Answer:
ggggggggggggg
Explanation:
gggggggggggthyjum
Isotopes are: A. are only theoretical. B. only formed in laboratories. C. found in nature. D. found in the nuclear reactions in stars but not on Earth.
Answer:
B. only formed in laboratories
Explanation:
i know
Isotopes are only formed in Laboratories. hence, Option (B) is correct.
What are Isotopes ?
Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element is known as Isotope.
Isotopes are two or more types of atoms that have the same atomic number and position in the periodic table, and that differ in nucleon numbers due to different numbers of neutrons in their nuclei.
Therefore, Isotopes are only formed in Laboratories. hence, Option (B) is correct.
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what is the zeff of carbon
Answer:
Explanation:
The steps to calculate the Zeff is :
1) Write the electronic configuration.
Carbon: 1s2 2s2 2p2
Oxygen: 1s2 2s2 2p4
2) there are two core electrons in each atom and four in carbon and six in oxygen.
1s) (2s2p)
3) as mentioned the shielding of electrons within the same shell is negligible.
4) for electron of s or p orbital the shielding contribution by the electrons having a principal quantum number less by one would be 0.85 each. And all electrons further left would contribute an amount of 1.0 each.
5) For oxygen:
Zeff = Z - S
S = 2X0.85 = 1.7
Zeff = 8- 1.7 = 6.3
For carbon
Zeff = Z - S
S = 2X0.85 = 1.7
Zeff = 6- 1.7 = 4.3
milk has a pH of 6.0 and household ammonia has a pH of 12.0. How much more acidic is milk than ammonia
60 I think bcz if there is 1&2 they differ 10 times
The milk has a pH of 6.0 and household ammonia has a pH of 12.0. then milk will be 6 times milk acidic than ammonia.
What is pH?The pH scale, which previously stood for "potential of hydrogen," would be used to describe how acidic or basic an aqueous solution is.
What is an acidic solution?More hydrogen ions are present in an acidic solution than it was in pure water.
It is given then,
[tex](milk)pH_{1} = 6\\(ammonia)pH_{2} = 12[/tex]
The concentration of hydrogen ions can be calculated by using the formula:
[tex][H^{+}] = 10^{-pH}[/tex]
By putting the value of given data in the above equation.
[tex][H^{+}_{milk} ] / H^{+}_{ammonia}= 10^{-6}/10^{-12}\\ = 10^{6} = 6[/tex]
We get that, milk will be 6 times more acidic than ammonia.
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Determine which choice is an example of an endothermic process.
O A. Lighting a match
B. Respiration
C. Running a gas engine
D. Baking bread
Answer:
D. Baking bread
Explanation:
In this process, energy is absorbed and in an endothermic process energy is absorbed too.
Baking bread is an example of an endothermic process, therefore option (d) is correct .
What do you mean by endothermic process ?Endothermic reactions are chemical processes in which the reactants absorb heat from the environment to produce products.
An endothermic reaction is accompanied by an absorption of heat.
Endothermic reactions cause a cooling effect by lowering the temperature of the surrounding environment.
A decrease in temperature can be observed with the progression of the reaction. The reaction is non-spontaneous in endothermic reactions .
Baking bread is an example of an endothermic process, hence option (d) is correct .
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If the starting material has no stereogenic centers, when carbonyl compounds are reduced with a reagent such as LiAlH4 or NaBH4 and a new stereogenic center is formed, what will the composition of the product mixture be?
A) Forms a racemic mixture of the two possible enantiomers.
B) Forms more of one enantiomer than another because of steric reasons around the carbonyl.
C) Forms more of one enantiomer than another depending on the temperature of the reaction.
D) Forms different products depending on the solvent used.
Answer:
A) Forms a racemic mixture of the two possible enantiomers
When carbonyl compounds are reduced with a reagent such as LiAlH₄ or NaBH₄ and new stereogenic center is formed chemical change will lead to products that form a racemic mixture of the two possible enantiomers.
What is a chemical change?
Chemical changes are defined as changes which occur when a substance combines with another substance to form a new substance.Alternatively, when a substance breaks down or decomposes to give new substances it is also considered to be a chemical change.
There are several characteristics of chemical changes like change in color, change in state , change in odor and change in composition . During chemical change there is also formation of precipitate an insoluble mass of substance or even evolution of gases.
There are three types of chemical changes:
1) inorganic changes
2)organic changes
3) biochemical changes
During chemical changes atoms are rearranged and changes are accompanied by an energy change as new substances are formed.
