Answer:
860 J / mol
Explanation:
Enthalpy = Energy / no. of moles
no. of moles = mass / molar mass
Take the atomic mass of H = 1.0,
molar mass of H2 = 1.0 x 2
= 2.0
no. of moles of H2 = 9.00/2
= 4.5 mol
Hence,
Enthalpy = 3870 / 4.5
=860 J / mol
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 .
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.
example of nobel gas
Answer:
helium , krypton,xenon,radon, argon are noble gasses
which one of the following electronic configuration represents the element that forms simple ion with a charge of-3? (a)1s^2,2s^2,2p^6,3s^2,3p^1 (b)1s^2,2s^2,2p^6,3s^2,3p^3 (c)1s^2,2s^2,2p^6,3s^2,3p^6,3d^1,4s^2 (d)1s^2,2s^2,2p^6,3s^2,3p^6
Answer:
(b)
Explanation:
The 3s^2, 3p^6 orbitals form -3 charge.
This is the element phosphorous and an example of a -3 ion is in aluminium phosphide, AlP3.
The electronic configuration which represents the element forming a simple ion having with a charge of -3 is; 1s², 2s², 2p⁶, 3s², 3p³. Option B is correct.
In this electronic configuration, the element has a total of 16 electrons. To form a simple ion with a charge of -3, the element needs to gain three electrons. This is achieved by adding three extra electrons to the existing configuration.
When the element gains three electrons, the electron configuration becomes:
1s², 2s², 2p⁶, 3s², 3p⁶
This configuration represents the stable octet configuration, where the element has a complete outer shell with eight electrons. Since the charge is -3, it means the element has gained three extra electrons to achieve a stable configuration.
Therefore, the correct electronic configuration representing the element that forms a simple ion with a charge of -3 is 1s², 2s², 2p⁶, 3s², 3p³
Hence, B. is the correct option.
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A chemist is identifying an unknown solid substance that appears purple in color. Upon close inspection with a hand lens, she notices tiny grains in the substance. Some of the grains are blue; other grains are red. Based on this information, the substance is most likely a \
The question is incomplete, the complete question is;
A chemist is identifying an unknown solid substance that appears purple in color. Upon close inspection with a hand lens, she notices tiny grains in the substance. Some of the grains are blue; other grains are red. Based on this information, the substance is most likely a
a. Compound
b. Homogeneous Mixture
c. Pure substance
d. solution
e. heterogeneous mixture
Answer:
heterogeneous mixture
Explanation:
A heterogeneous mixture simply means a mixture of two different substances. If two substances are the same, they are expected to have the same colour or appearance.
We were told in the question that the colour of the mixture appeared purple. On close examination, the sample was found to comprise of two different substances of different colours; blue and red.
If there are two substances of different colours present in the sample, it then follows that the sample is a heterogeneous mixture.
Which sequence represents the relationship between temperature and volume as explained by the kinetic-molecular
theory?
higher temperature - more kinetic energy - more space between particles - higher volume
higher temperature-less kinetic energy less space between particles - higher volume
higher temperature → more kinetic energy less space between particles > lower volume
higher temperature-less kinetic energy → more space between particles lower volume
3
and wit
Answer:
A.
Explanation:
Higher temperature - more kinetic energy - more space between particles - higher volume.
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
An atom of an element is shown by the model. A gray circle is surrounded by 4 concentric circles. The innermost circle has gray dots at the north and south positions; the second ring has 8 equally spaced dots, aligning with the inner ring at north and south; the third ring has 14 dots, equally spaced, aligned with the other rings at north and south; the outer ring has dots at north and south. How is this model useful? It shows how electrons are distributed in the shells of an iron atom. It shows how electrons are distributed in the shells of a cobalt atom. It shows how orbitals are distributed in the shells of an iron atom. It shows how orbitals are distributed in the shells of a cobalt atom.
The correct answer is A. It shows how electrons are distributed in the shells of an iron atom.
