Select the correct answer.
A sample taken from a layer of mica in a canyon has 2.10 grams of potassium-40. A test reveals it to be 2.6 billion years old. How much
potassium-40 was in the sample originally if the half-life of potassium-40 is 1.3 billion years?
O A.
4.20 g
O B.
8.40 g
O C.
12.6 g
• D.
16.8 g
O E.
25.2 g
Answer:
8.36 g
Explanation:
From;
0.693/t1/2 = 2.303/t log (No/N)
t1/2 = half life of potassium-40
t = age of the sample
No= initial amount of the sample
N= amount of the sample at time t
Substituting values;
0.693/1.3 × 10^9 = 2.303/2.6 × 10^9 log (No/2.10)
5.33 × 10^-10 = 8.86 × 10^-10 log (No/2.10)
5.33 × 10^-10/8.86 × 10^-10 = log (No/2.10)
0.6 = log (No/2.10)
Antilog (0.6) = (No/2.10)
No = 2.10 × Antilog (0.6)
No= 8.36 g
A solution of ammonia NH3(aq) is at equilibrium. How would the equilibrium
change if NH4+ were added to the solution?
Answer: The equilibrium will shift in the direction of [tex]NH_3[/tex]
Explanation:
The chemical equation for the aqueous solution of ammonia follows:
[tex]NH_3+H_2O\rightleftharpoons NH_4^++OH^-[/tex]
According to Le-chtelier's principle:
If there is any change in the variables of the reaction, then the equilibrium will shift in that direction of equilibrium to minimize the effect.
If we add more amount of [tex]NH_4^+[/tex] to the solution, more of the products will be present. But according to Le-chtelier's principle, to minimize this effect, the equilibrium will shift in the backward direction that in the direction of [tex]NH_3[/tex]
Hence, the equilibrium will shift in the direction of [tex]NH_3[/tex]
If no loss or gain of electrons occur by mixing of two atoms, we say that they may be attached to each
other due to
A proton attraction
B neutron attraction
C sharing of electrons
D opposite charges
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Answer:
The correct option is option C
Explanation:
Loss or gain of electron(s) occurs in a type of attraction known as electrovalent or ionic attraction. In this type, there is transfer (or loss) of electron(s) from a metal atom to become positively charged while a nonmetal accepts (or gains) this electron to become negatively charged.
When this does not happen, two metal atoms can become attached by sharing the same electrons through a form of attraction known as covalent bonding. Here, the two atoms share electrons (known as shared pair) together to achieve there octet configuration on the outermost shell.
Help please I’ll give you brainless
Answer:
Step 9
Explanation:
The reason i selected step 9, is if you take a look at the picture hes setting up a funnel,With filter paper and if you take a look at number ''9'' questions it says set up a funnel, filter paper and filter flask which is shown in the picture on top that's how i got my answer
(1) The solubility of Salt AB2(S) IS 5mol/dm^3.
a. Obtain an expression for the solubility product of AB2(S),in terms of s.
b. Calculate the Ksp of AB2,given that solubility is 2.4x10^3mol/dm^3
Answer:
a. Ksp = 4s³
b. 5.53 × 10⁴ mol³/dm⁹
Explanation:
a. Obtain an expression for the solubility product of AB2(S),in terms of s.
AB₂ dissociates to give
AB₂ ⇄ A²⁺ + 2B⁻
Since 1 mole of AB₂ gives 1 mole of A and 2 moles of B, we have the mole ratio as
AB₂ ⇄ A²⁺ + 2B⁻
1 : 1 : 2
Since the solubility of AB₂ is s, then the solubility of A is s and that of B is 2s
So, we have
AB₂ ⇄ A²⁺ + 2B⁻
[s] [s] [2s]
So, the solubility product Ksp = [A²⁺][B⁻]²
= (s)(2s)²
= s(4s²)
= 4s³
b. Calculate the Ksp of AB₂, given that solubility is 2.4 × 10³ mol/dm³
Given that the solubility of AB is 2.4 × 10³ mol/dm³ and the solubility product Ksp = [A²⁺][B⁻]² = 4s³ where s = solubility of AB = 2.4 × 10³ mol/dm³
Substituting the value of s into the equation, we have
Ksp = 4s³
= 4(2.4 × 10³ mol/dm³)³
= 4(13.824 × 10³ mol³/dm⁹)
= 55.296 × 10³ mol³/dm⁹
= 5.5296 × 10⁴ mol³/dm⁹
≅ 5.53 × 10⁴ mol³/dm⁹
Ksp = 5.53 × 10⁴ mol³/dm⁹
Which of the following increases the ratio?
