In the periodic table, atomic radius decreases as we move left to right across a period. In period 3, this results in the elements Si, Mg, Na, and Al being ranked in decreasing atomic radius as follows: Na, Mg, Al, and Si.
Explanation:The atomic radius of an element is generally defined as the total distance from the center of an atom's nucleus to its outermost shell of electrons. In the periodic table, the atomic radius tends to decrease as we move across a period from left to right, and it increases as we move down a group.
Considering the elements Si, Mg, Na, and Al, all these elements are located in the same period in the periodic table, period 3. Therefore, as we move across this period from left to right, the atomic radius should decrease.
And following this rule, the elements should rank in this order from largest to smallest atomic radius: Na > Mg > Al > Si.
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The elements Si, Mg, Na, Al in order from largest to smallest atomic radius would be Na, Mg, Al, Si. This is based on the general trend in the periodic table where atomic radius decreases as you move from left to right across a period and increases as you move down a group.
Explanation:In the periodic table, atomic radius generally decreases as you move from left to right across a period and increases as you move down a group. So, considering this, Si, Mg, Na, Al are positioned in the periodic table as follows: Na (period 3, group 1), Mg (period 3, group 2), Al (period 3, group 13), and Si (period 3, group 14). Following the trend in the periodic table, the order from largest to smallest atomic radius would be Na, Mg, Al, Si.
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How do you do this question?
Answer:
[tex]\boxed{\text{(D) 2 HCHO}_{2}}[/tex]
Explanation:
HCOOH + H₂O ⇌ H₃O⁺ + HCOO⁻
HCHO₂ is a weak acid. It dissociates only to a few percent, so there will be more HCHO₂ than H₃O⁺ present.
After H₂O, the most abundant species will be undissociated HCHO₂, so the answer will be either (B) or (D).
We can use an ICE table to organize the calculation of the pH.
HCOOH +H₂O ⇌ H₃O⁺ + HCOO⁻
I/mol·L⁻¹: 0.5 0 0
C/mol·L⁻¹: -x +x +x
E/mol·L⁻¹: 0.5 - x x x
[tex]K_{\text{a}} = \dfrac{\text{[H}_{3}\text{O}^{+}]\text{HCOO}^{-}]} {\text{[HCOOH]}} = 2 \times 10^{-4}\\\\\dfrac{x^{2}}{0.5-x} = 2 \times 10^{-4}[/tex]
Check for negligibility of x
[tex]\dfrac{ 0.5 }{2 \times 10^{-4}} = 2500 > 400.[/tex]
∴ x ≪ 0.5
[tex]\dfrac{x^{2}}{0.5} = 2 \times 10^{-4}[/tex]
x² = 0.5 × 2 × 10⁴ = 1 × 10⁻⁴
x = √(1 × 10⁻⁴) = 1 × 10⁻²
[H₃O⁺] = x mol·L⁻¹ = 1 × 10⁻² mol·L⁻¹
pH = -log[H₃O⁺] = -log(1 × 10⁻²) = 2
The correct answer is [tex]\boxed{\textbf{(D) 2 HCHO}_{2}}[/tex].
Which of the following is true regarding the inner transition elements? (PF)
A. These include the lanthanides and actinides and do not have f sublevels.
B. They occupy the d block of the periodic table.
C. These include all elements in groups 3-12.
D. Their valence electrons can be located in both s and f sublevels.
Answer:The answer is D
Explanation:
The inner transition elements are those in the two long rows at the bottom of the Periodic Table.
The lanthanide series starts after Ba in Period 6, and the actinide series starts after Ra in Period 7.
Thus, we would predict their electron configurations to be of the form
However, the energy levels of the ns, (n-1)d, and (n-2)f orbitals are so close in energy that there are many exceptions to our predictions
For example, here are some electron configurations.
La = [Xe]6s²5d (not [Xe]6s²4f)
Ce = [Xe]6s²4f5d (not [Xe]6s²4f²)
Pr = [Xe]6s²4f³ (as predicted)
Thus, their valence electrons can be in both s and f (and sometimes d) sublevels.
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The answer should be d
Why are emission spectra referred to as the fingerprints of the elements?
They are referred to as the finger prints of the element because they show the particular properties of the elements which differentiates one element from other elements
The emission spectrum or emission spectra is characteristic for each element as it provides information which is unique to each element.
What is emission spectrum?
Emission spectrum is defined as a spectrum of a chemical compound or substance composed of frequencies of electromagnetic radiation. Radiations which are emitted while electron make transition from higher to lower energy level.
Energy of photon is equal to the difference between the two energy states . There are many possible electronic transitions in an atom and every transition has a specific wavelength.
Collection of different transitions with respect to different wavelengths makes up an emission spectrum.Emission spectrum of each element is unique and therefore spectroscopy is used to identify elements which are present in different substances.
