogen-14 = 99.6 %

Fractional abundance[tex]=\frac{99.6}{100}=0.996[/tex]

Abundance of nitrogen-15 = 0.4 %

Fractional abundance[tex]=\frac{0.4}{100}=0.004[/tex]

Average atomic mass of an element =

[tex]\sum(\text{atomic mass of an isotopes}\times (\text{fractional abundance}))[/tex]

Average atomic mass of nitrogen =

[tex]14\times 0.996+15\times 0.004amu=14.004[/tex]

The approximate atomic mass of nitrogen is 14.004

Abdid is an astronomer who has been observing objects that orbit the sun in the Astro belt . He finds a previously undiscovered round rocky object that is not similar in shape to the rest of the asteroids what has abdid most likely found

Answers

Since it is round, and in the asteroid belt, he has most likely found a Dwarf planet. This is because it is round, so it might be round because of it's gravity.

Answer:

A. a new dwarf planet

Explanation:

Structural formulas are like models because they show _[blank]_.

Which answer best completes this statement?

a condensed way of writing a compound
how elements arrange within a compound
how electrons arrange within a compound
the three-dimensional shape of a compound

Answers


The correct option is:

how elements arrange within a compound  


Structural formula are like models because they show how elements arrange within a compound.  

how would you measure density of a rock

Answers

Use the D = M/V equation, in which Density can be found by dividing Mass/Volume.

To solve, first find a rectangular prism tub that is filled to a certain level. Next, place the rock inside to find the amount of displacement (or how high the water level goes up.) In this way, you can find the volume of the rock.

Next, solve for the Mass. This can be found by dividing the total weight from the gravitational pull. This would give you the mass.

Finally, to find Density, divide the Mass found with the Volume. This would give you your final answer

~

The term “ average atomic mass “ is a ______average so is calculator different Lee from a normal average

Answers

Average atomic mass of an element is a sum of the product of the isotope mass and its relative abundance.

For example: Chlorine has 2 isotopes with the following abundances

Cl(35): Atomic mass = 34.9688 amu; Abundance = 75.78%

Cl(37): Atomic mass = 36.9659 amu; Abundance = 24.22 %

Average atomic mass of Cl = 34.9688(0.7578) + 36.9659(0.2422) =

                                             = 26.4993 + 8.9531 = 35.4524 amu

Thus, the term “ average atomic mass “ is a weighted average so it is calculated differently from a normal average

A child is male because he has one X chromosome and one Y chromosome where did these chromosomes come from

Answers

it would come from your mom and dad

Answer the following for the reaction: 3AgNO3(aq)+Na3PO4(aq)→Ag3PO4(s)+3NaNO3(aq)

1. How many milliliters of a 0.255 MAgNO3 solution are required to react with 31.1 mL of 0.135 MNa3PO4 solution?
2. How many grams of silver phosphate are produced from the reaction of 23.0 mL of a 0.195 MAgNO3 solution and excess Na3PO4?

Answers

Answer:1) Volume of [tex]AgNO_3[/tex] required is 55.98 mL.

2) 0.62577 grams of [tex]Ag_3PO_4[/tex] is produced.

Explanation:

[tex]3AgNO_3(aq)+Na_3PO_4(aq)\rightarrow Ag_3PO_4(s)+3NaNO_3(aq)[/tex]

1) Molarity of [tex]AgNO_3,M_1=0.225 M[/tex]

Volume of [tex]AgNO_3.V_1=?[/tex]

Molarity of [tex]Na_3PO_4,M_2=0.135 M[/tex]

Volume of [tex]Na_3PO_4,V_2=31.1 mL=0.0311 L[/tex]

[tex]Molarity=\frac{\text{number of moles}}{\text{volume of solution in liters}}[/tex]

[tex]\text{number of moles }Na_3PO_4=M_2\times V_2=0.135 mol/L\times 0.0311 L=0.0041985 moles[/tex]

According to reaction, 1 mole of [tex]Na_3PO_4[/tex] reacts with 3 mole of [tex]AgNO_3[/tex], then, 0.0041985 moles of [tex]Na_3PO_4[/tex] will react with:

[tex]\frac{3}{1}\times 0.0041985[/tex] moles of [tex]AgNO_3[/tex] that is 0.0125955 moles.

[tex]M_1=0.225 M=\frac{\text{number of moles of }AgNO_3}{V_1}[/tex]

[tex]V_1=\frac{0.0125955 moles}{0.225 M}=0.05598 L=55.98 mL[/tex]

Volume of [tex]AgNO_3[/tex] required is 55.98 mL.

