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Calculate the atomic mass of the unknown element X described below.
Please help
Answer:
286
Explanation:
Add atomic mass of all the Isotopes,
Outcome = 825
divide it by number of isotopes which is 4 because there are 4 isotopes
Atomic mass of x = [tex]\frac{825}{4}[/tex]
Atomic mass of x is 286
The atomic mass of the unknown element X is 206 amu. Thus option B is correct.
What is atomic mass?Atomic mass is defined as the relative mass of the element's atom in comparison to the mass of an atom of the C12 isotope.
In an example, the general atomic mass is the average of the atomic masses of a large number of different isotopes.
First we added atomic mass of each isotopes
= 204 + 206 + 207 + 208 = 824
Now to calculate the atomic mass of element X we divide it by 4 as there is four isotopes
So, atomic mass = 824 / 4
= 206 amu
Thus, the atomic mass of the unknown element X is 206 amu. Thus option B is correct.
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What is the mass number of Carbon–12, which has 6 protons and 6 neutrons?
Answer:
It has the atomic mass of 12.
For the combustion of methane, CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l) △H = -213
kcal/mol
How many kilocalories of energy are released from 5.0 mol of methane?
How many moles of methane are needed to give 100. kcal heat?
Answer:
1.-213(kcal/mol)*5mol=1065kcal
2.100/213 mol
a. The energy released from 5.0 mol of methane is -1065 kcal/mol.
b. The number of moles of methane needed to give 100. kcal heat is 0.4694 moles.
What is combustion?Combustion is a chemical process in which the element reacts with oxygen to produce heat and light. Burning of wood.
The equation of combustion of methane:
CH₄ (g) + 2O₂(g) ------> CO₂ (g) + 2H₂O (l)
a) Enthalpy of the reaction is H = -213 Kcal/mol
This means 213 Kcal heat is released in the burning of one mole of CH4
H reaction = [ H products ] - [ H reactants ]
Hr = [ H(CO₂)g + 2H(H₂O)l ] - [ H(CH₄)g ] = -213 kcal/mol
For 5 moles of methane:
5CH₄(g) + 10O₂(g) -----> 5CO₂(g) + 10H₂O(l)
therefore, new Hr = 5 x -213 = -1065 kcal/mol
H reaction = -1065 kcal/mol
b) 213 kcal is released per mole of Methane
then, to release 100 kcal we need, 100 / (213) = 0.4694 moles
Thus, the energy released is -1065 kcal/mol, and the number of moles is 0.4694 moles.
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I need help with these 2 problems ASAP please.
This is not chemistry but i could not find science
(THIS QUESTION IS FOR SCIENCE)
Answer:
1. is sickle-cell anemia and 2. is phenyketonuria
Explanation:
Electron spin around the nucleus in specific paths called?
Answer:
Electron cloud
Explanation:
I will mark brainliest as soon as there are two answers! Please be quick, I'm timed
A mineral forms in water heated by magma inside Earth.
Which statement best describes this mineral?
The mineral formed through evaporation.
The mineral crystallized from molten material.
The mineral formed when a hot water solution cooled.
The mineral likely has all the same properties as the surrounding rock.
Answer: i would do the mineral formed when a hot water solution cooled because you said that a mineral forms in water heated by magma inside Earth.
Explanation:
The answer would be C
Explanation:
When magma cools down it will change into a rock type so the answer would be C.
What of the following is made out of atoms? (HINT: vocabulary word "atom" or "matter") * 1 Air
2 Light
3 Energy
4 Sound
which type of matter is represented by the particle diagram
Answer:
a compound
Explanation:
Which of the following representations shows the correct placement of trophic levels?
Secondary Consumers
Primary Consumers
Producers
Help pls:)?
If the low power objective has 10X printed on it, what would be the total magnification when looking through the microscope?
Answer:
The magnification of the microscope is equal to the magnification of the ocular lens times the magnification of the objective lens. Since the objective lens has 10x printed on them at "low power". The total magnification would be 10 times 10.
