Answer:
39.02amu
Explanation:
According to this question, there are four (4) isotopes for element X with the following relative abundance:
Isotope 1 = 9.67%, mass no: 38
Isotope 2 = 78.68%, mass no: 39
Isotope 3 = 11.34%, mass no: 40
Isotope 4 = 0.31%, mass no: 41
To find the average atomic mass of element X, we multiply each isotopes' relative abundance by its mass no and find the sum as follows:
We convert each percentage to decimal abundance:
Isotope 1 = 9.67% = 0.0967
Isotope 2 = 78.68% = 0.7868
Isotope 3 = 11.34% = 0.1134
Isotope 4 = 0.31% = 0.0031
(0.0967 × 38) + (0.7868 × 39) + (0.1134 × 40) + (0.0031 × 41)
3.6746 + 30.6852 + 4.536 + 0.1271
Average atomic mass = 39.02amu
In the SI system of units, the mole is one of seven base units. It is frequently used in chemical calculations. However, a mole of something is just a particular quantity of it. It is not a unit of measure in the way that meters, seconds, and kilograms are. Calculations performed with the number of moles of a substance could also be performed with the number of particles of a substance. Based on this information, do you think that the mole should be considered a base unit in the SI system? Explain why or why not.
The international system of units is known as SI and is a metric system. Mostly used as a system of measurement. It is used in science, technology, and nearly in every part of the country. The system includes coherent units known as derived units.
A mole is not a base unit or any property of the units. It can be used for physical and chemical comparison and hence the mole of substance can be performed with the number of particles of the substance.Hence the option B is correct.
Learn more about the frequently used in chemical calculations.
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If 14.7 cm3 of alcohol is present in 70 cm 3 of its aqueous solution, the percentage by volume of alcohol will be?
Answer: The percentage by volume of alcohol will be 21%.
Explanation:
Given: Volume of solute = 14.7 [tex]cm^{3}[/tex]
Volume of solvent = 70 [tex]cm^{3}[/tex]
Formula used to calculate percentage by volume is as follows.
[tex]Percentage volume = \frac{volume of solute}{volume of solvent} \times 100[/tex]
Substitute the values into above formula as follows.
[tex]Percentage volume = \frac{volume of solute}{volume of solvent} \times 100\\= \frac{14.7 cm^{3}}{70 cm^{3}} \times 100\\= 21 percent[/tex]
Thus, we can conclude that the percentage by volume of alcohol will be 21%.
Stoichiometry - Chemistry
Answer:
C
Explanation:
in the option C when we rearrange it then it will he C3H6O2
Answer:
yes its C
Explanation:
correct me if iam wrong
Heat is most closely related to which kind of energy?
O nuclear
electrical
thermal
chemical
Answer:
C thermal
Explanation:
Hematite is a naturally occurring mineral and a common form of iron ore. The following statements describe physical and chemical changes occurring to hematite. Which statement describes a chemical change?
When the hematite particles rearrange to form a new substance", this statement describes chemical change.
What is chemical change ?A chemical change is a change of materials into another, new materials with different properties and one or more than one new substances are formed.
As a chemical changes is usually a change where a substance undergoes a chemical change and forms a new substance; which cannot be easily reversed into reactants by any simple physical methods.
In this example the hematite ore forms a new substance by an irreversible chemical change.
Hence, "The hematite particles rearrange to form a new substance", this statement describes chemical change.
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.
Unlike a theory, a scientific law describes an observed pattern without attempting to _____ it.
explain
prove
test
verify
HELPPPPPPPP i accidentally pressed on c
Answer:
a
Explanation:
I'm not completely sure tho veary sorry if it's wrong
Answer:
the answer is C
Explanation:
as the yeast feeds on sugar and yields the ATP per glucose molecule and Carbon dioxide
Calculate the volume (in L) occupied by 3.40 g of NH3 at STP. (STP: 0 degree Celsius and 1 atmosphere of pressure).
Answer:
Calculate the volume (in L) occupied by 3.40 g of NH3 at STP. (STP: 0 degree Celsius and 1 atmosphere of pressure).
Explanation:
To get the volume of ammonia gas at STP, calculate the number of moles of [tex]NH_3[/tex] in the given amount.