Explanation:
In the model described, the circles represent the orbitals or shells of the atom, while the dots represent the distribution of electrons (negatively charged sub-particles). Additionally, the description shows the general electronic configuration of this atom is 2, 8, 14, 2, which means in the first orbital there are two electrons, in the second there are eight electrons, in the third, there are fourteenth electrons and in the fifth orbital there are two electrons. This electronic configuration occurs in the atoms of iron. Also, this differs from Cobalt because in cobalt the third orbital has 15 electrons. Thus, the model "shows how electrons are distributed in the shells of an iron atom".
Answer:
a. it shows how electrons are distributed in the shells of an iron atom
Explanation:
edge 2021
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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
Which Group has different numbers of valence electrons?
A. Alkaline earth metals
B. Alkali metals
C. Transition metals
D. Halogens
Answer:
[tex]c. \: transition \: metals[/tex]Transition metals (Group C) have different numbers of valence electrons compared to the other groups mentioned. Therefore option C is correct.
Transition metals (Group 3-12) have varying numbers of valence electrons. This is because their valence electrons are located in more than one energy level or subshell.
The number of valence electrons for transition metals can range from 1 to 12, depending on the specific element within the group. The varying numbers of valence electrons in transition metals contribute to their diverse chemical properties and ability to form multiple oxidation states.
Therefore, transition metals (Group C) have different numbers of valence electrons compared to the other groups mentioned.
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What's the valency of sulphur for Na2SO3
Explanation:
What are the two oxidation states of sulphur in sodium thiosulphate ? In thiosulphate, two sulphurs have oxidation state of -2 and +6. (as per suggestions). Sulphur bonded to three oxygen is considered to have +6 (Sulphur A) and other sulphur has -2 (Sulphur B).
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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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
Smaller particles in an atom are called ____________.
Answer:
[tex]\large \boxed{\sf subatomic \ particles}[/tex]
Explanation:
The smaller particles in an atom are called subatomic particles. Subatomic particles include electrons, protons, and neutrons.
If he wants to model a longitudinal wave that carries more energy, how should he move the end of the spring?
Answer:
they won
Explanation:
distinguish between deliquescence and efflorescence.
Explanation:
Deliquescent substances are solids that absorb moisture from the atmosphere until they dissolve in the absorbed water and form solutions. Efflorescent: Efflorescent substances are solids that can undergo spontaneous loss of water from hydrated salts.
Which of the outer planets is MOST like Earth? How?
Answer:
venus
Explanation:
hope i helped
brainliest pls pls pls
-Zylynn
Answer: I would say that Saturn is most like Earth. Not only does it have moons, like Earth, but the atmosphere is also denser like Earth. It also has windstorms, granite they are much more intense than Earth’s, but they do indeed happen. Saturn also has hydrogen gas; this gas is here on Earth supporting life in our ocean. Therefore, there is a chance that the conditions on Saturn could provide the essentials for there to be life.
The standard reduction potential of a chromium electrode is -0.74 volts when chromium is reduced from chromium (III). The standard potential of the cell where chromium is oxidized and cerium (IV) is reduced to cerium (III) is 2.35 V. For each half reaction how many electrons are transferred
Answer:
three electrons were transferred in the process
Explanation:
The electrode potential of the cathode is
E°cathode= E°cell + E°anode
E°cathode = 2.35V + (-0.74V)
E°cathode= 1.61 V
Let us look at the reduction half equation; the oxidation half equation must be;
Oxidation half equation;
Cr(s) ----> Cr^3+(aq) + 3e
The reduction half equation must now be
Reduction half equation;
3Ce^4+(aq) + 3e ----> 3Ce^3+(aq)
This implies that three electrons were transferred in the process as shown by the balanced half cell reaction equations.
What is the oxidation number of carbon in CO2
Answer: Since oxygen is in group 6 on the periodic table, its valency is
2 −
and hence so is its oxidation number.