2)

[tex]Molarity=0.195 M=\frac{\text{number of moles}}{\text{volume of solution in liters}}[/tex]

Number of moles of [tex]AgNO_3=0.195\times 0.023 L=0.004485 moles[/tex]

According to reaction, 3 moles of [tex]AgNO_3[/tex] gives 1 mole of [tex]Ag_3PO_4[/tex], then 0.004485 moles of [tex]AgNO_3[/tex] will give:[tex]\frac{1}{3}\times 0.004485[/tex] moles of [tex]Ag_3PO_4[/tex] that is 0.001495 moles.

Mass of [tex]Ag_3PO_4[/tex] =

Moles of [tex]Ag_3PO_4[/tex] × Molar Mass of [tex]Ag_3PO_4[/tex]

= 0.001495 moles × 418.58 g/mol = 0.62577 g

0.62577 grams of [tex]Ag_3PO_4[/tex] is produced.

1) What is the mole ratio of D to A in the generic chemical reaction? (2 points) Page 390 helps with understanding mole ratios. Be sure you’re only looking at the ratio of D to A. You can ignore B & C. 2A+ B  C + 3D

Answers

Answer:- The mole ratio of D to A is 3:2.

Explanations:- Mole ratio for a chemical equation is the ratio of the coefficients of the molecules. Coefficients are the numbers used to balance the chemical equations.

For the given generic chemical equation, the coefficient of molecule A is 2 and the coefficient of D is 3. It means 2 molecules of A react with 3 molecules of D. So, the mole ratio of A to D is 2:3.

Since, we are asked about the mole ratio of D to A so we will write the coefficient of D first and hence the mole ratio of D to A is 3:2.

Iron(III) oxide is formed when iron combines with oxygen in the air. How many grams of Fe2O3 are formed when 33.4 g of Fe reacts completely with oxygen?
Molar Mass information: Iron = 55.8 g/mol, Oxygen= 15.9 g/mol

Answers

    The grams of  Fe₂O₃   that are formed is  47.68 g

calculation

Step 1: write   the equation for reaction

4 Fe +3O₂ → 2 Fe₂O₃

Step 2: find  the  moles  of Fe

moles = mass÷  molar mass

 = 33.4 g÷55.8 g/mol =0.5986 moles

Step 3 : use the mole ratio to determine the moles of Fe₂O₃

That is  from  equation above Fe:Fe₂O₃  is 4:2 therefore the moles of Fe₂O₃ is  =  0.5986 moles x 2/4 =0.2993 moles

Step 4 : find the mass  of Fe₂O₃

mass = mass x molar mass

The molar mass of Fe₂O₃  = (55.8 x 2 +(15.9 x3) = 159.3 g/mol

mass is therefore =  0.2993 moles x 159.3 g/mol =47.68 g

Answer:

47.8 g

Explanation:

Discuss the shapes of s- orbitals, p-orbitals and d-orbitals.

Answers

The azimuthal quantum number (l) determines its orbital angular momentum and describes the shape of the orbital.

s-orbitals (for example 1s, 2s) are spherically symmetric around the nucleus of the atom.

p-orbitals are dumb-bell shaped. l = 0,1...n-1, when l = 1, that is p subshell.

d-orbitals are butterfly shaped.

A _____ is a mountain created from eruptions of lava, ash, rocks, and hot gases.

Answers

Valcano i your answer i believe

What does graphite contain that is similar to metals

Answers


It is often confusing why graphite seems to have some metallic properties (conductivity and shiny surface) and some non-metallic properties (brittle). The reason for this is that graphite is composed of carbon which is a non metal and pure carbon in diamonds is an insulator like most non metals. A better way to state the question is “why does graphite a non metal have any metallic properties?”. So the reason is that graphite uses a different conduction mechanism then metals. Metals conduct electricity and heat by the motion of their loosely bound outer electrons. Non metal conduction like that found in graphite and some semiconductors like zinc oxide is caused by electron hoping. The electron hoping mechanism also allows for increased thermal conductivity. This happens in graphite due to the hexagonal planar crystal structure. Graphite is still a non metal but it has a few properties related to it’s electron structure that make it metal like but only in those specific ways. Otherwise graphite is still a non metal so it is brittle and crumbles when you try to shape it.


How do nonmetals conduct electricity? well . by giving up electrons . poorly . better than metals.

Answers

Usually poorly, especially at room temperature for most of them. The gases do not conduct. Some that are marginally non metals (silicon germanium and graphite) conduct passably well but do not conduct as well as copper or silver.