Both β+ and β– decay
Only β– decay
Neither β+ nor β– decay
Only β+ decay
Answer:
Only β+ decay
Explanation:
In positron emission, a proton is converted into a neutron and a positron. An anti neutrino is a particle that serves the purpose of balancing the spins.
During positron emission, the mass number to the daughter nucleus is the same as that of the parent nucleus but the atomic number of the daughter nucleus is less than that of the parent nucleus by one unit.
Positron emission increases the neutron/proton ratio.
Sodium is less reactive than potassium.
Answer:
Sodium atoms due to being smaller in size have high ionization energy and thus, it can't lose electrons easily and is more stable and less reactive. ... Hence, from this it is clear that sodium is less reactive than potassium.
Explanation:
what is the change of state from gas to liquid
Vapourization and condensation. the actual 1 shud be vapourization.
PLEASE ANYONE HELP!!!
How does an increase in -CH2 groups in an organic chain affect the boiling point?
A. The boiling point increases as more -CH2 groups are added.
B. The boiling point increases up to 4 CH2 groups and then begins to decrease.
C. The boiling point is not affected by -CH2 groups, only by functional groups.
D. The boiling point decreases as more -CH2 groups are added.
Answer:
I believe it's a.
Explanation:
The osmotic pressure of a solution formed by dissolving 0.231 g of the protein in 150 mL of water at 298 K is found to be 2.054 torr.
Answer:
13924g/mol is the molar mass of the protein
Explanation:
What is the molar mass of the protein.
The osmotic pressure of a solution, π, is defined as:
π = c*R*T
Where π is osmotic pressure = 2.054torr* (1atm/760torr) = 2.70x10⁻³atm
c is molar concentration of the protein,
R is gas constant = 0.082atmL/molK
And T is absolute temperature = 298K
Solving the molar concentration:
c = π / RT
c = 2.70x10⁻³atm / 0.082atmL/molK*298K
c = 1.106x10⁻⁴ moles protein / L
The moles of protein in 150mL = 0.150L:
0150L * (1.106x10⁻⁴ moles protein / L) = 1.659x10⁻⁵ moles protein
The molar mass is the ratio of mass and moles:
0.231g / 1.659x10⁻⁵ moles protein =
13924g/mol is the molar mass of the proteinA 217.6 sample of gas is collected at 9.011 atm and 127.8°C. What volume does the gas have at 44.9 atm and 11.9 °C?M
Answer:
The correct answer is = 31.04
Explanation:
The relation between volume, temperature and pressure of a fix amount of a gas can be expressed by the combined gas law:
PV/T = k
It can be written as well as
P1V1/T1 = P2V2/T2
Given:
V1 = 217.6
P1 = 9.011 atm
T1 = 127.8°C = 400.95 K
P2 = 44.9
T2 = 11.9 °C = 285.05
Solution:
Putting value in the formula
V2 = P1V1T2/P2T1
= (217.6*285.05*9.011)/44.9*400.95
V2 = 31.04
5. Which choice best represents the relationship between wavelength and frequency?
when frequency decreases, wavelength decreases
there is no relationship
when frequency increases, wavelength increases
O when frequency decreases, wavelength increases
What is the frequency of an electromagnetic wave that has a wavelength of
8.5 x 102 m in a vacuum? (The speed of light in a vacuum is 3.00 x 108 m/s.)
A. 1.2 x 10-3 Hz
B. 2.8 x 10-6 Hz
C. 3.5 105 Hz
D. 2.6 x 1011 Hz
➡ ANSWER
☑ C. 3.5 105 Hz
By referring to the particulate theory of mater, explain the following statement: Oxygen gas is very easy to compress when pressure is applied
By referring to the particulate theory of matter, explain the following statement: A solid lump of iron has a high density .
