Answer:
D
Explanation:
If the atom is neutral, the sum of the core and valence electrons is the same as the number of protons, which is the atomic number of the element. So if the sum of the core and valence electrons in a neutral atom equals 25 , that is the number of protons in the atomic nucleus, and the atomic number of the element.
The number of valence electrons plus core electrons is the atomic number.
How is the atomic number related to the variety of electrons?The variety of protons, neutrons, and electrons in an atom may be determined from a set of easy guidelines. The wide variety of protons within the nucleus of the atom is equal to the atomic quantity (Z). The quantity of electrons in an impartial atom is identical to the number of protons.
What's an atomic number associated with?The variety of protons in a nucleus is called the atomic variety and usually equals the number of electrons in orbit approximately that nucleus (in a nonionized atom). For this reason, all atoms which have an equally wide variety of protons and the atomic range are atoms of the equal element.
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Which of the following is represented by the number of significant figures in a quantity? A) estimation B) precision C) accuracy D) scientific notation
Answer: the answer is B estimation
Explanation:
i just took a test
The one that is represented by the number of significant figures in a quantity is scientific notation. The correct option is D.
What is scientific notation?Scientific notation is a method of expressing numbers that are either too large or too small to be written in decimal form.
In the United Kingdom, it is known as scientific form, standard index form, or standard form.
The proper scientific notation format is an x 10b, where an is a number or decimal number with an absolute value greater than or equal to one and less than ten, or 1 |a| 10. b is the power of ten required for scientific notation to be mathematically equivalent to the original number.
Scientific notation is represented by the number of significant figures in a number.
Thus, the correct option is D.
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How are the elements arranged in the modern periodic table?
O A. According to atomic number
B. According to atomic mass
C. According to the number of neutrons
O D. According to the number of electrons
Answer:
A
Explanation:
Indicators change color when an acid and a base are mixed together. The change in color most likely indicates that a chemical change has occured. a physical change has occured. a new acid has been produced. a new base has been produced.
Answer:
a chemical change
Explanation:
a physical change is mostly identified even without indicators i.e candle wax about forming a new acid or base I guess we have to include a ph scale to ascertain since the salt can be acidic but not necessarily an acid
Answer: The answer is A, a chemical change has occurred
Explanation:
I’m just a jenious
What is meant by 1m length
Answer:
The metre is defined as the length of the path travelled by light in a vacuum in 1/299 792 458 of a second.
The lewis representation above depicts a reaction between hydrogen (blue) and a main-group element from group (red). in this representation, each y atom needs 1 electron(s) to complete its octet, and gains these electrons by forming 1 bond(s) with atoms of h . there are 1 unshared electron pair(s) and 1 bonding electron pair(s) in the product molecule. the bonds in the product are .
The question is incomplete, the complete question is;
The Lewis representation above depicts a reaction between hydrogen (blue) and a main-group element from group______ (red).
In this representation, each Y atom needs ______ electron(s) to complete its octet, and gains these electrons by forming______ bond(s) with atoms of H .
There are ______ unshared electron pair(s) and _______bonding electron pair(s) in the product molecule.
The bonds in the product are _________ (Ionic or Covalent)
Answer:
1) 16
2) 2 electrons
3) 2 bonds
4) 2 unshared pairs of electrons
5) 2 bonding pairs of electrons
6) The bonds in the product are covalent
Explanation:
Group sixteen elements have six electrons on their outermost shell. These include two unshared pairs of electrons and two unpaired electrons. These two unpaired electrons can now be covalently bonded to two hydrogen atoms to give H2Y. The compound H2Y has two lone pairs and two bond pairs of electrons.
H2Y can be a general formula for all hydrides of group 16. They are all very similar in structure but gradually differ in physical and chemical properties according to the graduated variation observed down the group.
The molecule has been [tex]\rm H_2Y[/tex], where the two bonds have been formed for the sharing of 2 electrons pair between the H and Y atom.
The Lewis representation above depicts a reaction between hydrogen (blue) and a main-group element from group ______ (red).
The main group element that has the ability to form [tex]\rm H_2Y[/tex] type of structure has been Group 16.
In this representation, each Y atom needs ______ electron(s) to complete its octet, and gains these electrons by forming______ bond(s) with atoms of H .The atom required 2 electrons to complete its octet, and in order to gain two electrons, the atom form 2 bonds with the H, resulting in [tex]\rm H_2Y[/tex].
There are ______ unshared electron pair(s) and _______ bonding electron pair(s) in the product molecule.The atom forms bond with the two H atoms, thus there has been the presence of two unshared electrons pair. The bonding electrons pair are also two in the molecule.