But there are 2 oxygen atoms for each carbon atom so the total negative charge due the oxygen is
4 −
But since a molecule must have a net charge of zero in the free form, it implies that the oxidation number of the carbon atom must then be
+ 4
Which statement describes an electron?
Answer:
The statement that describes an electron is "It has a negative charge and is located in orbitals around the nucleus." Electrons are the smallest of the three particles that make up atoms
Explanation:
Electrons are found in shells or orbitals that surround the nucleus of an atom
Electrons are the sub-atomic particles that carry a negative charge over them. In the atom, the electrons are found in the orbitals or the shells around the nucleus. Thus, option D is correct.
What are electrons?
Electrons are the smallest sub-atomic particle that has been known to carry a negative charge and are found in the orbitals of the atom. The charge carried by an electron is 1.602 x 10⁻¹⁹ coulomb and is small than the proton and neutron.
They revolve around the nucleus in their orbits and exhibit the properties of waves and matter. The number of electrons and protons are the same in a neutral atom which makes the atomic number.
Therefore, the electrons have been known to carry a negative charge that revolves in orbit around the nucleus.
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Your question is incomplete, but most probably your full question was, Which statement describes an electron?
It has a positive charge and is located in the nucleus. It has a positive charge and is located in orbitals around the nucleus. It has a negative charge and is located in the nucleus. It has a negative charge and is located in orbitals around the nucleusIndicators 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
Describe how red shifts were used by cosmologists to determine that the universe was expanding. How
is this evidence for the big bang theory?
Explanation:
astronomers have discover that in general the future of a Galaxy is, the more redshift light is this mean that the further away the Galaxy are the faster they are moving this is similar to explosion where the bits moving fastest travel for furthest on the explosion redshift data provides evidence that the universe including space itself is expanding .
Consider a pure crystalline solid that is heated from absolute zero to a temperature above the boiling point of the liquid. Which of the following processes produces the greatest increase in the entropy of the substance?
a) melting the solid
b) heating the liquid
c) heating the gas
d) heating the solid
The question is incomplete, the complete question is;
Consider a pure crystalline solid that is heated from absolute zero to a temperature above the boiling point of the liquid. Which of the following processes produces the greatest increase in the entropy of the substance? A ) melting the solid B ) heating the gas C ) vaporizing the liquid D ) heating the solid E ) heating the liquid
Answer:
vaporizing the liquid
Explanation:
We generally define entropy in chemistry as the degree of disorderliness in a system. The entropy of gases is greater than that of liquids and the entropy of liquids is greater than that of solids. It then logically follows that the degree of entropy in gases is the greatest among all the states of matter while the entropy of solids is the least among all the states of matter since solid particles remain in their mean positions and can only vibrate or sometimes rotate. Liquid particles may translate while gaseous particles move at high velocity with negligible intermolecular forces of attraction between them.
A phase transition from liquid to gaseous state now represents the greatest change in the entropy of the system since gases posses the highest entropy among all the states of matter, hence the answer.
What's the meaning of love?
Answer: Love is when you feel like you can touch the sky when your around that person, when your at your best self or that person and when you put their needs before yours because your needs just don't matter. When you feel like you can't stop thinking about that person or you can stop smiling when you think of them. Its when you feel this warm, safe feeling when your around them. And if you really love them then my answer should be true for you.
Explanation:
because iv'e felt and have been in love before....
Answer:
Love is an intense, deep affection for another person. Love also means to feel this intense affection for someone. Love can also refer to a strong like for something or to like something a lot. Love has many other senses both as a verb and a noun
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...............................
A substance is said to hygroscopic if it
absorbs
(a) Carbon (IV) oxide from the atmosphere
(b) from the surrounding
(c) Moisture from the atmosphere to form
a solution
(d) Moisture from the atmosphere without
dissolving in it.
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:
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.
in terms of bonds what would the molecule C6H12 be classified as
It has a double C=C bond so that means it's unsaturated, but it can also be a cyclic compound with only simple C-C bonds
Alkene
I did the test
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