Explanation:
i hope this helps C:
Ok here is the next one
I’m counting on you
Thanks.
food moves through the mouth by muscle movement
A type of substance containing atoms of two or more different elements that are chemically bonded together is referred to as a
Answer:
Compound
Explanation:
The lowest energy state of an atom is its
A. Highest-occupied energy level.
B. Principle quantum number.
C. Electron configuration.
D. Ground state.
Answer:
Principle quantum number.
Explanation:
The graph shows the average monthly rainfall for a
forested area.
In which month is a high alert for fire danger most
likely?
A. April
B. August
C. May
D. October
Answer:
The Answer would be A. April
Explanation:
Least amount of rainfall out of all the months we have to choose from.
g If the pressure of each gas is increased at constant temperature until condensation occurs, which gas will condense at the lowest pressure
The question is incomplete; the complete question is;
If the pressure of each gas is increased at constant temperature until condensation occurs, which gas will condense at the lowest pressure?
A) Octane
B) Ethane
C) Butane
D) All the gases will condense at the same pressure
Answer:
Octane
Explanation:
If we study the table closely we will realize that octane has the greatest molecular mass among all the gases shown.
The greater the molecular mass, the lower the pressure required for the condensation of the gas. Hence, the lowest pressure is required for the condensation of octane at constant temperature.
What is the first step when using a microscope?
A. Place the microscope slide on the stage
B. Plug the microscope in and turn it on
C. Switch to the low power objective lens
D. Secure the slide to the stage clips
Answer:
I think the answer is B :)
Answer:
the first step is B
Explanation: I'm on this lesson
II. Pure magnesium metal is often found as ribbons and can easily burn in the presence of oxygen. When 3.86 g of magnesium ribbon burns with 155ml of oxygen at 1.0 atm and 275 K , a bright, white light and a white, powdery product is formed, magnesium oxide. How many grams of excess reactant remain?
Answer:
[tex]Excess=3.53g[/tex]
Explanation:
Hello,
In this case, the undergoing chemical reaction is:
[tex]2Mg(s)+O_2(g) \rightarrow 2MgO(s)[/tex]
Next, we identify the limiting reactant by computing the moles of magnesium oxide yielded by 3.86 g of magnesium and 155 mL of oxygen at the given conditions via their 2:1:2 mole ratios and the ideal gas equation:
[tex]n_{MnO}^{by \ Mg}=3.86gMg*\frac{1molMg}{24.3gMg}*\frac{2molMgO}{2molMg} =0.159molMgO\\\\n_{MnO}^{by \ O_2}=\frac{1atm*0.155L}{0.082\frac{atm*L}{molO_2*K}*275K} *\frac{2mol MgO}{1molO_2} =0.0137molMgO[/tex]
It means that the limiting reactant is the oxygen as it yields the smallest amount of magnesium oxide. Next, we compute the mass of magnesium consumed the oxygen only:
[tex]m_{Mg}^{consumed}=0.0137molMgO*\frac{2molMg}{2molMgO} *\frac{24.3gMg}{1molMg} =0.334gMg[/tex]
Thus, the mass in excess is:
[tex]Excess=3.86g-0.334g\\\\Excess=3.53g[/tex]
Regards!
How many electrons does 2Na+1 have
Answer:
So... for the element of SODIUM, you already know that the atomic number tells you the number of electrons. That means there are 11 electrons in a sodium atom. Looking at the picture, you can see there are two electrons in shell one, eight in shell two, and only one in shell three.
Explanation:
brainliest pleaseeee <3
Answer:
so there would be 2 electrons because
Explanation:
sodium has 11 electrons but if you look at the shels it onl has one electron (from the image im looking at) and the other shell only have one so theres 2 electrons
Which changes MUST happen for elements to become a compound
Answer:
Chemical changes in compounds happen when chemical bonds are created or destroyed. Then the molecular structure changes; new molecules form and a new substance is created. Often heat is used to begin a chemical change, as when baking a cake. Another example of a chemical reaction is the rusting of a metal trash can.
Hope this helps you Do mark as brainliest ✌️An element is constituted of only atoms and no other entities are present in it. Whereas a chemical compound is a substance made up of various identical molecules of the same or different atoms.
The atoms of the same or different species bond together to form a compound.