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PLEASE HELP!!
this is on USAtestprep
a)
b)
c)
d)
Answer:
silicon dioxide /C
Explanation:
it can form thousands of covalent bonds between it's silicon and Oxygen due to it's macromolecular structure
The sugars can be classified as either aldoses or ketoses.
a. True
b. Fasle
Discuss the action of sodium with a) Ammonia b) non-metals
Answer:
i hope ammonia is the correct answer
Which of the following represents a physical change?
Answer:
» Water evaporating to gas.
» Solid subliming to gas.
» Water freezing to solid.
» Solid melting to liquid.
Explanation:
[tex]{ \underline{ \blue{ \sf{christ \:† \: alone }}}}[/tex]
a 67.5 L sample of gas at 27.6 °c and 383.1mm hg expands to 244.2 L at 4.7 °c. what is the new gas pressure.
a 97.8
b 18.0
c 115
d 1.65
Answer:
a well well well all el well eto eto rup wp will rup ei well dll alsof well po team app app app well piz wmv epic enz
A sample of water at 21.5°C required an input of 1.69 x 104 of heat to reach its boiling point, 100.0 °C. What was the mass of the
water?
Three bonding pairs around a central atom results in a ________. A. octahedral B. trigonal planar compound C. tetrahedral compound D. linear compound
Answer:
B
Explanation:
because it is a trigonal planar compound
Three bonding pairs around a central atom results in a trigonal planar compound. Option B is correct.
In a trigonal planar arrangement, the central atom is surrounded by three bonding pairs of electrons, forming a flat, triangular shape. The bond angles between the bonding pairs are approximately 120 degrees.
This molecular geometry is observed when a molecule has a central atom with three bonded pairs and no lone pairs. Examples of compounds with trigonal planar geometry include boron trifluoride (BF₃) as well as formaldehyde (H₂CO).
The other options are not correct for a molecule with three bonding pairs;
Octahedral refers to a molecular geometry with six bonding pairs around a central atom.
Tetrahedral corresponds to a molecular geometry with four bonding pairs around a central atom.
Linear represents a molecular geometry with two bonding pairs around a central atom.
Hence, B. is the correct option.
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What volume of 6.9 M NaOH is needed to completely titrate 0.42 L of 2.39 M phosphoric acid according to
the equation:
H3PO4(aq) + 3NaOH(aq) + Na3PO4(aq) + 3H2O(aq)
A) O 0.05 L
B) O6.93 L
C) O0.44 L
D) 03.01 L
E) 436.43 L
Taking into account the definition of molarity and the stoichiometry of the reaction, the correct option is option C) 0.44 L of 6.9 M NaOH is needed to completely titrate 0.42 L of 2.39 M phosphoric acid.
The balanced reaction is:
H₃PO₄ (aq) + 3 NaOH (aq) → Na₃PO₄ (aq) + 3 H₂O(aq)
Then, by stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:
H₃PO₄: 1 mole NaOH: 3 moles Na₃PO₄: 1 mole H₂O: 3 molesMolarity is the number of moles of solute that are dissolved in a given volume.
Molarity is determined by:
[tex]Molarity=\frac{number of moles of solute}{volume}[/tex]
Molarity is expressed in units [tex]\frac{moles}{liter}[/tex].
In this case, 0.42 L of 2.39 M phosphoric acid reacts. So, by definition of molarity, the number of moles that participate in the reaction is calculated as:
[tex]2.39 \frac{moles}{liter}=\frac{number of moles of phosphiric acid}{0.42 liters}[/tex]
Solving:
number of moles of phosphiric acid= 2.39 [tex]\frac{moles}{liter}[/tex]* 0.42 liters
number of moles of phosphiric acid= 1.0038 moles ≅ 1 mole
Approaching 1 mole of the amount of phosphoric acid required, then by stoichiometry of the reaction, 3 moles of NaOH are necessary to react with 1 mole of the acid.
Then by definition of molarity and knowing that 6.9 M NaOH is needed, you can calculate the necessary volume amount of NaOH by:
[tex]6.9 \frac{moles}{liter} =\frac{3 moles}{volume}[/tex]
Solving:
6.9 [tex]\frac{moles}{liter}[/tex]* volume= 3 moles
[tex]volume=\frac{3 moles}{6.9\frac{moles}{liter} }[/tex]
volume= 0.44 L
The correct option is option C) 0.44 L of 6.9 M NaOH is needed to completely titrate 0.42 L of 2.39 M phosphoric acid.
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9.7300x10^2 + 9.8700x10^3
? × 10^?
Answer:
19.6 x 10⁵
1.96 x 10⁶
I hope it's helps you
If sodium chloride (NaCl) is dissolved in water, how will the vapor pressure of the water be affected?