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It is generally seen that, when a substance absorbs heat energy, its heating curve shows two plateaus. which phenomenon is indicated by these plateaus? select one:
a. melting
b. boiling
c. phase change
d. crystallization
The answer is a. Melting
What is the expected change in the freezing point of water for a 0.015 m aqueous solution of alcl3?
Answer:
- 0.028 °C
Explanation:
The depression in freezing point of water (ΔTf) due to adding a solute to it is given by: ΔTf = Kf.m.Where, ΔTf is the depression in water freezing point (ΔTf = ???°C).
Kf is the molal freezing point depression constant of the solvent (Kf = 1.86 °C/m).
m is the molality of AlCl₃ (m = 0.015 m).
∴ ΔTf = Kf.m = (1.86 °C/m)(0.015 m) = 0.0279 °C ≅ 0.028 °C.
∵ ΔTf = freezing point of pure water - freezing point of the solution in presence of AlCl₃.
∴ freezing point of the solution in presence of AlCl₃ = freezing point of pure water - ΔTf = 0.0 °C - 0.028 °C = - 0.028 °C.
For the baeyer–villiger oxidation of cyclohexyl methyl ketone
just be postice and you will find the answer
If 200 mL of water is evaporated from 400 mL of 0.5 M aqueous salt solution, what is the resulting concentration? 1. 2.5 × 10−1 M 2. 2.5 × 101 M 3. 2.5 × 100 M 4. 2.5 × 10−2 M 5. None of these
Answer:
None of these
Explanation:
Using the dilution formula;
M1V1 = M2V2
where M1 is the initial concentration, V1 is the initial volume, M2 is the concentration attained while V2 is the new volume.
Therefore;
M2 = M1V1/V2
= (400 mL × 0.5) / 200 mL
= 1 M
Therefore, the resulting concentration is 1M
Thus, the correct answer is "none of these"
If 200 mL of water is evaporated from 400 mL of 0.5 M aqueous salt solution, the resulting concentration is 1.0 M.
What is evaporation?Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase.
A 400 mL solution has a concentration of 0.5 M. After 200 mL of water evaporate, 200 mL of solution remain. We can calculate the final concentration using the following expression.
C1 . V1 = C2 . V2
C2 = C1 . V1 / V2
C2 = 0.5 M . 400 mL / 200 mL = 1.0 M
where,
C1 and V1 are the initial concentration and volume.C2 and V2 are the final concentration and volume.If 200 mL of water is evaporated from 400 mL of 0.5 M aqueous salt solution, the resulting concentration is 1.0 M.
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What is emitted during gamma emission?
Electrons
Light
Alpha particles
Beta particles
Answer:c
Explanation:
Answer
Light
Explanation:
The gamma emission is an electromagnetic radiation, this kind of radiation come from the light.
In gamma ray emission, a gamma ray is photon of light. Given that light does not have mass or charge, the symbol we use to identify it is: 00γ. With two zeroes.
hope i helped
-lvr
The muscles of the body are part of the muscular system but would not operate without the _______ system providing the impulses that cause the muscles to act.
Answer:
The nervous system
Explanation:
The nervous system send messages from the brain to the muscles to move.
The nervous system, particularly the somatic nervous system, provides the impulses that enable the muscular system to function, allowing for a wide range of both voluntary and involuntary movements.
Explanation:The muscles of the body, part of the muscular system, would not function without the nervous system providing the impulses that cause the muscles to act. This is particularly true for the skeletal muscles, which completely depend on signaling from the nervous system to work properly.
Our nervous system is divided into the somatic nervous system (SNS) and the autonomic nervous system, with the SNS responsible for the contraction of our skeletal muscles. This mechanism enables a wide range of voluntary and involuntary movements, like standing, walking, running, grasping items, and reflex actions; some of which happen automatically due to habit learning or procedural memory.
Responses can be voluntary, such as the contraction of skeletal muscles, or involuntary like the contraction of smooth muscles, regulation of cardiac muscles, and activation of glands.
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Element named for a university on the west coast of the us
Answer is hope this helps
Answer:
Cf
Explanation:
californium
The humidity in a local area is high and the temperature drops. These conditions might cause A. dry weather. B. ocean currents. C. rainy weather. D. colder winters.
Answer:
C. rainy weather
Explanation:
Rainy weather or other precipitation occurs when moist (humid) air is cooled below its dew point.
Cold winters are part of the long term climate of an area.
These conditions might cause a rainy weather. Therefore, the correct option is option C among all the given options
What is humidity?Humidity refers to the quantity of air that contains water vapor. Water vapor, the gaseous component of water, is frequently invisible to the eye. The humidity predicts the presence for precipitation, dew, and fog. Humidity is affected by the pressure as well as temperature of the system in issue.
When a corresponding quantity of vaporized water is present, cold air has a higher relative humidity than warm air. Another important variable is the dew point. More water vapor is necessary as the temperature rises until saturation is attained. The humidity in a local area is high and the temperature drops. These conditions might cause a rainy weather.