Answer:
See explanation
Explanation:
According to the particulate theory of matter, gas particles do not interact with each other. A gas is composed of isolated particles moving at high velocities and collide frequently with each other and the walls of the container.
Since the particles of a gas are mostly isolated, it is easy to compress the gas when pressure is applied thereby bringing the gas particles closer together.
On the other hand, in the solid state, the particles that compose matter are close together. These particles only vibrate about their mean positions due to strong intermolecular interaction between particles. The fact that the particles of the solid ion are so close together makes the solid iron lump to possess high density.
Match each word to its correct meaning. 1. carbon sequestration carbon dioxide, water vapor, methane, nitrogen oxides, and some CFCs that absorb heat and keep it in the earth's atmosphere 2. greenhouse effect technology used to capture the carbon released from smokestacks and store it in some part of the environment to keep it out of the atmosphere 3. greenhouse gas a term used to describe the role that greenhouse gases play in keeping the earth warm
Answer:
1. Greenhouse gas.
2. Carbon sequestration.
3. Greenhouse effect.
Explanation:
Greenhouse gases can be defined as gases that trap heat within the Earth's atmosphere. Thus, an increase in global temperature is largely caused due to an increase in the amount of greenhouse gases in Earth's atmosphere.
Some examples of greenhouse gases present in the atmosphere are methane, water vapor, carbon dioxide etc.
Matching the descriptions with their term respectively, we have;
1. Greenhouse gas: carbon dioxide, water vapor, methane, nitrogen oxides, and some CFCs that absorb heat and keep it in the earth's atmosphere
2. Carbon sequestration: it's a technology used to capture the carbon released from smokestacks and store it in some part of the environment to keep it out of the atmosphere. Thus, it's a process that is typically used for capturing and the long-term storage of atmospheric carbon dioxide in soil, ocean, plants and geologic formation, so as to reduce global warming or climate change.
3. Greenhouse effect: it's a term used to describe the negative role that greenhouse gases such as methane, water vapor, carbon dioxide etc., play in keeping the earth warm.
You're a dentist and want your patients to have the cleanest smiles possible. You're not sure which toothpaste to recommend and decide to design an
experiment to determine which toothpaste gives the brightest and whitest smile.
1) What variables would you need to control in your
experiment?
2) Which variable would you change to determine which toothpaste is best?
3) What is the measurable outcome for this experiment?
d) What would the procedure be for your experiment? Please help me to answer this questions:(
Answer:
Why do you need good toothpaste?
Explanation:
Answer:
Do this yourself smh this isnt what the wesite is for
Explanation:
A se ion has a mass number of 77
and a charge of −2
. Determine the number of neutrons, protons, and electrons in this ion.
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.
Learn more about atoms and ions here:
brainly.com/question/18481428
brainly.com/question/1659592?referrer=searchResults
Select the atoms that are likely to gain electrons to form anions:
A. Cesium (Cs)
B. Chlorine (CI)
c. Nitrogen (N)
D. Sulfur (S)
hurryyy asap make u the brainlyeist
Answer:
c
Explanation:
Joelle is a manager at a construction company, and she is interested in the chemistry behind the materials they use. She has begun studying the materials used to fill walls. She knows that to keep the temperature inside a room steady the material must be a thermal insulator, and she predicts that materials should not be acidic or else they would dissolve too easily in water. Which of these is a molecular ingredient that could be used in a wall-filling material ?
Answer: C6H6
Explanation:
The molecular formula C₆H₆ represents Benzene. Benzene is colorless, flammable, and has a sweet and gasoline-like odor. It's a toxic chemical, and can cause cancer.
Benzene is a hydrocarbon and used for the manufacturing of products such as plastic, detergents, glues, dyes, and rubber. It can also be used in making wall-filling material.
Answer: C6H6
Explanation:
The molecular formula C₆H₆ represents Benzene. Benzene is colorless, flammable, and has a sweet and gasoline-like odor. It's a toxic chemical, and can cause cancer.
Benzene is a hydrocarbon and used for the manufacturing of products such as plastic, detergents, glues, dyes, and rubber. It can also be used in making wall-filling material.
name the gas which is formed when coal is heated in the absense of air
Answer:
Coke
Explanation:
A solid fuel formed by heating coal in the absence of air is coke. Coke is black colored, tough porous substance. It is pure carbon.