Chemical bonding is present among them that cannot be simply separated.The compounds can have ionic, covalent and hydrogen bonds present in them.When the new atoms combine the structure changes of the new molecule formed.To learn more about compounds and atoms follow the link:
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why does adding salt to ice make it melt faster
Which element has more metallic properties?
Lead or Germanium
lead has more metallic properties
is a granite a mineral or a rock
Answer:
Rock
Step-by-step explanation:
It's an igneous rock
I hope this helps!
Which of the following is the metric system based on?
Which carboxylic acid can be combined with an alcohol to form the ester shown below?
Answer:
CH₃CH₂CH₂COOH.
Explanation:
To know which option is correct, let us hydrolysed the given ester. This is illustrated in the attached photo.
Hydrolysis of ester involves breaking the ester bond by a water molecule to produce the corresponding alcohol and carboxylic acid.
From the reaction given in the attached photo, we can see that the carboxylic acid needed to produce the desired ester is butanoic acid, CH₃CH₂CH₂COOH.
In two to three sentences, explain the trend for atomic size. Why does this trend occur?
Answer:
The number of energy levels increases as you move down a group as the number of electrons increases. Each subsequent energy level is further from the nucleus than the last. Therefore, the atomic radius increases as the group and energy levels increase. 2) As you move across a period, atomic radius decreases.
Explanation:
Kinetic and potential energy are two types of energy that relate too
Answer:
Option B. A tractor–trailer traveling at 80 kph.
Explanation:
Kinetic energy can be defined as the energy possessed by a body in motion. Mathematically, it is expressed as:
K.E = ½mv²
Where:
K.E is the kinetic energy.
m is the mass of the object.
v is the velocity of the object.
From the equation, K.E = ½mv²,
We can say that the kinetic energy (K.E), is directly proportional to both the mass (m) and square of the velocity (v). This implies that the greater the mass of an object, the greater the kinetic energy and the smaller the mass, the smaller the kinetic energy.
Now, considering the options given in question above, it is evident that the tractor–trailer has a greater mass than the car, cheetah and motor cycle. Hence, the tractor–trailer will have a greater kinetic energy even though they are traveling with the same velocity.
Why is it important o differentiate between human and animal blood from a crime scene? A) To determine whether an animal might have been injured. B) In order to accurately identify the source of any blood. In order to thoroughly and accurately recreate the crime scene. D To determine the possible source of any trace evidence such as hair or bite marks
Answer:
B) In order to accurately identify the source of any blood. In order to thoroughly and accurately recreate the crime scene.
Chemical properties can be observed without changing the substance
Answer:
chemical properties can only be measured only by changing a substance chemical identity
Explanation:
apex
In which phase transition do molecules move directly from a state involving vibration of particles in a fixed position to a state involving random movement of high-speed particles?
evaporation
sublimation
freezing
deposition
would be your answer because it releases other cells out and causes the needy of cells to evaporate and sink.
sublimation is the phase transition do molecules move directly from a state involving vibration of particles in a fixed position to a state involving random movement of high-speed particles.
What is Sublimation?In the process of printing sublimation shirts, an image is first printed on a special sheet of paper before being transferred to a different material, typically polyester or a polyester blend. After that, heat is applied to the ink until it fuses with the fabric.
Sublimation shirt printing is more expensive than other procedures, but it produces shirts that stay longer and don't peel or crack over time.
he primary distinction between sublimation and heat transfer is that during sublimation, just the ink transfers to the substrate. A transfer layer is frequently also transferred to the material during the heat transfer procedure.
Therefore, sublimation is the phase transition do molecules move directly from a state involving vibration of particles in a fixed position to a state involving random movement of high-speed particles.
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True or false: An oxidation number is not the same as an actual charge on an ion. True false question. True False
Answer:
True
Explanation:
They are actually the same
The answer is False.
The oxidation number is the number of electrons removed or added to an element or compound. This is also equal to the charge on the ion.
For example, if Sodium atom loses one electron, it becomes oxidized to the + 1 state.
Na → Na⁺ + e⁻.
So, the oxidation number of Sodium is the charge on the Sodium ion which is + 1.
So, the oxidation number is equal to the charge on the ion.
So, the answer is False.
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