A. The vapor pressure will be raised, making it more easier to boil.
B. The vapor pressure will be raised, making it more difficult to boil.
C. The vapor pressure will be lowered, making it easier to boil.
D. The vapor pressure will be lowered, making it more difficult to boil.
The vapor pressure will be lowered, making it more difficult to boil If sodium chloride (NaCl) is dissolved in water. Hence, option D is correct.
What is vapor pressure?It can be defined as the pressure exerted by a vapor with its condensed phases in a closed system at a given temperature show the equilibrium vapor is a well-known measure of a liquid evaporation rate.
The vapor pressure of a liquid is the point at which equilibrium pressure is reached in a closed container. The molecules leaving the liquid and going into the gaseous phase and molecules leaving the gaseous phase and entering the liquid phase.
It is measured in the standard units of pressure the international system of units. Pressure as a derived unit with the dimension of force per area and designate the Pascal (Pa) as its standard unit.
When common salt is dissolved in water boiling point of a solution increases the boiling point of a substance is the temperature at which it will be lowered, making it more difficult to boil If sodium chloride (NaCl) is dissolved in water. Hence, option D is correct.
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Explain why it is not advisable to add water to acid when
mixing them
Answer:
Consequence
you form an extremely concentrated solution of acid initially.and the solution may boil very violently, splashing concentrated acid. I hope this helped! :)Which one of the following is not matches the organelle with its function
Answer:
rip there isnt a photo
Explanation:
i do know a lot about cells tho lol
a=bcd in order to solve the equation above for b you must multiply both sides of the equation by the same expression
a x _ = bcd x _
the results equation is:
b=
Both sides of the equation must be multiplied by 1/cd to give the following equation: b = a/cd
The following equation was given in this question: a = bcd. This means that a = b × c × d. Hence, to make "b" the subject of the formula, we have to eliminate "cd" from the side of the equation with "b". To do that, we multiply both sides of the equation with the same expression as follows:a x 1/cd = bcd x 1/cd
"cd" cancels out "cd" in the right side of the equation to result to:a/cd = b
Therefore, b = a/cd
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Describe ask a question in in sincence
Answer:
why do we dream
Explanation:
Which electron configuration matches this model?
0 1s22s2p2
0 1s²2s2p3
O 1s²2s²2p4
1s22s²2p5
Answer:
1s2 2s2 2p5
is the correct answer
Explanation:
Hi there!
From the figure;
We can figure out that the atomic number is 7.
So;
Option A: 1s² 2s² 2p²
Sum of the powers of variable is just 6. So, it's not answer.
Option B: 1s²2s²2p³
Sum of the powers of variable is 7. So it's the answer
Option C: 1s²2s²2p⁴
Sum of the powers of variable is 8. So, it's not answer.
Option D: 1s²2s²2p⁵
Sum of the powers of variable is 9. So, it's not the correct answer.
Therefore, answer is option B.
Hope it helps!
what is the bond energy required to break one mole of carbon-carbon bonds
Answer:
100 kcal of bond energy
Could someone help with this? Much appreciated!
Answer:
The 3rd answer down.
Na²O (sodium oxide) will be a base when exposed to water H²O
Explanation:
Sodium Oxide Na²O, will become Sodium Hydroxide after being exposed to water (at 80% I believe).
The oxygen ion in Na²O has 2 extra electrons which makes it highly charged and very attractive to hydrogen ions. The attraction is so strong that when Na²O comes in contact with H²O, the O(-2) strips off a hydrogen from water, forming 2 x OH ions which of course are still strongly basic.
A gas within a piston–cylinder assembly undergoes an isothermal process at 400 K during which the change in entropy is −0.3 kJ/K. Assuming the ideal gas model for the gas and negligible kinetic and potential energy effects, evaluate the work, in kJ.
Answer:
W = -120 KJ
Explanation:
Since the piston–cylinder assembly undergoes an isothermal process, then the temperature is constant.
Thus; T1 = T2 = 400K
change in entropy; ΔS = −0.3 kJ/K
Formula for change in entropy is written as;
ΔS = Q/T
Where Q is amount of heat transferred.
Thus;
Q = ΔS × T
Q = -0.3 × 400
Q = -120 KJ
From the first law of thermodynamics, we can find the workdone from;
Q = ΔU + W
Where;
ΔU is Change in the internal energy
W = Work done
Now, since it's an ideal gas model, the change in internal energy is expressed as;
ΔU = m•C_v•ΔT
Where;
m is mass
C_v is heat capacity at constant volume
ΔT is change in temperature
Now, since it's an isothermal process where temperature is constant, then;
ΔT = T2 - T1 = 0
Thus;
ΔU = m•C_v•ΔT = 0
ΔU = 0
From earlier;
Q = ΔU + W
Thus;
-120 = 0+ W
W = -120 KJ
Which phenomenon explained below is an example of deposition?