Number of moles of [tex]NH_3[/tex] gas is:
[tex]number of moles of NH_3 gas&=\frac{given mass of the gas}{its molecular mass} \\ &=\frac{3.40g}{17.0g/mol} \\&=0.2 mol.[/tex]
Since,
1 mol of any gas at STP occupies ------- 22.4 L of volume.
then,
0.2 mol of [tex]NH_3[/tex] occupies how much volume?
[tex]=>0.2 mol x \frac{22.4 L}{ 1.0 mol} \\=4.48 L[/tex]
Hence, the volume occupied by 3.40 g of ammonia at STP is --- 4.48 L.
Question 2: Heat (5 points)
A. Describe the following heat equations, and identify the indicated variables.
i. Q = mcΔT; identify c. (1 point)
ii. Q = mLvapor; identify Lvapor. (1 point)
iii. Q = mLfusion; identify Lfusion. (1 point)
Answer:
(i) specific heat
(ii) latent heat of vaporization
(iii) latent heat of fusion
Explanation:
i. Q = mcΔT; identify c.
Here, Q is heat, m is the mass, c is the specific heat and ΔT is the change in temperature.
The amount of heat required to raise the temperature of substance of mass 1 kg by 1 degree C is known as the specific heat.
ii. Q = mLvapor; identify Lvapor
Here, Q is the heat, m is the mass and L is the latent heat of vaporization.
The amount of heat required to convert the 1 kg liquid into 1 kg vapor at constant temperature.
iii. Q = mLfusion; identify Lfusion
Here, Q is the heat, m is the mass and L is the latent heat of fusion.
Here, Q is the heat, m is the mass and L is the latent heat of vaporization.
The amount of heat required to convert the 1 kg solid into 1 kg liquid at constant temperature.
(i) c is the molar heat capacity of the substance.
(ii) Lvapor is the latent heat of evaporation of the substance
(iii) Lfusion is the latent heat of fusion of the substance
All the 3 equations fall under Calorimetry.
In all the equation Q is the amount of heat required.
(i) First equation represents the amount of heat required to raise the temperature of a substance of mass m.
Q = mcΔT
here c is the molar heat capacity of the substance and ΔT is the chnage in temperature.
(ii) Second equation represents the amount of heat required to convert a substance of mass m from liquid phase to vapour phase.
Q = mLvapor
here Lvapor is the latent heat of evaporation of the substance
during evaporation no change in temperature occurs.
(iii) Third equation represents the amount of heat required to convert a substance of mass m from solid phase to liquid phase.
Q = mLfusion
here Lfusion is the latent heat of fusion or melting of the substance
during fusion no change in temperature occurs.
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What would you need to do to calculate the molality of 10 mol of NaCl in 200
mol of water?
A. Convert the 10 mol of NaCl to kilograms of NaCl.
O B. Convert the 200 mol of water to liters of water.
C. Convert the 200 mol of water to kilograms of water.
D. Convert the 10 mol of NaCl to grams of NaCl.
 Help ASAP only right answers only no spam don’t answer if you don’t know
i know the answer is a theory
Which of the following statements regarding the movement of electrons during cellular respiration is true?
A. Electrons tend to move away from O2.
B. O2 is reduced when it accepts electrons and forms water.
C. The electrons release large amounts of energy each time they are transferred from one molecule to another.
D. O2 is eventually oxidized by the electrons to form water.
Answer:
B. O2 is reduced when it accepts electrons and forms water.
Explanation:
During cellular respiration water is formed when oxygen receives electrons and picks up protons at the conclusion of the electron transport chain. The electron transport chain will stop functioning if there isn't enough oxygen to receive electrons (for example, because a person isn't breathing in enough oxygen), and ATP will no longer be created by chemiosmosis. Cells can't carry out the reactions they need to function if they don't even have enough ATP, and they may perish after a long period of time.
every action produces an equal and opposite -- ---------- when one object exterts a force on another object,the second object pushes back with the same amount of---------
someone knows the answer
HELP ASAP!! PLEASE !!
