Answer:
A ; 20g of water has the least number of molecules
Explanation:
Here, we want to know which of the options represent the least number of molecules;
To calculate this, we are going to first calculate the number of moles using the formula below;
Number of moles = mass/molar mass
Then from the number of moles, we can calculate the number of molecules by multiplying the number of moles by 6.02 * 10^23 molecules
Let’s proceed;
a. That will be 20/18.02 = 1.1099 moles
1.1099 * 6.02 * 10^23 = 6.68 * 10^23 molecules
b. That will be 77/16.06 = 4.8 moles
4.8 * 6.02 * 10^23 = 2.89 * 10*24 molecules
c. That will be 68/42.09 = 1.62 moles
1.62 * 6.02 * 10^23 = 9.73 * 10^23 molecules
d. That will be 100/44.02 = 2.27 moles
2.27 * 6.02 * 10^23 = 1.37 * 10^24 molecules
e. That will be = 84/20.01 = 4.2 moles
4.2 * 6.02 * 10^23 = 2.53 * 10^24 molecules
From all the values obtained, the lowest is 20g of water
Which of the following is an example of a chemical change
A. apple slices turn brown
B. toast burns
C. silver tarnishes
D. all of these are chernical changes
Answer:
D. all of these are chemical changes
There are________
neutrons in the stable isotope of rhenium (Re-
185)
A.134
B.90
C.125
D.110
There are 110 neutrons in the stable isotope of rhenium. The correct option is D.
What are neutrons?A neutron is a subatomic particle that exists in the nucleus of all atoms except simple hydrogen. The name of the particle comes from the fact that it has no electrical charge; it is neutral. Neutrons have a very high density.
With the exception of the single-proton hydrogen nucleus, nuclei require neutrons to be stable. Neutrons are abundantly produced during nuclear fission and fusion.
Through mainly the process of fission, fusion, as well as neutron capture processes, they are a major contributor to the nucleosynthesis of chemical elements within stars.
The element rhenium-185 is made up of 75 protons, 110 neutrons, and 75 electrons. The element rhenium-187 is made up of 75 protons, 112 neutrons, and 75 electrons.
Thus, the correct option is D.
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Calculate the atomic mass of element "X" if it has 2 naturally occurring isotopes with the following masses and natural abundances. X−107 106.90509 amu 51.84%X−109 108.90476 amu 48.46%
Answer:
Using my (not very precise) periodic table, I get the mass of Ag as 107.87
Explanation:
This must be a combination of these two isotopes. So the % of the other isotope must be 48.16%.
To work with these percentages in an equation I'll use them as decimals.
So now I can start putting them into an equation:
107.87 = ( 106.905 ⋅ 0.5184 ) + ( x ⋅ 0.4816 )
Because both of the isotope masses, multiplied by their percentage, would give us the overall average mass.
107.87 = 55.419552 ⋅ ( x ⋅ 0.4816 )
Worked out the brackets that we can work out, and then rearrange to give:
107.87 − 55.419552 = ( x ⋅ 0.4816 )
Again rearrange:
52.450448 = ( x ⋅ 0.4816 )
And final rearranging:
x = 52.450448 - 0.4816
x
=
108.909
(using same sig figs as given in question)
You probably want to work through that again using your periodic table value for Ag.
a race car at the Daytona 500 zips around the track .its travel the first 80 kilometers in 0.4 hours. the next 114 kilometers take 0.6 . the following 80 kilometers take 0.4 hours to calculate the race car average speed.
A race car at the Daytona 500 zips around the track its travel the first 80 km in 0.4 hours, the next 114km take 0.6, the following 80 km take 0.4, so the average speed is 195.71 km/hr.
How do we calculate the average speed?Average speed of any body will be calculated by dividing the total time to cover the ditance from the total distance covered.
