Answer:
1. Neutron number = 43
2. Proton number = 34
3. Electron number = 36
Explanation:
From the question given above, the following data were obtained:
Mass number = 77
Charge of ion = –2
1. Determination of the number of neutron.
Mass number of Se = 77
Atomic number = 34
Neutron number =?
NOTE: Atomic number = proton number
Mass number = Proton + Neutron
77 = 34 + Neutron
Collect like terms
77 – 34 = Neutron
Neutron number = 43
2. Determination of the proton number.
The atomic number of an element is simply defined as the number of protons in the atom of the element. Mathematically,
Atomic number = Proton number
Atomic number of Se = 34
Therefore, the proton number of Se²¯ is 34.
NOTE: The atomic number does not change be it atom, ion or molecule. It remains the same.
3. Determination of electron number.
Charge of ion = –2
Proton number = 34
Electron number =?
Proton – Electron = Charge
34 – Electron = –2
Rearrange
34 + 2 = Electron
36 = Electron
Electron number = 36
There are 43 neutrons, 34 protons, and 36 electrons in the given selenium ion with a (-2) charge.
Explanation:
Given:
A selenium ion with a mass number of 77 and a charge of (-2).
To find:
The number of neutrons, protons, and electrons in selenium ion
Solution:
Charge on the selenium ion = -2
The atomic number of selenium = 34
Number of protons = Atomic number
Number of protons in selenium atom = 34
Number of protons in selenium ion = 34
Number of electrons in selenium atom = 34
Number of electrons in selenium ion= 34+2 = 36
(anion is formed by gaining of electrons that is why adding two electrons )
The mass number of selenium = 77
Mass number = Number of protons + Number of neutrons
77 = 34 + Number of neutrons in selenium
Number of neutrons in selenium ion = 77 - 34 = 43
There are 43 neutrons, 34 protons, and 36 electrons in the given selenium ion with a (-2) charge.
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PCl5 <-> PCl3 + Cl2
PCl5 decomposes into PCl3 and Cl2 according to the equation above. A pure sample of Pcl5 is placed in a rigid, evacuated 1.00 L container. The initial pressure of the PCl5 is 1.00 atm. The temperature is held constant until the PCl5 reaches equilibrium with its decomposition products. The figures below shows the initial and equilibrium conditions of the system.
As the reaction progresses toward equilibrium, the rate of the forward reaction
A) increases until it becomes the same as the reverse reaction rate at equilibrium
B) stays constant before and after equilibrium is reached
C) decreases to become a constant nonzero rate at equilibrium
D) decreases to become zero at equilibrium
Answer:
PCl5 <-> PCl3 + Cl2
PCl5 decomposes into PCl3 and Cl2 according to the equation above. A pure sample of Pcl5 is placed in a rigid, evacuated 1.00 L container. The initial pressure of the PCl5 is 1.00 atm. The temperature is held constant until the PCl5 reaches equilibrium with its decomposition products. The figures below show the initial and equilibrium conditions of the system.
As the reaction progresses toward equilibrium, the rate of the forward reaction
A) increases until it becomes the same as the reverse reaction rate at equilibrium
B) stays constant before and after equilibrium is reached
C) decreases to become a constant nonzero rate at equilibrium
D) decreases to become zero at equilibrium
Explanation:
At equilibrium, both forward and backward reactions take place with constant speed.
The reaction will never cease.
Due to this reason chemical equilibrium is called dynamic in nature.
At equilibrium:
the rate of forward reaction = rate of backward reaction
As the reaction progresses toward equilibrium, the rate of the forward reaction decreases to become a constant nonzero rate at equilibrium.
Answer is option C).
When a system is in a state of chemical equilibrium, neither the reactant concentration nor the product concentration changes over time, nor does the system exhibit any further changes in its attributes. Here the correct option is C.
The system reaches a condition of chemical equilibrium when the rate of the forward reaction equals the rate of the reverse reaction. The system is considered to be in a state of dynamic equilibrium when the concentrations of the reactants and products do not change further as a result of the equal rates of the forward and reverse processes.
Equilibrium is impacted by a number of variables, including temperature, pressure, and the system's concentration. Here at equilibrium the rate of the forward reaction decreases to become a constant nonzero rate at equilibrium.
Thus the correct option is C.
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why elements with more than 20 protons always have a more neutrons than protons?
Answer:
Elements that have atomic numbers from 20 to 83 are heavy elements, therefore the ratio is different. The ratio is 1.5:1, the reason for this difference is because of the repulsive force between protons: the stronger the repulsion force, the more neutrons are needed to stabilize the nuclei.
what are some ways you would expect people and things to be affected by an earthquake that moved the ground that much?
Answer:
Some of the common impacts of earthquakes include structural damage to buildings, fires, damage to bridges and highways, initiation of slope failures, liquefaction, and tsunami.
