Element R has three isotopes. The isotopes are present in 0.0825, 0.2671, and 0.6504 relative
abundance. If their masses are 81, 115, and 139 respectively, calculate the atomic mass of element
R. (No decimals).
The average atomic mass of the element R that has three isotopes is 127.805.
How to calculate average atomic mass?Average atomic mass is the weighted average of the atomic masses of the naturally occurring isotopes of an element.
The average atomic mass of an element can be calculated by summing up the product of the percent abundance and masses of each isotope as follows;
Average atomic mass of R = (0.0825 × 81) + (0.2671 × 115) + (0.6504 × 139)
Average atomic mass = 6.6825 + 30.7165 + 90.4056 = 127.805
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please help with 1 i would like to see the work please
Answer:
D. 0.063 mol
Explanation:
We can calculate the number of moles by using the definition of molarity:
Molarity = moles / litersAs we are given both the molarity and the volume:
0.05 M = moles / 1.25 LWe can calculate the number of moles:
moles = 0.05 M * 1.25 Lmoles = 0.063 molThus the answer is option D.
which method is adopted in the seperation of lead chloride from water
Explanation:
by dissolving the mixture of lead sulphate and lead chloride in water we can separate the two. after dissolving the mixture on water lead sulphate can be obtained as the solid that 's left behind lead chloride can be recovered by evaporating.
The weak base ionization
constant (Kb) for C4H4N2 is
equal to
Answer:
A
Explanation:
The weak base ionization constant (Kb) for [tex]C_{4} H_{4} N_{2}[/tex] is equal to Option A.
Are weak foundations made of ionized?A weak foundation is a base that makes ionize only slightly in an aqueous solution. Remember that a foundation can be defined as an object, which receives a hydrogen ion from another object.
What is the kb of a weak foundation?To obtain an aqueous solution of a weak acid, the dissociation constant is called the acid ionization constant (Ka). Similarly, the constant equilibrium of a weak base reaction with water is the base ionization constant (Kb). In any conjugate acid-base pair, KaKb = Kw.
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The Earth's asthenosphere is a structural layer
A.
that is made of the crust and the uppermost part of the mantle.
B.
that is contained completely within the crust.
C.
that is contained completely within the upper mantle.
D.
that is made of the mantle and the uppermost part of the crust.
Answer:
Dont completly trust me here but i think its a but id try and wait for someone else just be careful
Explanation:
You rub a comb on your hair and then the comb is able to pick up pieces of paper. Explain why this happens
Answer:
This happened because,the comb was charged with static electricity when it was rubbed on your hair.
(¬_¬)ﾉ( ˘ ³˘)♥
If 50.0 g of silicon dioxide is heated with an excess of carbon, 27.9 g of silicon carbide is produced. What is the percent yield of the reaction
Answer: The percent yield of the reaction is 83.5 %
Explanation:
The given balanced equation is
[tex]SiO_2+3C\rightarrow SiC+2CO[/tex]
[tex]SiO_2[/tex] is the limiting reagent as it limits the formation of product and [tex]C[/tex] is the excess reagent.
According to stoichiometry :
60.08 g of [tex]SiO_2[/tex] produce = 40.11 of [tex]SiC[/tex]
Thus 50.0 of [tex]SiO_2[/tex] will produce=[tex]\frac{40.11}{60.08}\times 50.0=33.4[/tex] of [tex]SiC[/tex]
Experimental yield of SiC = 27.9 g
Percent yield = [tex]\frac{\text {Experimental yield}}{\text {theoretical yield}}\times 100=\frac{27.9g}{33.4g}\times 100=83.5\%[/tex]
Thus percent yield of the reaction is 83.5 %
The percent yield of 83.5 % of 50.0 g of silicon dioxide is heated with an excess of carbon, and 27.9 g of silicon carbide is produced in the reaction.
What is the chemical balance of the equation?
The chemical equations are balanced when the reactants react to form products. The reactants and products react in proper ratios and if they are not in ratio then we balance them by adding the required quantity in the reactants and the products.
The given balanced equation is
[tex]\rm SiO_2+3C---- > SiC+2CO[/tex]
[tex]SiO_2[/tex] is the limiting reagent as it limits the formation of product and is the excess reagent.
According to stoichiometry
60.08 g [tex]SiO_2[/tex] of produce = 40.11 of [tex]SiC[/tex]
Thus 50.0 of [tex]SiO_2[/tex] will produce= [tex]\dfrac{40.11}{60.08} \times 50=33.4\ SiC[/tex]
The experimental yield of SiC = 27.9 g
The percentage yield will be calculated as
[tex]\rm Percentage \ Yield = \frac{Experimental\ yield}{Theoretical \ yield }\times 100[/tex]
[tex]\rm Percentage \ yield =\dfrac{27.9}{33.49} \times 100=83.5[/tex]
Thus the percent yield of 83.5 % of 50.0 g of silicon dioxide is heated with an excess of carbon, and 27.9 g of silicon carbide is produced in the reaction.