Total distance to cover = 80km + 114km + 80km = 274km
Total time to cover distance = 0.4hr + 0.6hr + 0.4hr = 1.4hr
Average speed of car = 274/1.4 = 195.71 km/hr
So, the average speed of car is 195.71km/hr
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An unknown substance from planet X has a density of 10 g/ml. It occupies a volume of 80 ml. What is the mass of this unknown substance? *
Answer:
The answer is
800 gExplanation:
The mass of a substance when given the density and volume can be found by using the formula
mass = Density × volumeFrom the question
density = 10 g/ml
volume = 80 ml
The mass of the substance is
mass = 10 × 80
We have the final answer as
800 gHope this helps you
Lead (Pb) (average atomic mass 207.19 amu) has three naturally-occurring isotopes, Pb206, Pb207and Pb208 with isotopic masses of 205.98 amu, 206.98 amu and 207.98 amu respectively. If the isotopes Pb207and Pb208 are present in equal amounts, calculate the percent abundance of each isotope of Pb, which are, Pb206, Pb207 and Pb208.
Answer:
pb am 207.19 amu
pb206, pb207and pb208
The density of an element is 11.3 g/cm'. What is its density in kg/mº?
Answer:
11.3 g/cm³ = 11.3x100x100x100/ 1000 = 11300kg/m³
Explanation:
The graph below shows the speed of a downhill
skier during a period of several seconds. Use the
graph to answer Question 13.
16
12
Speed (m/s)
8
0
1
3
3
2
Time (s)
13. Read Graphs What is the skier's acceleration?
Answer:
16
Explanation:
What are the components of the water-based carbon cycle?
Answer:
Carbon gets incorporated into marine organisms as organic matter or structural calcium carbonate.
Explanation:
ur welcome
Carbon gets incorporated into marine organisms as organic matter or structural calcium carbonate.
What is the carbon cycle?The carbon cycle describes how carbon moves between the atmosphere, soils, living creatures, the ocean, and human sources.
Carbon gets incorporated into marine organisms as organic matter or structural calcium carbonate. When organisms die, their dead cells, shells and other parts sink into deep water. Decay releases carbon dioxide into this deep water.
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List all the different ways we can use a model to represent things
What do metaloids share with nonmetals?
Answer:
Most metalloids have some physical properties of metals and some physical properties of nonmetals. They fall between metals and nonmetals in their ability to conduct heat and electricity. They are shiny like metals but brittle like nonmetals.
Explanation:
Identify the reagents
The absolute temperature of a fixed mass of ideal gas is tripled while its volume remains constant. The ratio of the final pressure of the gas to its initial pressure is
Answer:
3 : 1
Explanation:
The following data were obtained from the question:
Initial temperature (T₁) = T
Initial pressure (P₁) = P
Final temperature (T₂) = 3T
Final pressure (P₂) =..?
Since the volume is constant, we shall use the following formula P₁ /T₁ = P₂ /T₂ to obtain the final pressure. This is illustrated below:
P₁ /T₁ = P₂ /T₂
P/T = P₂ /3T
Cross multiply
T × P₂ = P × 3T
Divide both side by T
P₂ = P × 3T /T
P₂ = P × 3
P₂ = 3P
Therefore, the final pressure is tripled.
Finally, we shall determine the ratio of the final pressure to the initial pressure as follow:
Initial pressure (P₁) = P
Final pressure (P₂) = 3P
Final pressure (P₂) : Initial pressure (P₁)
P₂ : P₁ => 3P/P
P₂ : P₁ => 3 : 1
Therefore, the ratio of the final pressure to the initial pressure is 3 : 1
Given sulfur has an electron configuration of 1s22s22p63s23p4, what oxidation numbers would you expect for sulfur? (Hint: Think about how to achieve a full outer shell.)
Explanation:
1s2 2s2 2p6 3s2 3p4
Oxidation number refers to the number of electrons that an atom gains or loses as it forms a chemical bond with another element.