What does a low number on the pH scale say about a solution?
A. The solution is neutral.
B. The solution is a base.
C. The solution is changing.
D. The solution is an acid.
Answer:
d. the solution is a acid
Answer:D The solution is an acid
Explanation:The lower the pH of a substance the stronger the acidic level.
Jason combines the two intermediate steps shown. 2 equations. First: upper N subscript 2 (g) plus upper O subscript 2 (g) right arrow 2 upper N upper O (g). Second: 2 upper N upper O (g) plus upper O subscript 2 (g) right arrow 2 upper N upper O subscript 2 (g). Which best describes what Jason should do with the oxygen molecules?
Answer:
The molecules of oxygen should be placed as reactants in the equation.
Explanation:
1: N₂ + O₂ → 2NO
2: 2NO + O₂ → 2NO₂
complete reaction:
N₂ + 2O₂ → 2NO₂
In both intermediate equations' oxygen is used as reactant because the end product is the product of the combination of nitrogen and oxygen. So in the complete or overall reaction, oxygen should also be placed as reactant.We can not place oxygen at the side of products neither we can cancel it because, products can only be obtained at the end of the reaction but according to the equations' oxygen is not the end product of the reaction. But the addition into the reaction (Eq. 2) to make the new product.
Also, we can not cancel it because to cancel out molecules of oxygen should be present at the both sides with same amount in the stoichiometric equation.
Hence, in a balanced chemical equation, oxygen should be written as a reactant by using the correct number of moles.
There are on average 43 g of sugar and 355 mL can of soda please calculate the molarity of sugar in the can of soda the molar mass of sugar is 342.2 g/mol
Explanation:
Given :
Amount of solute - sucrose (C12H22O11) = 41 g
Amount of solvent -soda = 355-mL
Molarity of the solution with respect to sucrose= ?
Molarity(M) is a unit of concentration measuring the number of moles of a solute per liter of solution. The SI unit of molarity is mol/L.
Formula to find the molarity of solution :
Molarity =
Amount of solvent is given in mL, let’s convert to L :
1 L = 1000 mL
Therefore, 355 mL in L will be :
= 0.355 L
We have the amount of solute in g, let’s calculate the number of moles first :
Number of moles (n) =
Molar mass of C12H22O11 = 342.29 g/mol.
Therefore, n =
= 0.119 moles.
Silicon is in the same group of the Periodic Table as carbon. The compound
formed between silicon and hydrogen is likely to have the formula
SiHz
SiH
SizH:
SizHs
Please hurry
Answer:
SiH
Explanation:
The symbol for Silicon is Si, and the symbol for Hydrogen is H. There is no need for extra characters in the name.
What is the function of the rough
ER?
A. build proteins
B. modify and repackage proteins
C. contains enzymes
A. build proteins
Explanation:
The endoplasmic reticulum can either be smooth or rough, and in general its function is to produce proteins for the rest of the cell to function. The rough endoplasmic reticulum has on it ribosomes, which are small, round organelles whose function it is to make those proteins
What BEST describes these three molecules?
An aqueous sodium acetate, NaC2H3O2 , solution is made by dissolving 0.395 mol NaC2H3O2 in 0.505 kg of water. Calculate the molality of the solution.
Answer: The molality of [tex]NaC_2H_3O_2[/tex] solution is 0.782 m
Explanation:
Molality is defined as the amount of solute expressed in the number of moles present per kilogram of solvent. The units of molarity are mol/kg. The formula used to calculate molality:
[tex]\text{Molality of solution}=\frac{\text{Moles of solute}}{\text{Mass of solvent (in kg)}}[/tex] .....(1)
Given values:
Moles of [tex]NaC_2H_3O_2[/tex] = 0.395 mol
Mass of solvent (water) = 0.505 kg
Putting values in equation 1, we get:
[tex]\text{Molality of }NaC_2H_3O_2=\frac{0.395mol}{0.505kg}\\\\\text{Molality of }NaC_2H_3O_2=0.782m[/tex]
Hence, the molality of [tex]NaC_2H_3O_2[/tex] solution is 0.782 m
Helppppp plz ASAP DON’T GUESS
Explanation:
A B C D isme koyi ans hain doond lo
How does light demonstrate quantization?
A. The velocity of a light wave has a direction as well as speed.
B. The wavelength of light increases as the frequency decreases.
C. The frequency of light increases as energy increases.
D. The energy in light waves comes in units called photons.
Answer:
D. The energy in light waves comes in units called photons.
Explanation:
its known as quatum theory
Standardization of a Borax solution (Na2B4O7). You are given a 1.044 M solution of H2SO4. It takes 2.63 mL of this H2SO4 to reach the end point. Knowing it takes 1 H2SO4 to neutralize 2 Na2B4O7, what was the concentration of this Borax solution?