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Element R has three isotopes. The isotopes are present in 0.0398, 0.1614, and 0.7988 relative
abundance. If their masses are 191, 180, and 143 respectively, calculate the atomic mass of element
R. (No decimals)
The atomic mass of element R is 151 (no decimals).
To calculate the atomic mass of element R, we need to consider the relative abundance of each isotope and its corresponding mass. The atomic mass is the weighted average of the masses of all the isotopes, taking into account their relative abundance.
Given:
Isotope 1: Relative abundance = 0.0398, Mass = 191
Isotope 2: Relative abundance = 0.1614, Mass = 180
Isotope 3: Relative abundance = 0.7988, Mass = 143
To calculate the atomic mass, we multiply the relative abundance of each isotope by its mass, and then sum up the results.
Atomic mass = (Relative abundance of Isotope 1 * Mass of Isotope 1) + (Relative abundance of Isotope 2 * Mass of Isotope 2) + (Relative abundance of Isotope 3 * Mass of Isotope 3)
Atomic mass = (0.0398 * 191) + (0.1614 * 180) + (0.7988 * 143)
Calculating the values:
Atomic mass = 7.6098 + 29.0256 + 114.6872
Atomic mass = 151.3226
Rounding to the nearest whole number, the atomic mass of element R is 151.
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15. Kinetic and potential energy both relate to
a. friction
a. heat
b. light
d. motion
Answer:
All forms of energy are either potential or kinetic energy. Potential refers to stored energy while kinetic is energy in motion.
Explanation:
hope help you pls thanks...
D is correct option
How many protons are in nitrogen
Answer:
Explanation:
There are 7 protons in nitrogen
7 TYPE OF NITRONGEN
. . .
why are electrical wires covered with plastic coating
Answer:
For safety.
Explanation:
Because uncovered wires are conductors, an electric current could damage someone if touched. Plastic and rubber are insulators, meaning that current cannot pass through them.
What is the entropy of this collection of training examples with respect to the positive class B. What are the information gains of A1 and A2 relative to the training dataset For A3, which is a continuous attribute, compute the information gain for every possible split. C. What is the best split (among A1,A2, and A3) according to the information gain
The data set is missing in the question. The data set is given in the attachment.
Solution :
a). In the table, there are four positive examples and give number of negative examples.
Therefore,
[tex]$P(+) = \frac{4}{9}$[/tex] and
[tex]$P(-) = \frac{5}{9}$[/tex]
The entropy of the training examples is given by :
[tex]$ -\frac{4}{9}\log_2\left(\frac{4}{9}\right)-\frac{5}{9}\log_2\left(\frac{5}{9}\right)$[/tex]
= 0.9911
b). For the attribute all the associating increments and the probability are :
[tex]$a_1$[/tex] + -
T 3 1
F 1 4
Th entropy for [tex]$a_1$[/tex] is given by :
[tex]$\frac{4}{9}[ -\frac{3}{4}\log\left(\frac{3}{4}\right)-\frac{1}{4}\log\left(\frac{1}{4}\right)]+\frac{5}{9}[ -\frac{1}{5}\log\left(\frac{1}{5}\right)-\frac{4}{5}\log\left(\frac{4}{5}\right)]$[/tex]
= 0.7616
Therefore, the information gain for [tex]$a_1$[/tex] is
0.9911 - 0.7616 = 0.2294
Similarly for the attribute [tex]$a_2$[/tex] the associating counts and the probabilities are :
[tex]$a_2$[/tex] + -
T 2 3
F 2 2
Th entropy for [tex]$a_2$[/tex] is given by :
[tex]$\frac{5}{9}[ -\frac{2}{5}\log\left(\frac{2}{5}\right)-\frac{3}{5}\log\left(\frac{3}{5}\right)]+\frac{4}{9}[ -\frac{2}{4}\log\left(\frac{2}{4}\right)-\frac{2}{4}\log\left(\frac{2}{4}\right)]$[/tex]
= 0.9839
Therefore, the information gain for [tex]$a_2$[/tex] is
0.9911 - 0.9839 = 0.0072
[tex]$a_3$[/tex] Class label split point entropy Info gain
1.0 + 2.0 0.8484 0.1427
3.0 - 3.5 0.9885 0.0026
4.0 + 4.5 0.9183 0.0728
5.0 -
5.0 - 5.5 0.9839 0.0072
6.0 + 6.5 0.9728 0.0183
7.0 +
7.0 - 7.5 0.8889 0.1022
The best split for [tex]$a_3$[/tex] observed at split point which is equal to 2.
c). From the table mention in part (b) of the information gain, we can say that [tex]$a_1$[/tex] produces the best split.