0.18 g of a divalent metal was completely dissolved in 250 cc of acidsolution containing 4.9 g H2SO4 per liter. 50 cc of theresidual acid solution required 20 cc of N/10 alkali forcomplete neutralization. Calculate the atomic weight of metal.
goodnight Gucci chunk cubic DDF if f Ch BK
Antara berikut ciri manakah bear tentang cuka?
A. Berasa pahit.
B. Berasa tawar.
C. Nilai pH kurang dari 7
D. Nilai pH ialah 7
Answer:
c. nilai pH kurang dari 7
Explanation:
cuka adalah acid
nilai pH bagi acid adalah
antara 1 hingga 6
name any two mix metals with one use from each.
Answer:
bronze, copper
Explanation:
bronze is used to make medals and carve statues
copper is used to make wire and utensils
los metales se oxidan
what are the difference between ionic bond and covalent bond?
Which is stronger?
QUËSTIONS :- what are the difference between ionic bond and covalent bond?
IONIC BONDS :- THEY R BONDS WHICH R FORMED DUE TO THE COMPLETE TRANSFER OF ELECTRONS BETWEEN TWO ATOMS
COVALENT BONDS :- THEY R THE BONDS WHICH R FORMED DUE TO INCOMPLETE TRANSFER OF ELECTRONS BETWEEN TWO ATOMS
IONIC BONDS R MORE STRONGER.
Explanation:
Ionic bond is much stronger than covalent bond because it involves complete transfer of electrons because of which there is formation of cation and anion and there exist huge electrostatic forces of attraction. They also have high melting and boiling point which proves that the ionic bond is very strong.
Differences between ionic bond and covalent bond :
Ionic Bonds. Covalent Bonds
Polarity :High. Low
Shape : No definite shape. Definite shape
Melting Point :High Low
Boiling Point: High Low
A cart accelerating slower when mass was increased.
1st Law - 3rd Law
Answer:
Newton's second law
Explanation:
It is mentioning acceleration and mass
Newton's second law's equation = F = m*a
Hope u understood
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Thank You
What type of reaction is shown below?
H202 + H2O + O2
Single replacement
Combustion
Synthesis
Decomposition
Answer:
Decomposition Reaction
Equal mases of ethane and hydrogen are mixed in an empty container at 25 degree celcius.The fraction of the total pressure exerted by hydrogen is
Answer:
15/16
Explanation:
We need to find the number of moles of hydrogen and number of moles of ethane present.
Since we have the same mass, m for both substances, the number of moles of hydrogen, n = m/M where M = molar mass of hydrogen molecule
Since hydrogen is H₂, M = 2 × 1 g/mol = 2 × 1 g/mol = 2 mol.
n = m/M
n = m/2
Also, number of moles of ethane, n' = m/M' where M' = molar mass of ethane.
Since ethane is C₂H₆, M' = 2 × 12 g/mol + 6 × 1 g/mol = 24 g/mol + 6 g/mol = 30 g/mol
n' = m/M'
n' = m/30
The total number of moles of gas present is thus n" = n + n' = m/2 + m/30 = (15m + m)/30 = 16m/30
The mole fraction of hydrogen is thus number of moles of hydrogen/total number of moles = n/n" = m/2 ÷ 16m/30 = m/2 × 30/16m = 15/16
Also, since the partial pressure due to hydrogen, P = mole fraction × total pressure, P'
P/P' = mole fraction = 15/16
So, The fraction of the total pressure exerted by hydrogen is 15/16
Nombra cada uno de los siguientes hidrocarburos de acuerdo a las reglas de la IUPAC
Answer:
i) ciclobutano
ii) 3-etil-4-metil ciclopenteno
Explanation:
Toda la idea de la nomenclatura IUPAC es permitir que la estructura de la sustancia se derive de su nombre y viceversa.
La nomenclatura IUPAC es un sistema universalmente aceptado para nombrar compuestos químicos.
los nombres de los compuestos enumerados son;
i) ciclobutano
ii) 3-etil-4-metil ciclopenteno
which is an example of the force of attraction between two obects that have mass?
Answer:
gravity
Explanation:
Gravity is an example of the force of attraction between two objects that have mass.