The question is incomplete, the complete question is:
Standardization of a Borax solution (Na2B4O7). A student titrates a 20.00 mL sample of an aqueous borax solution with 1.044 M H2SO4. It takes 2.63 mL of acid to reach the equivalence point. Knowing it takes 1 H2SO4 to neutralize 2 Na2B4O7, what was the concentration of this Borax solution?
Answer: The concentration of borax solution is 0.069 M.
Explanation:
To calculate the concentration of borax solution, the formula used is:
[tex]n_1C_1V_1=n_2C_2V_2[/tex] ....(1)
where,
[tex]n_1, C_1\text{ and }V_1[/tex] are the n-factor, concentration and volume of sulfuric acid
[tex]n_2,C_2\text{ and }V_2[/tex] are the n-factor, concentration and volume of borax solution.
We are given:
[tex]n_1=1\\C_1=1.044M\\V_1=2.63mL\\n_2=2\\C_2=?M\\V_2=20mL[/tex]
Putting values in equation 1, we get:
[tex]1\times 1.044\times 2.63=2\times C_2\times 20\\\\C_2=\frac{1\times 1.044\times 2.63}{2\times 20}\\\\C_2=0.069M[/tex]
Hence, the concentration of borax solution is 0.069 M.
Identify which of the following statements about the isotopes of an element is correct.
A. They have the same electron configuration.
B. They have the same mass number.
C. They have the same numbers of protons and neutrons in the nucleus.
D. They have more protons than neutrons.
Answer:
A
Explanation:
because B is wrong as it doesn't have the same mass number. C is wrong as it has different number of neutrons. D is wrong as it has more neutrons than protons.
CHEMISTRY HW... DUE in 2.5 hours! HELP!!!!
Answer:
The final temperature aluminium-water system is 24° C
Explanation:
Heat energy, H = mcθ
Where m is mass of substance, c is specific heat capacity, θ is temperature difference
Using the principle, Heat lost = Heat gained
Let the final temperature of the aluminium-water system be Tfinal
Heat lost by aluminium, H₁ = -m₁c₁(Tfinal - 40)
Heat gained by water, H₂ = m₂c₂(Tfinal -21)
Heat lost by aluminium, H = -[30 × 0.21 × (Tfinal - 40)]
H₁ = -6.3Tfinal + 252
Heat gained by water, H₂ = 50 × 1.0 × (Tfinal - 21)
H₂ = 5Tfinal - 21
Equating H₁ and H₂
-6.3Tfinal + 252 = 5 Tfinal - 21
5Tfinal + 6.3Ffinal = 252 + 21
11.3 Tfinal = 273
Tfinal = 273/11.3
Tfinal = 24° C
Therefore, the final temperature aluminium-water system is 24° C
Given that the acceleration due to gravity is 10N/Kg, calculate the weight of the
Mass (Show all you're working)
Answer:
Weight = 500 Newton
Explanation:
Given the following data;
Acceleration due to gravity = 10N/Kg
Weight can be defined as the force acting on a body or an object as a result of gravity.
Mathematically, the weight of an object is given by the formula;
[tex] Weight = mg [/tex]
Where;
m is the mass of the object.g is the acceleration due to gravity.Note: In order to calculate the weight of a mass, it's required that the mass of an object or body is given.
However, in this particular question it was omitted in error and as such i would assume a value.
Let mass, m = 50 kgSubstituting into the formula, we have;
[tex] Weight = 50 * 10 [/tex]
Weight = 500 Newton
What determines the strength of a dipole dipole force?
Answer:
The more polar the molecules, the stronger the force. The more hydrogen in the molecule, the stronger the force.
Explanation:
I hope this helps and please ask if you need further help!
Which fundamental force(s) can act over very long distances?
A. Gravity and electrostatic force
B. Strong nuclear force and weak nuclear force
C. Gravity only
D. Electrostatic force and strong nuclear force
Answer:
C. Gravity only
Explanation:
What is the predicted change in the boiling point of water when 2.10 g of
barium chloride (BaCl2) is dissolved in 5.50 kg of water?
The addition of any non-volatile solutes will elevate the boiling point of the solution. The change in boiling point of water by the addition of 2.10 of barium chloride is 0.0028 ° C. Hence, option A is correct.
What is boiling point?Boiling point of a substance is the temperature at which it changes from liquid to vapour where the two states are in equilibrium. Boiling point of a substance depends on the bond type, molecular mass and purity of it.
The change or elevation of boiling point of a solution can be determined from its molality m and elevation constant Kb and the Van't Hoff factor i as follows:
ΔT = i Kb m.
Molality of the solution is the no.of moles divided by the mass of solvent in kilogram. Given the mass of barium chloride is 2.10 g and its molar mass is 208.23 g . The no.of moles of solute is 2.10/208.23 g = 0.0100.