Non metals do not have easily freed electrons and that is why they do not conduct electricity.

Which of the following types of electromagnetic waves has a frequency greater than ultraviolet waves?

A) X rays
B) infrared waves
C) microwaves
D)visible light

Answers

Answer:

A) X-rays

Step-by-step explanation:

Ultraviolet rays have a frequency range of 10¹⁵ Hz to 10¹⁷ Hz.

X-rays have a frequency range of 10¹⁷ Hz to 10²⁰ Hz, so they have a higher frequency than UV waves.

B) is wrong. The frequency range of infrared light is 10¹³ Hz to 4 × 10¹⁴ Hz.

C) is wrong. The frequency range of microwaves is 3 ×10¹¹ Hz to 10¹³ Hz.

D) is wrong. The frequency range of microwaves is 4 ×10¹⁴ Hz to 7.5 × 10¹⁴ Hz.

The X-rays has a frequency greater than ultraviolet waves.  

• The range of all the kinds of electromagnetic radiation is known as the electromagnetic spectrum.  

• The types of the electromagnetic waves, which makes up the electromagnetic spectrum are the visible light, microwaves, infrared light, UV rays, X-rays, and gamma rays.  

• The energy of the waves is directly proportional to its frequency and inversely proportional to their wavelengths.  

• The radiowaves exhibits the photons with least energies, followed by microwaves, infrared rays, visible, UV rays, X-rays, and the most energetic of all the waves is the gamma rays.  

• The wavelengths of the UV rays is smaller than infrared waves, microwaves, and visible light, however, it is greater than X-rays and gamma rays.  

• Thus, the frequencies of UV rays is more than the infrared waves, microwaves, and visible light, but is lesser than the frequencies of X-rays and gamma rays.  

Thus, of the mentioned options, X-rays will possess greater frequency than UV rays.  

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HURRY 10 POINTS!!!
Earth’s magnetic field is formed mostly by:
A. Molten iron alloy
B. solar wind
C. solar plasma

Answers

Earths magnetic field is formed mostly by

B. SOLAR WIND

Two 20.0-g ice cubes at –15.0 °C are placed into 265 g of water at 25.0 °C. Assuming no energy is transferred to or from the surroundings, calculate the final temperature, Tf, of the water after all the ice melts. heat capacity of h20(s) is 37.7j/kmol. heat capacity of h20(l) is 75.3j/kmol. enthalpy of fusion of h20 is 6.01j/kmol.

Answers

Answer:

10.3 °C

Step-by-step explanation:

This is an isolated system so

heat gained by ice + heat lost by water = 0

Heat to warm ice + heat to melt ice + heat to warm melt + heat lost by water = 0

     q₁     +     q₂        +      q₃      +     q₄      = 0

n₁C₁ΔT₁ + n₁ΔH_fus + n₁C₃ΔT₃ + n₄C₃ΔT₄  = 0

Step 1: Calculate q₁

n₁ = 40.0 g × 1/18.02

n₁ = 2.220 mol

C₁ = 37.7 J·K⁻¹mol⁻¹

ΔT₁ = T_f – T_i  

ΔT₁ = 0.0 – (-15)

ΔT₁ = 15 °C = 15 K

q₁ = 2.220 × 37.7 × 15  

q₁ = 1255 J

q₁ = 1.255 kJ

===============

Step 2. Calculate q₂

ΔH_fus = 6.01 kJ·mol⁻¹

q₂ = 2.220 × 6.01

q₂ = 13.34 kJ

===============

Step 3: Calculate q₃

C₃ = 75.3 J·K⁻¹mol⁻¹

ΔT₃ = T_f – T_i  = x – 0 °C  

ΔT₃ = x °C = x K

q₃ = 2.220 × 75.3 × x

q₃ = 167x J

q₃ = 0.167x kJ

===============

Step 4. Calculate q₄

n₄ = 265 × 1/18.02

n₄ = 14.71 mol

ΔT₄ = T_f – T_i  = x – 25.0 °C  

q₄ = 14.71 × 75.3 × (x – 25.0)

q₄ = 1107 × (x – 25.0)

q₄ = 1107x  – 27 680 J

q₄ = 1.107x – 27.68 kJ

===============

Step 5. Solve for x

1.255 + 13.34 + 0.167x + 1.107x - 27.68 = 0

1.274x - 13.08 = 0

1.274x = 13.08

x = 13.08/1.274

x = 10.3 °C

The final temperature is -10.3 °C.

what is a chemical change?

Answers

Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions

Chemical change accurs when a substance changes form like liquid to solid.