The bonds in the product are _________ (Ionic or Covalent)The bond has been formed with the sharing of the electron pair. Thus it has been a covalent bond.
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A large scuba tank with a volume of 18 L is rated for a pressure of 220 bar. The tank is filled at 20 °C and contains enough air to supply 1860 L of air to a diver at a pressure of 2.37 atm (a depth of 45 feet). Was the tank filled to capacity at 20 °C?
Answer:
Yes, at 20 °C the tank was filled to full capacity
Explanation:
Given;
let initial pressure, P₁ = 2.37 atm
let initial volume, V₁ = 1860 L
let final pressure, P₂ = 220 bar = 217.123 atm
let final volume, V₂ = ?
Subject the air volume (1860 L ) at 2.37 atm to the tank rating (220 bar)
Ideal law is given by;
PV = nRT
At a fixed mole and gas temperature, the equation becomes;
P₁V₁ = P₂V₂
V₂ = (P₁V₁) / P₂
V₂ = (2.37 x 1860) / 217.123
V₂ = 20.3 L
After subjecting the air volume to tank rating, the volume of the air at 220 bar is 20.3 L which is greater than tank volume (18 L).
The extra 2.3 L can be assumed to be compressed gas volume due to the given (lower) temperature.
Thus, at 20 °C the tank was filled to full capacity.
why the filament of bulb has high melting point
Answer:
The filament of a bulb has a high melting point because of the heat generated inside the bulb.
Explanation:
When electricity is concentrating and run through a bulb, it starts to generate heat. Leave it on long enough and it will start to build up a lot of heat. Have you ever tried touching a light bulb when it has been all day? It's scorching to the skin.
Since electricity generates heat, the bulb's filament has to have a high melting point so it doesn't melt, destroy the bulb, and leave you light-less. If the filament has a high melting point, then it is able to withstand heat generated by electricity and provide you light.
What is the electron configuration of chlorine (Cl)?
1s22s22p63s23p3
1s22s22p63s23p5
1s22s22p63s24s23p3
1s22s22p63s23p23d3
Answer:
b) 1s22s22p63s23p5
Explanation:
Answer:
b) 1s22s22p63s23p5
Explanation:
edge 2021
how is impure copper refined by electrolysis
Answer:
By giving electricity to copper compound solution.
Explanation:
Electrolysis is one of the major way of refined copper. The copper containing solution has two electrodes.i) positive electrodes called anode. ii) negative electrodes called cathode. When electricity is pass into the copper containing solution electrolysis process is starts and impure copper is formed in anode and pure copper is formed in cathode.
So, We can get pure copper in cathode through electrolysis.
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If this is helpful for you .Then choose this answer as brainliest answer.
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Consider the half reaction below.
Which statement best describes what is taking place?
Chlorine is losing electrons and being oxidized. Chlorine is losing electrons and being reduced. Chlorine is gaining electrons and being oxidized. Chlorine is gaining electrons and being reduced.
Answer:
balancing of charges of both sides
Answer:
A
Explanation:
A...............................
The figure shows a graph of Allison’s walk to school. She follows the black vectors to get to her school. Which if the following best describes her walk?
Answer:
Allison walks 5 blocks west and 3 blocks south.
Explanation:
Vectors have both magnitude and direction. The attached figure shows the graph of Allison’s walk to school. She follows the black vectors to get to her school.
The first vector on the horizontal axis points towards west and there are 5 blocks. Initially, she walks 5 blocks in west direction.
The second vector points in the negative vertical axis. It means that she walks 3 block in south direction.
Hence, the correct option is (D) i.e. Allison walks 5 blocks west and 3 blocks south.
A scuba diver’s air tank contains oxygen, helium, and nitrogen at a total pressure of 205 atmospheres. The partial pressure of nitrogen is 143 atmospheres, and the partial pressure of helium is 41 atmospheres. What is the partial pressure of oxygen in the tank?
answer is 20
explanation: total Pressure = 205
partial pressure of N = 143
partial pressure of He = 41
total pressure = partial pressure of N + partial pressure of O + partial pressure of He
partial pressure of O = 205 - 185 = 20
Answer:
20
Explanation:
PLEASE HELP ASAP The molecular weight of oxygen gas (O2) is 32 g/mol. What is the mass of a single oxygen atom? 2.66 x 10-23 g 3.13 x 10-1 g 1.06 x 10-23 g 5.31 x 10-23 g
Answer:
5.31×10¯²³ g.
Explanation:
Data obtained from the question include:
Molar weight of O2 = 32 g/mol
Mass of 1 oxygen atom =..?