Determine the number of formula units in 48.0 grams of magnesium chloride (MgCl2)
Answer:
3.03 x 10²³ formula units
Explanation:
First we convert 48.0 grams of magnesium chloride into moles, using its molar mass:
48.0 g ÷ 95.21 g/mol = 0.504 mol MgCl₂Then we convert 0.504 moles into formula units, using Avogadro's number:
0.504 mol * 6.023x10²³ formula units/mol = 3.03x10²³ formula unitsA balloon is filled
with 35.0 L of
helium when the
temperature is
200K. If the tem-
perature rises to
450K, what is the
new volume of the
balloon?
Answer:
78.75L
Explanation:
According to Charle's Law:
V1/T1=V2/T2
35/200=V2/450
V2=(35*450)200
V2=78.75L
Which element had the smallest atomic radius
Answer:
helium is the answer
Explanation:
helium is the smallest element in francium is the largest hope this helps
Calculate the number of grams of Hydrogen required to produce 5.73 grams of water. 2H2+O2--->2H2O 2 grams 0.636 grams 1.2 gram 7.98 grams
Explanation:
32
2H
2
+O
2
→2H
2
O
Molecular mass of H
2
=2 g/mol
Molecular mass of O
2
=32 g/mol
From the balanced chemical equation,
2×2=4 g of hydrogen requires 32 g of Oxygen to react completely
Aqueous solutions containing approximately 3 percent(w/w) H2O2 are sold in drug stores as a disinfectant. Determination of the actual concentration of H2O2 in a bottle of peroxide solution was done by diluting 1.50 mL to 100 mL with water, acidifying with dilute H2SO4 and titrating with a 0.01411 M KMnO4 solution. 32.17 mL of the permangate solution was needed to reach the end point of the titration. What is the actual molar concentration of the H2O2 solution]
Answer:
0.01804 M KMnO4 Solution.
Explanation:
3 Percent(w/w) H2O2 Are Sold In Drug Stores As A Disinfectant. ... H2O2 In A Bottle Of Peroxide Solution Was Done By Diluting 1.50 ML To 100 ML With Water, Acidifying With Dilute H2SO4 And Titrating With A 0.01804 M KMnO4 Solution.
HELPP PLZ FAST WILL GIVE BRAINLIEST
Benzene, a nonpolar, colorless solute, is most commonly found in oil and is a major component in gasoline.
In which of these two solvents will benzene most likely dissolve?
Solvent
Characteristics
A
Carbon tetrachloride
• Colorless liquid, noncombustible
• Nonpolar
Ethanol
• Flammable, colorless liquid
• Polar
Methanol
• Distinctive odor; volatile, colorless liquid
• Polar
Cyclohexane
• Strong odor; flammable; colorless liquid
• Nonpolar
OA
OB
ОС
OD
If the solubility of salicylic acid is 77.8 g/L of water at 100oC and 1.4 g/L of water at 10oC, a) calculate the minimum amount (in mL) of boiling water necessary to dissolve 2.0 g of impure salicylic acid for recrystallization. b) If the solution is cooled to room temperature and then to 10oC with an ice/water bath, what is the maximum amount of solid salicylic acid isolated after vacuum filtration
Answer:
a. 25.7mL are necessaries.
b. 1.964g of salicylic acid can be isolated.
Explanation:
a. As the solubility of salicylicic acid in boiling water is 77.8g/L, to dissolve 2.0g of salicylic acid are necessaries:
2.0g * (1L / 77.8g) = 0.0257L =
25.7mL are necessariesb. Then, at 10°C the solution just can dissolve 1.4g/L, that is:
0.0257L * (1.4g/L) = 0.036g of salicylic acid are dissolved.
And will precipitate:
2.0g - 0.036g =
1.964g of salicylic acid can be isolatedIdentify the substance that has formula mass of 133.5amu.
(a) MgCI
b)SCI
c)BCI
D) AICI
The calculated formula masses to 133.5 amu, we find that the substance with a formula mass closest to 133.5 amu is (d) AlCl3. Therefore, the answer is option D.
To identify the substance with a formula mass of 133.5 amu, we need to calculate the formula mass of each given substance and compare it to 133.5 amu.
(a) MgCl2:
The formula mass of MgCl2 can be calculated by adding the atomic masses of magnesium (Mg) and chlorine (Cl).