From the electronic configuration above, it is expected that sulphur has oxidation number of 2. This is because the p orbital can hold a maximum of 6 electrons. However, in the electronic configuration it is just holding 4. To complete it, it needs to gain 2 more electrons.
Answer:
+4, +6, –2
Explanation:
which alkene represents the correct starting material phg?
Explanation:
The pH is larger than 7.
The relationship between pH and pOH is
pH + pOH = 14
if something is base, it's pH is greater than 7.
it's pOH is between 0 and 7.
what is the strength of alloys and what is the solubility of alloys please answer this simple question within 12 hours will mark brainliest for sure
Answer:Features very high tensile strength and toughness. Titanium alloys are light in weight, have superior corrosion resistance properties and can withstand extreme temperatures. ... Titanium alloys are heat-treated to increase their strength in terms of fracture toughness, fatigue strength and high temperature strength.35 grams is the sollubility.
Explanation:
In an atom of an element there are a fixed number of electrons. If the total mass of electrons in 1 mole (6.022 x 1023) of atoms of a certain element is 18.65 mg, how many protons must there be in the nucleus of that atom? (mass of electron = 9.109 x 10–28 g).
Answer:
No. of protons = 34
Explanation:
First we need to calculate the number of electrons in one mole of the the element:
No. of electrons per mole = Total Mass of Electrons/Mass of 1 Electron
No. of electrons per mole = (18.65 x 10⁻³ g)/(9.109 x 10⁻²⁸ g)
No. of electrons per mole = 2.04 x 10²⁵ electrons/mol
Now, we calculate the no. of electrons in 1 atom:
No. of electrons per atom = No. of Electrons per mole/No. of atoms per mole
No. of electrons per atom = (2.04 x 10²⁵ electrons/mol)/(6.022 x 10²³ atoms/mol)
No. of electrons per atom = 34 electrons/atom
Since, the no. of protons in a pure element are equal to the number of electrons. Therefore,
No. of protons = 34
In this exercise we have to use the knowledge of atoms to calculate the number of protons, in this way we find:
Protons will be 34
First we need to reckon the number of electrons fashionable individual blemish of the the place where one feels comfortable:
[tex]electrons \ per \ mole = Total\ Mass\ of \ Electrons/Mass\ of\ 1 \ Electron\\ electrons\ per\ mole = (18.65 * 10^{-3} g)/(9.109 * 10^{28} g)\\ electrons \ per \ mole = 2.04 x 10^{25} electrons/mol[/tex]
Now, we plan on the electrons in 1 smallest part of something:
[tex]electrons\ per\ atom = Electrons\ per\ mole/atoms\ per\ mole\\ electrons\ per\ atom = (2.04 * 10^{25} electrons/mol)/(6.022 * 10^{23} atoms/mol)\\ electrons\ per\ atom = 34 electrons/atom [/tex]
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Which lists the waves in order of frequency, from highest to lowest?
O X-rays, gamma rays ultraviolet
O radio waves, visible light, X-rays
O ultraviolet, microwaves, gamma rays
O visible light, infrared, microwaves
Visible light, infrared, microwaves. This is the waves in order of frequency, from highest to lowest. Therefore, the correct option is option D.
What is electromagnetic wave?
One of the various ways that energy moves through space is electromagnetic radiation. Electromagnetic radiation includes the heat from a blazing fire, the sun's light, the X-rays your doctor uses, and the energy used it to cook food inside a microwave. Although though these energies may appear to be very different from each other, they are connected by the fact that they all have characteristics of waves.
The amplitude of a wave is the vertical line between both the tip of the crest and the wave's axis. This is the characteristic linked to the wave's brightness or intensity. The wavelength of a wave is the horizontal separation of two succeeding crests or troughs. Visible light, infrared, microwaves. This is the waves in order of frequency, from highest to lowest.
Therefore, the correct option is option D.