Therefore, the correct option is option C.
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Which is the best description of hydrogen bonding? Which is the best description of hydrogen bonding? the association between a hydrogen atom which is somewhat positive because it is bonded to a small electronegative atom and an atom of O, N or F on another molecule the association between hydrogen of one molecule and a region of another molecule which has become negative due to temporary shifts in electron density the unique chemical bonds between hydrogen and any other atom in the same molecule the temporary attraction between hydrogen atoms on different molecules resulting from shifts in electron density the polarity associated with a bond between hydrogen and a small electronegative atom to which it is bonded
Answer:
The best description of hydrogen bonding is the association between a hydrogen atom which is somewhat positive because it is bonded to a small electronegative atom and an atom of O, N or F on another molecule. (this is the first choice)Explanation:
Hydrogen bonding is a special type of intermolecular force due to dipole - dipole atraction.
In order to the hydrogen bonding can be formed, the hydrogen atom in a molecule must be covalently bonded to an atom of oxygen (O), nitrogen (N), or fluor (F).
The most common example of hydrogen bonding is that of water molecules (H₂0).
Due to the relatively high electronegativity difference between hydrogen (H) and oxygen (O) atoms, each H will bear a high partial positive charge (δ+) and each O will have a high partial negative charge (δ-). Thus, the negative end of each H₂O molecule will be attracted to the negative part of other (neighbor) H₂O molecule. This attraction is the hydrogen bonding and is responsible for many important special properties of water.
Hydrogen bonding is the association between a weakly positive hydrogen atom already bonded to one electronegative atom and an atom of O, N or F on another molecule. It is a weak interaction that occurs due to the attraction between opposite partial charges.
Explanation:The best description of hydrogen bonding is the association between a hydrogen atom which is somewhat positive because it is bonded to a small electronegative atom and an atom of O, N or F on another molecule. This occurs when a weakly positive hydrogen atom already bonded to one electronegative atom is attracted to another electronegative atom from another molecule. Hydrogen bonding is a weak interaction, but it plays a significant role in many chemical and biological processes.
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How do you do 35 and 36?
Answer:
Q35 (C); Q36 (B)
Explanation:
Li₃N + 2H₂ ⇌ 2LiNH₂ + 2LiH; ΔH° = -192 kJ·mol⁻¹
Q35. Reaction rate
The reaction is slow below because it has a high activation energy.
ΔH, ΔS, and ΔG determine the position of equilibrium and the spontaneity of the reaction, not its rate.
Q36. Maximizing amount of H₂
The reaction is exothermic. According to Le Châtelier's Principle, increasing the temperature will shift the position of equilibrium to the left and increase the amount of hydrogen.
Increasing the pressure will shift the position of equilibrium to the side with fewer moles of hydrogen.
Decreasing the pressure will shift the position of equilibrium to the side with more moles of hydrogen.
The correct answer is (B) increasing the temperature and decreasing the pressure .
What is the nucleon a number of carbon-14?
Answer:
The nucleon number of carbon-14 is 14Explanation:
Nucleons are the particles that are in the nucleus of the atom, i.e. protons and neutrons.
So, the nucleon number is the number of protons and neutrons.
Other name for nucleon number is mass number, and it is represented by the letter A:
nucleon number = mass number = A = protons + neutrons.
Carbon-14 is the particular name, indicating the mass number, of the isotope of carbon with mass number 14.
So, the nucleon number of carbon-14 is indicated in its name, and it is 14.
The name carbon-14 identifies completely the isotope because, the atomic number of carbon is the same for every atom (isotope) of carbon:
Atomic number = number of protons = Z = 6Mass number = A = 14Number of neutrons = N = Z - A = 14 - 6 = 8Which sources are reliable? Check all that apply.
an article discussing mineral resources written by the United States Geological Survey
a blog discussing sources of alternate energy written by a high school student
an advertisement for guided hikes and tours in Camping magazine
a study describing clinical trials of a new medication in the Journal of Medicinal Chemistry
an entry about common uses of metals in an encyclopedia that can be edited by the general public
Answer:
an article discussing mineral resources written by the United States Geological Surveya study describing clinical trials of a new medication in the Journal of Medicinal Chemistry
Answer:
An article discussing mineral resources written by the United States Geological Survey.
A study describing clinical trials of a new medication in the Journal of Medicinal Chemistry.
Explanation:
A reliable source can be define as the source of information which can be used for the purpose of research. The reliable source should be thorough, well reasoned and must be supported by the evidences. It can be based on experimental trials and outcomes of the previous research. It can be proved by the authentic organization and institution.
The following are the examples of reliable sources:
An article discussing mineral resources written by the United States Geological Survey.: This is the authentic reliable source as the information is provided by recognized survey organization.
A study describing clinical trials of a new medication in the Journal of Medicinal Chemistry.: This is reliable source because the information is provided on the basis of the clinical trials the results of which will be reliable as in journals only the reliable information is presented.