Mg: atomic mass = 24.31 amu
Cl: atomic mass = 35.45 amu
Formula mass of MgCl2 = (24.31 amu) + 2(35.45 amu) = 95.21 amu
(b) SCl:
The formula mass of SCl can be calculated by adding the atomic masses of sulfur (S) and chlorine (Cl).
S: atomic mass = 32.07 amu
Cl: atomic mass = 35.45 amu
Formula mass of SCl = 32.07 amu + 35.45 amu = 67.52 amu
(c) BCl:
The formula mass of BCl can be calculated by adding the atomic mass of boron (B) and chlorine (Cl).
B: atomic mass = 10.81 amu
Cl: atomic mass = 35.45 amu
Formula mass of BCl = 10.81 amu + 35.45 amu = 46.26 amu
(d) AlCl3:
The formula mass of AlCl3 can be calculated by adding the atomic mass of aluminum (Al) and 3 times the atomic mass of chlorine (Cl).
Al: atomic mass = 26.98 amu
Cl: atomic mass = 35.45 amu
Formula mass of AlCl3 = 26.98 amu + 3(35.45 amu) = 133.78 amu. Option D
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8. How much heat will be released when
18.6 g of hydrogen reacts with excess O2
according to the following equation?
Answer:
15 is it
Explanation:
Iron has a density of 7.87 g/cm^3. What is the mass of 55.2 cm^3 of iron?
Answer: Formula: Mass = (Volume)(Density)
Iron Density = 7.87 g/cm^3
Volume of Iron = 55.2 cm^3
Mass=(V)(D)
Mass= (55.2 cm^3) x (7.87 g/cm^3)
Mass= 434,42 g
Explanation:
Iron has a density of 7.87 g/cm³. 434,42 g is the mass of 55.2 cm³ of iron.
What do you mean by density ?The term density is defined as the measurement of how closely a material is packed together.
It is also defined as the mass per unit volume. Density Symbol is D or ρ Density Formula is ρ = m/V, where ρ is the density, m is the mass of the object and V is the volume of the object.
Density is an important because it allows us to find out what substances will float and what substances will sink when placed in a liquid.
Formula:
Mass = (Volume)(Density)
Given:
Iron Density = 7.87 g/cm³
Volume of Iron = 55.2 cm³
Mass=(V)(D)
Mass= (55.2 cm³) x (7.87 g/cm³)
Mass= 434,42 g
Thus, Iron has a density of 7.87 g/cm³. 434,42 g is the mass of 55.2 cm³ of iron.
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Wich stament describes to organ systems working together to get rid of waste played by cells
Answer:
C. Kidneys filter wastes from the bloodstream and produce urine
Explanation:
Easy question please help.
Answer:
1 km an hour
Explanation:
i mean its pretty easy like you said if at 4 hours its traveled 4 km then its going 1 km an hour and at 10 its gone 10 km
At some temperature for the equilibrium PX3(g) + X2(g) # PX5(g) the equilibrium constant is 0.74. At the same temperature the equilibrium constant for PX5(9) + PX3(g) X2(g) is
Answer: The equilibrium constant for [tex]PX_5(g)\rightarrow PX_3(g)+X_2(g)[/tex] is 1.35
Explanation:
Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as [tex]K_c[/tex]
For the given chemical reaction:
[tex]PX_3(g)+X_2(g)\rightarrow PX_5(g)[/tex]
The expression for [tex]K_c[/tex] is written as:
[tex]K_c=\frac{[PX_5]^1}{[PX_3]^1[X_2]^1}[/tex]
[tex]0.74=\frac{[PX_5]^1}{[PX_3]^1[X_2]^1}[/tex]
For the reverse chemical reaction:
[tex]PX_5(g)\rightarrow PX_3(g)+X_2(g)[/tex]
The expression for [tex]K_c'[/tex] is written as:
[tex]K_c'=\frac{[PX_3]^1[X_2]^1}{[PX_5]^1}[/tex]
[tex]K_c'=\frac{1}{K_c}=\frac{1}{0.74}=1.35[/tex]
The equilibrium constant for [tex]PX_5(g)\rightarrow PX_3(g)+X_2(g)[/tex] is 1.35
what is the molecular geometry for CH2Br2?
HCH bond angle is ~110 degrees.