Which two factors does the power if a machine depend on
A. work and distance
B. force and distance
C. work and time
D. time and distance

Answers

The definition of mechanical power is


                       Power = (work done) / (time to do the work).


From that definition, it looks pretty much like the power of a machine

depends on work and time.


Answer:

c. work and time

Explanation:

c is right on plato

which of the following elements has the highest first ionization energy? strontium calcium magnesium or beryllium

Answers

Beryllium.

Explanation

All four elements are found in the second column to the left of a periodic table. They are group 2 elements.

The 1st ionization energy generally decrease down each group.

Elements in each group have the same number of electrons in the outermost occupied electron shell. Electrons in the inner shell shield those in the outer shell from attractions from the nucleus, known as the shielding effect. The number of protons in each atom increase by more than 8 in each period. However, due to this effect, electrons in the outermost shell experience a far weaker force pulling them towards the center of the atom. For atoms of the four group 2 elements, electrons in the outermost layer would behave as if there's only two protons inside their nucleus. As a result, their end up with rather similar ionization energies.

Despite the same effective charge on each electron, the mean radius of the electrons increase down the group. Beryllium is in the second period; its electrons occupy only two electron shells in the ground state. On the contrary, strontium is in the fifth period; its electrons occupy up to five electrons shells in its ground state. The strength of electrostatic attraction decreases as the two charges move apart. As a result, outermost electrons in beryllium are way more attached to the nucleus than those in strontium.

FYI, the 1st ionization energy of the four elements are shown below:

Be: 899.50 kJ/molMg: 737.750 kJ/molCa: 589.830 kJ/molSr: 549.470 kJ/mol

The element with the highest first ionization energy among the choices is; Beryllium, Be

The ionization energy of an element is the energy required to remove one of the electrons in its outermost shell.

The first ionization energy of elements is inversely proportional to the atomic radii of elements.

This is so because a lesser atomic radius corresponds to greater electrostatic attraction between the electron and the nucleus of the atom.

We must also state that the atomic radius of elements in the periodic table increases down a group and decreases across a period.

In essence, the smaller the atom of an element, the larger is its first ionization energy.

Strontium --Period 6, group 1

Calcium --Period 4, group 2

Magnesium --Period 3, group 2

Beryllium -- period 2, group 2

The element with the highest first ionization energy is the smallest element and is therefore Beryllium, Be.

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What is the volume of 7.25 g of oxygen gas at STP?

Answers

Answer:

5.15 L

Step-by-step explanation:

This looks like a case where we can use the Ideal Gas Law to calculate the volume.

pV = nRT       Divide both sides by p

 V = (nRT)/p

Data:

m = 7.25 g

R = 0.083 14 L·atm·K⁻¹mol⁻¹

T = (0 +273.15) K = 273.15K

p = 1 bar (Note: STP is 1 bar and 0°C)

Calculations:

(a) Moles of O₂

n = m/M

n = 7.25/32.00

n = 0.2266 mol

(b) Volume

V = (0.2266 × 0.083 14 × 273.15)/1

V = 161.3/2.00

V = 5.15 L  

The volume of 7.25 g oxygen gas at STP has been 5.075 L.

The oxygen has been assumed to be an ideal gas. The volume of 1 mole of an ideal gas at STP has been 22.4 L.

Volume of Oxygen at STP

The moles of a gas has been given as:

[tex]\rm Moles=\dfrac{Mass}{Molar\;mass}[/tex]

The given mass of oxygen has been 7.25 g.

The molar mass of oxygen has been 32 g.

The moles of oxygen gas have been given as:

[tex]\rm Moles\;O_2=\dfrac{7.25}{32}\\Moles\;O_2= 0.226\;mol[/tex]

The moles of oxygen available has been 0.226 mol.

The volume of 0.226 mole oxygen at STP has been:

[tex]\rm 1\;mol=22.4\;L\\0.226\;mol=0.226\;\times\;22.4\;L\\0.226\;mol=5.075\;L[/tex]

The volume of 7.25 g oxygen gas at STP has been 5.075 L.

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Is Fe2O3+H2--2Fe+3H2O balanced or unbalanced?

Answers

hydrogen is not balanced

the right balanced equation is

Fe2O3 + 3 H2 -> 2Fe + 3H2O

what is happening with the valence electrons of two atoms in a covalent bond?

Answers

A pair of oxygen atoms can form an O2 molecule in which each atom has a total of eight valence electrons by sharing two pairs of electrons. The term covalent bond is used to describe the bonds in compounds that result from the sharing of one or more pairs of electrons.


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