Answer:
8,3, 7,7
Explanation:
If charge on only one object is tripled, determine the new force between them:
Answer:
+3·F
Explanation:
The number of objects in the given system = 2 objects
The charge on each object are; q₁ = -Q, q₂ = -Q
The force acting between the objects = +F
The distance between the objects = 2·d
The formula for the force acting between two charged particles is given as follows;
[tex]F=K \times \dfrac{q_{1} \times q_{2}}{r^{2}}[/tex]
Therefore, we get;
[tex]F=K \times \dfrac{-Q \times -Q}{(2\cdot d)^{2}} = K \times \dfrac{Q^2}{4 \cdot d^2}[/tex]
By tripling the charge, q₁, on the first object, we get;
q₂ = 3 × (-Q)
[tex]F_2=K \times \dfrac{-3 \cdot Q \times -Q}{(2\cdot d)^{2}} = K \times \dfrac{3 \cdot Q^2}{4 \cdot d^2} = 3 \times +F = +3\cdot F[/tex]
Therefore, the new force between them, F₂ = +3·F
Place the steps of the action potential in order.
- a brief reversal of membrane potential that travels along the axon
- mechanism that restores the resting membrane voltage and intracellular ionic concentrations
- reversal of the resting potential due to an influx of sodium ions
- period during which potassium ions are diffusing out of the neuron because of a change in membrane permeability
Answer:
-Reversal of the resting potential due to influx of sodium ions
-Mechanism that restores the resting membrane voltage and intracellular ionic concentrations
-Period during which potassium ions are diffusing out of the neuron because of a change in membrane permeability
-A brief reversal of membrane potential that travels along the axon
Explanation:
An action potential is a situation where the membrane potential is briefly reversed from -70mV to +30 mV
There are three steps of the moving action potential, including;
1) The depolarization step, where the membrane resting potential is reversed by the rush of sodium ions into a neuron
2) The repolarization, due to the closing of the voltage-gated sodium channels and the opening of the potassium channels, which is a mechanism that restores the membrane's resting voltage and the ionic concentration in the cell
3) Hyperpolarization, where due to some open potassium channels, there is an increased potassium permeability, and excessive efflux of potassium ions take place, which results in a dip in the membrane potential
4) The above three phases describe the phase of the action potential which is the brief reversal of membrane potential that travels along the axon
5.34x10 to the 27th power molecules of sulfur hexafluoride to moles of sulfur hexafluoride
Answer:
8.87 × 10³ moles.
Explanation:
To convert number of molecules of sulfur hexafluoride (SF6) to moles (n), we divide by Avogadro's number (6.02 × 10²³)
That is; n = N ÷ nA
According to the question, 5.34 x 10^27 molecules of SF6 was given in this question. Hence, the number of moles it contains is given as:
n = 5.34 x 10^27 ÷ 6.02 × 10²³
n = 5.34/6.02 × 10^ (27-23)
n = 0.887 × 10⁴
n = 8.87 × 10³ moles.
As a pure element the oxidation number of zinc is ________, but in compounds such as ZnCO3 its oxidation number is ________. Group of answer choices
Answer:
0, +2
Explanation:
As a pure element, any element or simple compound has an oxidation number of 0. This makes it a lot easier, and can be applied for almost any element or compound that uses one atom, like F2, O3, Zn, Fe, etc. However, in compounds, Zinc's oxidation number tends to be +2, and this is just a rule that I memorized when I learned this topic. Please let me know if you still need help and I hope you understood!
As a pure element, the oxidation number of zinc is zero, but in compounds such as [tex]ZnCO_3\\[/tex] its oxidation number is +2.
What is the oxidation number?Oxidation number also called oxidation state, is the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom.
As a pure element, any element or simple compound has an oxidation number of 0. This makes it a lot easier and can be applied for almost any element or compound that uses one atom, like [tex]F_2[/tex], [tex]O_3[/tex], Zn, Fe, etc.
However, in compounds, Zinc's oxidation number tends to be +2.
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Un medicamento corresponde a una disolución de "nafazolina" (sustancia activa) en agua purificada, en una concentración de 12% V/V. - EXPLICA cuánto soluto hay por cada 100mL del medicamento.
Answer:
12 mL
Explanation:
Según la pregunta;
V / V% concentración del fármaco = 12%
volumen de la solución = 100 ml
De;
V / V% = volumen de fármaco / volumen de solución
volumen de fármaco = V / V% × volumen de solución
volumen de fármaco = 12/100 × 100
= 12 mL
explain why the boiling point of aluminum is higher than sodium
Explanation:
this is the reason why aluminium's boiling point is higher than that of sodium. sodium forms Na+ ions, therefore 1 electron is lost from each sodium atom, whereas aluminium forms Al3+ ions, so 3 electrons are lost for each Aluminum atom. The number of delocalised electrons therefore increases from sodium to aluminium, and charge density of the ions increases as the ionic charge increases and size decreases.