From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.02×10²³ atoms.
This implies that 1 mole of O2 also contains 6.02×10²³ atoms.
1 mole of O2 = 32 g
The mass of 1 atom of O2 can be obtained as follow:
32 g of O2 contains 6.02×10²³ atoms.
Therefore Xg of O2 will contain 1 atom i.e
Xg of O2 = 32/6.02×10²³
Xg of O2 = 5.31×10¯²³ g
Therefore, the mass of a single oxygen atom is 5.31×10¯²³ g.
The mass of a single oxygen atom is 5.31 x 10⁻²³ grams. Therefore, option D is correct.
The molecular weight of oxygen gas is 32 g/mol. To find the mass of a single oxygen atom, divide the molecular weight by Avogadro's number (6.022 x 10²³ atoms/mol).
Avogadro's number (6.022 x 10²³) represents the number of particles (atoms, molecules, or ions) in one mole of a substance.
To find the mass of a single oxygen atom, divide the molecular weight of oxygen gas by Avogadro's number:
Mass of a single oxygen atom = (32 g/mol) / (6.022 x 10²³ atoms/mol)
Simplifying the expression:
Mass of a single oxygen atom = 5.31 x 10⁻²³ g
Therefore, the mass of a single oxygen atom is 5.31 x 10⁻²³ grams.
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If the pH of a weak acid solution is 2.500 and the solution has a concentration of 0.100M, what is the Ka of the weak acid HA?
Answer:
The Kₐ of the weak acid is 1.033×10⁻⁴
Explanation:
The dissociation of a weak acid in aqueous solution is limited to about 5 to 10%
The acid dissociation reaction is given as follows;
HA (aq) + H₂O (l) → H₃O⁺(aq) + A⁻ (aq)
Given that the pH = 2.5, we have
pH = -log₁₀[H₃O⁺] = 2.5
∴ [H₃O⁺] = 10^(-2.5) = 0.0031623
[tex]K_a = \dfrac{[H_3O^+][A^-]}{[HA]}[/tex]
Kₐ = [H₃O⁺][A⁻]/[HA] = (0.0031623^2)/(0.1 - 0.0031623) = 1.033×10⁻⁴
The acid dissociation constant, Kₐ for weak acid is very low as obtained
What substance does a neutral substance release?
Answer:
Neutral substance is a substance that show no acid or base properties.
Explanation:
Neutral substance is a substances that show no acid or base properties, has an equal number of hydrogen and hydroxyl ions and does not change the color of litmus paper.
Answer:
They release no substance
Explanation:
Since the substance is neutral, nothing will be released from it.
How many electrons can the n = 4 shell hold? 8 16 32 64
Answer:
32Explanation
n = 4
Now,let's find the number of electrons:
[tex]2 {n}^{2} [/tex]
plug the value
[tex] = 2 \times {4}^{2} [/tex]
Evaluate the power
[tex] = 2 \times 16[/tex]
Multiply the numbers
[tex] = 32[/tex]
Hope this helps...
best regards
Electrons are the sub-particles present in atomic shells. The (Principal Quantum Number) n = 4 shell of the atom can hold 32 electrons in it. Thus, option c is correct.
What is Principal Quantum Number?Principal Quantum Number (n) is defined as the distance of the electron from the nucleus and its energy in the atom. It can also be said to know the position of the electron in the energy level along with the orbital size.
The Principle Quantum Number, n = 4 depicts the fourth shell or energy level of the atom that can hold a specific number of electrons in it.
The electrons present in the shell or the energy level are determined by,
2n²
Here, n = 4
Substituting the values above,
= 2 (4)²
= 2 (16)
= 32
Therefore, the n = 4 energy shell can contain 32 electrons.
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Given isotope of nitrogen (N) contains 7 electrons, 7 protons and 8 neutrons. - What is the mass number - What is its atomic number
Answer:
Mass no= 16
and atomic no= 7
Explanation:
mass number is equals to number of protons + number of neutrons .
atomic number is equals to number of protons .
(b) (i)
What is an ion?
(c)
Name two types of ions and state how they are formed
Types of ions:
Answer:
an atom or molecule with a net electric charge due to the loss or gain of one or more electrons
Which type of graph is best used to show how a measured quantity changes over time?
Box and whisker plot
Line graph
Circle graph
Histogram
example of nobel gas
Answer:
helium , krypton,xenon,radon, argon are noble gasses
12. Classify the following as conduction, convection or radiation. a. A steel mug kept near a stove becomes hot after some time. b. The metal handlebars of a bicycle are colder than plastic hand grips. c. Some people get sunburn when they go out in the sun for a long time. d. The paper kept above a candle flame starts burning after some time.