5. How many grams of Br is needed to make 1000.g of a 2.0ppm solution?
Answer:
2.0 × 10⁻³ g
Explanation:
Step 1: Given data
Mass of solution: 1000. g (1.000 kg)Concentration of Br₂: 2.0 ppmStep 2: Calculate the mass of Br₂ required to prepare the solution
The concentration of Br₂ is 2.0 ppm, that is, there are 2.0 mg of Br₂ per kilogram of solution. The mass of Br₂ required to prepare 1.000 kg of solution is:
1.000 kg Solution × 2.0 mg Br₂/1 kg Solution = 2.0 mg
Step 3: Convert the mass to grams
We will use the conversion factor 1 g = 1000 mg.
2.0 mg × 1 g/1000 mg = 2.0 × 10⁻³ g
how many mg are in 125ml of
phosphoric acid?
Answer:
125000mg
Explanation:
1ml = 1000mg
125(1000) = 125000mg
What is the source of the forces that cause this plate movement
Convection currents in the mantle, I got it right on a p e x
Why do scientists think that liquid water might have once existed on Mars?
Answer: The discovery of three buried lakes. Scientists think that a long time ago there were lakes and rivers, etc on Mars. Now of course, you can't see any visible water sources on the surface.
Answer:
Almost all water on Mars today exists as ice, though it also exists in small quantities as vapor in the atmosphere.[5] What was thought to be low-volume liquid brines in shallow Martian soil, also called recurrent slope lineae may be grains of flowing sand and dust slipping downhill to make dark streaks.The only place where water ice is visible at the surface is at the north polar ice cap. Abundant water ice is also present beneath the permanent carbon dioxide ice cap at the Martian south pole and in the shallow subsurface at more temperate conditions. More than 5 million km3 of ice have been detected at or near the surface of Mars, enough to cover the whole planet to a depth of 35 meters. Even more ice is likely to be locked away in the deep subsurface.
Some liquid water may occur transiently on the Martian surface today, but limited to traces of dissolved moisture from the atmosphere and thin films, which are challenging environments for known life. No large standing bodies of liquid water exist on the planet's surface, because the atmospheric pressure there averages just 600 pascals , a figure slightly below the vapor pressure of water at its melting point; under average Martian conditions, pure water on the Martian surface would freeze or, if heated to above the melting point, would sublime to vapor. Before about 3.8 billion years ago, Mars may have had a denser atmosphere and higher surface temperatures, allowing vast amounts of liquid water on the surface, possibly including a large ocean that may have covered one-third of the planet.Water has also apparently flowed across the surface for short periods at various intervals more recently in Mars' history. Aeolis Palus in Gale Crater, explored by the Curiosity rover, is the geological remains of an ancient freshwater lake that could have been a hospitable environment for microbial life.Many lines of evidence indicate that water ice is abundant on Mars and it has played a significant role in the planet's geologic history.The present-day inventory of water on Mars can be estimated from spacecraft images, remote sensing techniques (spectroscopic measurements, radar, etc.), and surface investigations from landers and rovers.Geologic evidence of past water includes enormous outflow channels carved by floods, ancient river valley networks, deltas and lakebeds,and the detection of rocks and minerals on the surface that could only have formed in liquid water. Numerous geomorphic features suggest the presence of ground ice (permafrost)and the movement of ice in glaciers, both in the recent past and present. Gullies and slope lineae along cliffs and crater walls suggest that flowing water continues to shape the surface of Mars, although to a far lesser degree than in the ancient past.Although the surface of Mars was periodically wet and could have been hospitable to microbial life billions of years ago, the current environment at the surface is dry and subfreezing, probably presenting an insurmountable obstacle for living organisms. In addition, Mars lacks a thick atmosphere, ozone layer, and magnetic field, allowing solar and cosmic radiation to strike the surface unimpeded. The damaging effects of ionizing radiation on cellular structure is another one of the prime limiting factors on the survival of life on the surface. Therefore, the best potential locations for discovering life on Mars may be in subsurface environments. Large amounts of underground ice have been found on Mars; the volume of water detected is equivalent to the volume of water in Lake Superior. In 2018, scientists reported the discovery of a subglacial lake on Mars, 1.5 km (0.93 mi) below the southern polar ice cap, with a horizontal extent of about 20 km (12 mi), the first known stable body of liquid water on the planet.Understanding the extent and situation of water on Mars is vital to assess the planet’s potential for harboring life and for providing usable resources for future human exploration. For this reason, "Follow the Water" was the science theme of NASA's Mars Exploration Program (MEP) in the first decade of the 21st century. NASA and ESA missions including 2001 Mars Odyssey, Mars Express, Mars Exploration Rovers (MERs), Mars Reconnaissance Orbiter (MRO), and Mars Phoenix lander have provided information about water's abundance and distribution on Mars.Mars Odyssey, Mars Express, MRO, and Mars Science Lander Curiosity rover are still operating, and discoveries continue to be made.