You are a chemist working in your laboratory. In your storage closet you have a
cabinet that holds only samples of pure elements, no compounds. While looking for a
sample of lithium (LI), you notice that the label on one bottle has worn off. The room is
at normal temperature. The contents of the bottle are liquid and do not look metallic.
What element should you relabel the bottle as?
A.Helium
B.Bromine
C.Arsenic
D.Chlorine
thank you so much for putting all the answers in there
Answer:
[tex]\huge\color{cyan}{\colorbox{magenta}{Answer}}[/tex]
thank you
Help me guys ☹️please
Answer:
Coriolis Effect
Explanation:
The Coriolis Effect is caused by Earths rotation. We can not only see this affecting how winds move, but also where storms form and the movement of oceans currents.
How many cm3 in a L?
Glycerin, , is a nonvolatile liquid. What is the vapor pressure of a solution made by adding glycerin to at
Complete question is;
Glycerin, C3H8O3, is a nonvolatile liquid. What is the vapor pressure of a solution made by adding 164 g glycerin to 338 mL H2O at 39.8°C?
The vapor pressure of pure water at 39.8°C is 54.74 torr and its density is 0.0992 g/cm³
Answer:
28 torr
Explanation:
Let's first find the number of moles of water in 338 mL.
Molar mass of water = 18 g/mole
Formula for number of moles = mass/molar mass.
Mass = density × volume = 0.0992 × 338 = 33.5296 g
Thus;
Number of moles = 33.5296/18 = 1.863 moles.
Let's use the same procedure to find the Number of moles of glycerine.
Molar mass of glycerine from online values = 92.1 g/mol
Thus;
n_glycerine = (mass)/92.1
We have mass and density as 164 g and 0.0992 g/cm³ respectively.
n_glycerine = 164/92.1
n_glycerine = 1.78
Total moles of solution = 1.863 + 1.78 = 3.643 moles
We are told that The vapor pressure of pure water at 39.8°C is 54.74 torr
Thus, since water dominates, then vapour pressure of solution = (1.863/3.643) × 54.74 ≈ 28 torr
The mass of a boy is 60 kg. Calculate his weight if the value of g is 9.8 ms2
Answer:
Weight = mass × gravitational
Weight = 60 kg × 9.8 ms²
= 588 N
Explanation:
hope it helps
Weight of the boy = Mass of the boy × g
= 60 × 9.8
= 588kgm/s²
= 588N
How many ATOMS of boron are present in 3.61 grams of boron trifluoride ?
Answer:
To determine the number of atoms of Boron that are present within 3.61 grams of Boron Trifluoride, it would be best to convert the grams to moles of the compound and then after that use the Avogadro's number to determine the number of molecules and then use the 1 to 3 ratio to determine the total number of Boron atoms.
1) The percentage of oxygen in dry air is _______
A. 0.1
B. 1.0
C. 21
D. 79
2) The composition of the Earth’s earliest atmosphere was different to that of the present atmosphere. Which of these gases was present in large amounts in the Earth’s earliest atmosphere?
A. Oxygen
B. Carbon dioxide
C. Ammonia
D. Nitrogen
Answer:
1) The percentage of oxygen in dry air is _______
C. 21
2) The composition of the Earth’s earliest atmosphere was different to that of the present atmosphere. Which of these gases was present in large amounts in the Earth’s earliest atmosphere?
B. CARBON DIOXIDE
Hope it helps
have a nice day
Answer: The percentage of oxygen in dry air is . 21
Explanation: Ammonia gases was present in large amounts in the easth7s earliest atmosphere
Hope it will help you
How would an increased level of acetyl-CoA be expected to affect the pyruvate dehydrogenase reaction
Answer:
The pyruvate dehydrogenase kinase enzyme activity would increase, resulting in an inhibition of pyruvate dehydrogenase activity. ... An in vitro study shows that isocitrate dehydrogenase is activated in the citrate cycle.
Explanation:
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19. place moth balls in the closet and observe after several days.
20. whenever wax or a candle burns it turns from solid to liquid but again at room temperature it turns to solid
21. evaporation, condensation, precipitation
22. it produces new substances
23. vinegar Bubbles when baking soda is added
24. steam