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Which statement best describes chemical properties of matter? Chemical properties, such as density, must be observed when a substance is in its natural state at room temperature and normal atmospheric pressure. Chemical properties, such as reactivity, must be observed when a substance is in its natural state at room temperature and normal atmospheric pressure. Chemical properties, such as combustibility, are generally observed as the identity of a substance changes and one or more new substances form. Chemical properties, such as boiling point, are generally observed as the identity of a substance changes and one or more new substances form.
Answer:
Chemical properties, such as combustibility, are generally observed as the identity of a substance changes and one or more new substances form.
Explanation:
Chemical properties, such as combustibility, are generally observed as the identity of a substance changes and one or more new substances form. Hence, option C is correct.
What are the chemical properties of matter?Chemical properties are properties that can be measured or observed only when matter undergoes a change to become an entirely different kind of matter.
Substances made of wood, such as paper and cardboard, are also flammable.
Chemical properties are properties that can be measured or observed only when matter undergoes a change to become an entirely different kind of matter.
They include reactivity, flammability, and the ability to rust.
Hence, option C is correct.
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what is the volume occupied by 6.022 X 10*23molecules of any gas at STP.
How are the Celsius, Kelvin, and Fahrenheit scales similar? How are they different?
celcius and Fahrenheit are the same at -40 degrees since the scales converge . celcius and Kelvin become Equal at high temperatures as the difference. of 273. 15 between them gets lost in the noise . 0 degree Celsius is Equal to 32degrees Fahrenheit.
List the types of electromagnetic radiation in order of increasing frequency.
Answer:
In order of increasing frequency and decreasing wavelength these are: radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays........... ᕕ( ᐛ )ᕗ
..
If the chemical reaction AB + CD ⟶ AD + BC releases heat, what is true of the stored bond energy of the reactants and products? The bonds do not have energy, the atoms release heat. The bond energy of the reactants is the same as the bond energy of the products. The bond energy of the reactants is lower than the bond energy of the products. The bond energy of the reactants is higher than the bond energy of the products.
Answer:
The correct option is the last option
Explanation:
The chemical reaction provided in the question is a double-displacement reaction which is an exothermic reaction (which is the reason for the release of heat). An example of a double displacement reaction and exothermic reaction is the neutralization reaction illustrated below.
HCl + NaOH ⇒ NaCl + H₂O
From the law of conservation of energy, energy can neither be created nor destroyed, hence the total energy in a given system should ordinarily be the same (in the reactants and products), however when energy is released in a reaction (as in the case with an exothermic reaction), it shows there are more bond energy in the reactants than in the products and it is the excess energy that is been released into the atmosphere.
3-An analysis that determines the relative amounts of analytes in numerical terms
A) Quantitative Analysis
B) Qualitative Analysis
C)Quantitative Synthesis
D) Qualitative Synthesis
Q1-(30 Marks) Choose the correct answer
Answer:
A.
Explanation:
Quantitative analysis.
A scuba tank has pressure of 195 kpa at temperature 10 c the volume of the tank is 350 L how many grams of air ins in the tank?
Answer:
[tex]m=840.88g[/tex]
Explanation:
Hello,
In this case, considering the ideal gas equation as:
[tex]PV=nRT[/tex]
We can first compute the moles of air at the given conditions of 195 kPa (1.92 atm), 10 °C (283K) and 350 L:
[tex]n=\frac{PV}{RT}=\frac{1.92atm*350L}{0.082\frac{atm*L}{mol*K}*283K}\\ \\n=29.03molAir[/tex]
Next, since the molar mass of air is 28.97 g/mol, the mass is computed to be:
[tex]m=29.03mol*\frac{28.97g}{1mol} \\\\m=840.88g[/tex]
Best regards.
(7.31 x 10+4 g) + (3.2300 x 10+3 g) =
Calculator answer
Final answer
You have an atom with a mass number of 100 with 85 neutrons. What is this
element?