Molality of the solution can be calculated as follows:
Molality m = 0.0100 / 5.50 Kg
= 0.0018 mol/kg.
Now, the ΔT s calculated from these values. Provided Kb of water is 0.51 ° C /mol and i = 3.
ΔT = 0.0018 mol/kg × 0.51 × 3
= 0.0028 ° C.
Therefore, water will boil at 100.0028 ° C. Hence, option A is correct.
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List two possible steps where impurities may be gained, which would appear to be an increase in copper
yield (why you may get more than 100% of the copper back at the end). Be specific about the steps and
how they might add impurities.
Answer:
i) During washing
ii) During Measurement
Explanation:
The two possible steps are :
i) During washing : during the washing method the residue may be not completely dried out and this residue ( water) will add up to the final product ( copper yield ) and this kind of error is called human error.
ii) During measurement : If the weighing instrument is faulty there might be addition in value of the final copper yield which will see the final yield value > 100% . this error occurs when the initial value and final value is been weighed
How many mL of 0.013 M potassium hydroxide are required to reach the equivalence point in the titration of 75 mL 0.166 M hydrocyanic acid?
Answer:
957.7mL
Explanation:
Using the formula below;
CaVa = CbVb
Where;
Ca = concentration of acid (M)
Va = volume of acid (mL)
Cb = concentration of base (M)
Vb = volume of base (mL)
According to the information provided in this question:
Ca = 0.166 M
Cb = 0.013 M
Va = 75mL
Vb = ?
Using CaVa = CbVb
0.166 × 75 = 0.013 × Vb
12.45 = 0.013Vb
Vb =12.45/0.013
Vb = 957.7mL
tolong saya jawab yahhh
(i) Liang - liang stoma lebih banyak di bahagian bawah daun berbanding di bahagian atas permukaan daun.
(ii) Struktur X berfungsi mangawal pembukaan dan penutupan liang stoma
A teacher brings in a cup of iced water and asks students to discuss if the system is exothermic or endothermic . Aida states the system is exothermic , while Alexander states the system is endothermic .
Answer:
C
Explanation:
In thermodynamics, a exothermic system looses heat to the surroundings while an endothermic system absorbs heat from the surroundings.
A system is a part the universe marked off by a specified boundary. The contents of the cup constitutes the system in this case.
The region of space outside the system is called the surroundings. Hence everything outside the cup constitutes the surroundings.
Hello Everyone ✌
hw r y'all doin
Pls answer the below questions
What is Malleability
What is ductility
What is Sonorous
Answer:
Malleability describes the property of a metal's ability to be distorted below compression. It is a physical property of metals by which they can be hammered, shaped and rolled into a very thin sheet without rupturing. A malleable fabric could be planate by blow or rolling.
Explanation:
Ductility is the property of a solid, like a metal, to deform under a tensile stress (force). So if you pull on two ends of a metal wire or bar, and it “stretches” you have a ductile substance. Though I must caution that you don't confuse the definition of ductile to mean elastic. They are not synonyms. It is the opposite of brittle. When a ductile item breaks, it is after necking, where the diameter of the wire in question reduces as the length elongated. A brittle, or non-ductile material simple tears apart in a sharp and quick fashion with little to no visible necking taking place.
sonorous: producing sound (as when struck)
Difference between
Atom and molecule
Answer:
Atoms are single neutral particles. Molecules are neutral particles made of two or more atoms bonded together.
Explanation:
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c) Current cannot flow
Reason: Because the switch is not closed.
Answer:
current can't flow
Explanation:
by the way of explanation it is open circuit in which the current flow whereas in closed circuit the current flow.
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it will be too much help for me.
A neutral atom has 37 electrons. How many protons does the
atom have?
a more than 37 protons
bless than 37 protons
C exactly 37 protons
d it is impossible to know without more information
Answer:
It's answer is c) exactly 37 protons
Answer:
C) , Exactly 37 protons.
Explanation:
Remember the electrons have a negative charge, so to make a atom with 37 electrons neutral, you will need the same amount of the opposite type. That means you need 37 protons.
The atom of element has 25 electrons and 30 neutrons write down its atomic number and mass number.
Answer:
Atomic number = 25 protons
Mass number = ( 25 + 30 ) = 55
Some foods undergo sterilization in order to kill bacteria living in and on the
food. What type of radiation is used in sterilization to kill bacteria?
A. Gamma
B. Alpha
C. Beta
D. Fission
Answer:
A: Gamma
Gamma rays have enough energy to kill bacteria
set goals and objectives for a company
Explanation:
Objectives and goals serve as a foundation for successful organizations since they establish the business's objective and aid in the identification of required measures. Goals are broad assertions of what you want to achieve, whereas goals are the precise stages or steps you need to take to get there.