A - convection
B - conduction
C - radiation
D - convection
The cell potential of an electrochemical cell is positive. What does that tell
you about the redox reaction?
A. The reduction part of the reaction occurs at the anode.
B. The oxidation part of the reaction occurs at the cathode.
C. The reaction is spontaneous.
O D. The reaction is nonspontaneous.
Answer:
A. The reduction part of the reaction occurs at the anode
Answer:
A
Explanation:
HELP ME OUT PLZ Today is the deadline
Answer:
Option (1)
Explanation:
When two or more substances are chemically combined in a fixed proportion of mass, substance formed is a compound.
Properties of a compound are different from the properties of the elements from which the compound is formed.
If Magnesium (Mg) is burned in the presence of Oxygen (O₂), Magnesium oxide (MgO) is formed.
Properties of MgO are different from Mg and O₂ because MgO is a COMPOUND.
Option (1) will be the answer.
In an experiment, 125ml of H2 is collected over water at 27C and barometric pressure of 753 torr. the vapor pressure of water at 27C is 26.74 what is the partial pressure of H2?
Answer:
Partial pressure of H₂ = 0.9556 atm
Explanation:
Given:
Barometric pressure = 753 torr
Vapor pressure of water = 26.74 torr
FInd:
Partial pressure of H₂
Computation:
Partial pressure of H₂ = Barometric pressure - Vapor pressure of water
Partial pressure of H₂ = 733 - 26.74
Partial pressure of H₂ = 726.26 torr
1 atm = 760 torr
So,
Partial pressure of H₂ = 726.26/760
Partial pressure of H₂ = 0.9556 atm
sodium react gently with water ture or false
false,
sodium has a vigorous reaction with water.
This can be observed by putting a piece of sodium in water,
it moves swiftly across the surface of water and reacts violently.
A roller coasters velocity at the top of a hill is 21mls. Two seconds later it reaches the bottom of the hill with a velocity of 36mls. What is the acceleration of the roller coasters
Answer:
7.5 m/s²
Explanation:
The following data were obtained from the question:
Initial velocity (u) = 21 m/s
Final velocity (v) = 36 m/s
Time (t) = 2 secs
Acceleration (a) =..?
The acceleration of an object is simply defined as the rate of change of velocity of the object with time. Mathematically, it is represented as:
Acceleration (a) = (final velocity (v) – initial velocity (u)) / time (t)
a = (v – u)/t
With the above formula, we can determine the acceleration of the roller coaster as follow:
a = (v – u)/t
a = (36 – 21)/2
a = 15/2
a = 7.5 m/s²
Therefore, the acceleration of the roller coaster is 7.5 m/s².
What is the solute in the mixture of muddy water
Answer:
A solute is a solid which dissolves in a solvent. Muddy water contains water and soil, soil does not dissolve in water
The mass number of a chromium atom is 52 and it has 24 protons. How many neutrons does this atom have? 24 28 76 80
The number of protons and neutrons together makes the total atomic mass of the element. The atom of chromium has 28 neutrons. Thus, option b is correct.
What is an atomic mass?An atomic mass is the property of an element that defines the number of protons and neutrons of the atom placed in a periodic table. The atomic mass is represented at the lower half of the atomic symbol.
The atomic mass is the sum of the neutrons and the protons that are held together in the nucleus of the atom as a concentrated mass. The atomic number is given as,
Atomic number = number of protons + number of neutrons
Given,
The atomic mass of chromium = 52
Number of protons = 24
Substituting values above:
52 = 24 + number of neutrons
number of neutrons = 52-24
= 28
Therefore, the number of neutrons of a chromium atom is 28.
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Answer: option b, 28
What type of reaction does this equation represent?
2I4O9(s) → 4I2(s) + 9O2(g)
Answer:
2I4O9_4I +9O
Explanation:
Complex compound (
I
4
O
9
) is broken down to form
I
2
and
O
2
Answer:
Decomposition
Explanation:
Because it went from one compound to two elements.
Explain this
When a small piece of glowing sodium is placed inside a gas jar filled with chlorine gas, the sodium continues to burn brightly but when the gas is replaced by argon gas, the glowing sodium becomes extinguished.
Answer:
Because Argon is a inert gas
Explanation:
Inert gases don't take place in any experiments
Answer:
Below.
Explanation:
The sodium reacts strongly with the chlorine to form NaCl and the heat of reaction continues the brightness, whereas it does not react with the inert gas argon and soon cools down.