Answer:
phosphorus i believe
Explanation:
in order to find the atomic number you minus the mass number from number of neutrons then just look it up in a periodic table
The mass number of the atom is 100 and number of neutrons is 85. Then, number of protons is 15. Then, element with 15 protons and 15 electrons is phosphorous.
What is mass number ?An atom is composed of subatomic particles electrons, protons and neutrons. Protons and neutrons are located inside the nucleus. The mass number of an atom is sum of number of protons and neutrons.
The number of electrons in an atom in its neutral state is called its atomic number. In a neutral atom, the number of electrons and proton are the same.
Give the mass number = 100
no.of neutrons = 85
no.of protons = 100 -85 =15
no.of electron = 15
Thus, atomic number = 15.
The element with atomic number of 15 is phosphorous (P).
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3. The 2 in 1s2 represents the number of
located in that energy level.
Answers:
electrons
protons
Answer:
electrons
Explanation:
In an atom, you can have varying numbers of electrons, depending on if its an ion or not. You can use the orbitals to see the energy level of the atom.
An atom has only one number of protons. The number of protons cannot vary.
A. The measured pH of a 0.100 M HCl solution at 25 degrees Celsius is 1.092. From this information, calculate the activity coefficient of H+.B. The measured pH of a solution of 0.010 HCl and 0.090 KCl at 25 degree Celsius is 2.102. Calculate the activity coefficient of H+ in this solution.C. Why does the pH change in part B relative to that in part A?
Answer:
activity coefficient [tex]\mathbf{\gamma =0.809}[/tex]
activity coefficient [tex]\mathbf{\gamma = 0.791}[/tex]
The change in pH in part A = 0.092
The change in pH in part B = 0.102
Explanation:
From the given information:
pH of HCl solution = 1.092
Activity of the pH solution [a] = [tex]10^{-1.092}[/tex]
[a] = 0.0809 M
Recall that [a] = [tex]\gamma[/tex] × C
where;
[tex]\gamma[/tex] = activity coefficient
C = concentration
Making the activity coefficient the subject of the formula, we have:
[tex]\gamma = \dfrac{[a]}{C}[/tex]
[tex]\gamma = \dfrac{0.0809 \ M}{0.100 \ M}[/tex]
[tex]\mathbf{\gamma =0.809}[/tex]
B.
The pH of a solution of HCl and KCl = 2.102
[a] = [tex]10^{-2.102}[/tex]
[a] = 0.00791 M
activity coefficient [tex]\gamma = \dfrac{0.00791 \ M}{0.01 \ M}[/tex]
[tex]\mathbf{\gamma = 0.791}[/tex]
C. The change in pH in part A = 1.091 - 1.0 = 0.092
The change in pH in part B = 2.102 -2.00 = 0.102
What are the boiling points and freezing points (in oC)of a solution of 50.3 g of I2in 350 g of chloroform? The kb= 3.63 oC/m, the kf= 4.70 oC/m for CHCl3, and the molar mass of I2is 253.8 g/mol. The normal boiling point for CHCl3is 61.2 oC, and the normal freezing point for CHCl3is -63.5 oC.
Answer:
F.p ≈ - 66.16⁰c
B.p ≈ 59.1⁰c
Explanation:
Normal boiling point = 61.2⁰c
Normal freezing point = -63.5⁰c
Kb = 3.63⁰⁰ c/m
Kf = 4.70⁰ c/m
molar mass = 253.8 g/mol
solvent = 350 g = 0.35 kg
calculate The new freezing point and Boiling point
First we have to find the molality = number of moles / solvent in kg
= 0.198 / 0.35 = 0.5657 M
Hence the new freezing point can be calculated as
Normal freezing temp - new freezing temp = Kf * molality
= -63.5 - F.p = 4.7 * 0.5657
F.p = -63.5 - 2.6588 ≈ - 66.16⁰c
Boiling point
Normal boiling point - new boiling point = Kb * molality
= 61.2 - B.p = 3.63 * 0.5657
B.p = 61.2 - 2.0535 ≈ 59.1⁰c