Select the correct answer below:
A) Hail is formed from water droplets lifted by air currents to an altitude where they turn into pellets of ice.
B) Frost forms when cold evening temperatures convert the humidity in the air to thin layers of ice on the ground.
C) In the winter, the top few inches of a pond turn to ice.
D) The visible cloud arising from a boiling tea kettle is not actually steam, but droplets of liquid water that form as the
steam cools in the air.
Answer:
b
Explanation:
deposition is when water turns from gas to solid. b is the only one that fits
Deposition is frost forms when cold evening temperatures convert the humidity in the air to thin layers of ice on the ground.
What is deposition?Deposition is a process that involves collection of large mass or when mean distance between molecules are reduced. It can also be explained as gathering of substances together to form a larger mass.
Therefore, the phenomenon explained in the given example about deposition is frost forms when cold evening temperatures convert the humidity in the air to thin layers of ice on the ground.
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5. Calcule las concentraciones cuando se alcanza el equilibrio si partimos de unas concentraciones iniciales [A]=[B]=1M ; [C]=[D]=0M y una constante de equilibrio de 5.
Las concentraciones en el equilibrio para la reacción química presentada son:
[tex][A] = [B] = 1-x = 1-0.69 = 0.31 M\\[C] = [D] = x = 0.69 M[/tex]
Consideremos la siguiente reacción química genérica:
A + B ⇄ C + D
Para calcular las concentraciones en el equilibrio, debemos construir una Tabla ICE. Cada fila representa una instancia (Inicial, Cambio, Equilibrio) y la completamos con la concentración o cambio de concentración ("x" para concentraciones desconocidas). Como inicialmente no hay productos, la reacción se desplazará hacia la derecha para alcanzar el equilibrio.
A + B ⇄ C + D
I 1 1 0 0
C -x -x +x +x
E 1-x 1-x x x
La constante de equilibrio, Kc, es:
[tex]Kc = 5 = \frac{[C][D]}{[A][B]} = \frac{x^{2} }{(1-x)^{2} } \\\sqrt{5} = x/1-x\\x = 0.69[/tex]
Las concentraciones en el equilibrio son:
[tex][A] = [B] = 1-x = 1-0.69 = 0.31 M\\[C] = [D] = x = 0.69 M[/tex]
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How would you expect cesium, Cs, to react with water? explaining your reasoning.
Answer:
Caesium reacts rapidly with water to form a colourless basic solution of caesium hydroxide (CsOH) and hydrogen gas (H2).
Explanation:
The reaction continues even when the solution becomes basic. The resulting solution is basic because of the dissolved hydroxide. The reaction is exothermic.
An ionic bond is a bond
Answer:
That involve the complete transfer of an electron from one atom of an element to another
18. What is the density of a substance with a mass of 0.90 kg and a volume of 1.2 mL?
21. An oxygen tank in the lab has a pressure of 12 atm at 250C. If the pressure inside the gas tank exceeds 25 atm, the tank will explode. If a fire occurs in the lab, raising the temperature of the gas inside the cylinder to 398oC, will the tank explode?
Answer:
fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
Explanation:
I 100 mL o a pharmaceutical preparation contains 20 mL o a 50% w/v solution o benzalkonium chloride, what is the percent strength o that agent in the solution
The percentage strength of the agent is 10 %
Since 100 mL of a pharmaceutical preparation contains 20 mL of a 50% w/v solution of benzalkonium chloride, we desire to find the percentage strength of that agent in the 100 mL solution.
Let C₁ = percentage strength of 20 mL solution = 50 %, V₁ = initial volume = 20 mL, C₂ = percentage strength of agent in 100 mL solution and V₂ = final volume = 100 mL.
Since the initial quantity of agent in 20 mL solution equals the final quantity of agent in 100 mL solution, we have that
C₁V₁ = C₂V₂
So, making C₂ = percentage strength of agent in 100 mL solution the subject of the formula, we have
C₂ = C₁V₁/V₂
Substituting the values of the variables into the equation, we have
C₂ = C₁V₁/V₂
C₂ = 50 % × 20 mL/100 mL
C₂ = 50 % × 0.2
C₂ = 10 %
So, the percentage strength of the agent is 10 %.
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Draw all four products when the following compound undergoes dehydrohalogenation and rank them in terms of stability. Which product do you expect to be the major product?
Answer:
2 Methyl pent 2 ene
