Answer is: atomic number
of resulting atom is 88.
Alpha particle is nucleus of a helium-4 atom, which is made of
two protons and two neutrons.
Nuclear reaction: ²³²Th → ²²⁸Ra + α (alpha
particle).
Alpha decay is radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and transforms into an atom with an atomic number that is reduced by two and mass number that is reduced by four.
Potassium-40 has a half-life of 1.3 billion years. as the potassium-40 isotope decays, it becomes argon. if a rock was formed with 12 g of potassium-40, approximately how long would it take for 75% of the potassium-40 to be replaced by argon?
a. 1.3 billion years
b. 2.6 billion years
c. 5.2 billion years
d. 650 million years
Final answer:
It takes two half-lives, or 2.6 billion years, for 75% of Potassium-40 to decay to Argon, making (b) 2.6 billion years the correct option.
Explanation:
The decay of Potassium-40 (K-40) to Argon (Ar-40) follows the principles of radioactive decay and the concept of half-lives. The half-life is the time it takes for half of the original quantity of a radioactive isotope to decay. In this case, K-40 has a half-life of approximately 1.3 billion years. After one half-life, there would be 6 grams of K-40 and 6 grams of Ar-40. After two half-lives, which is 2.6 billion years, there would be 3 grams of K-40 and 9 grams of Ar-40. Since the question asks for the time it would take for 75% of the potassium-40 to be replaced by argon, we are looking for the time it takes to have only 25% of the original K-40 remaining.
Starting with 12 grams of K-40, after the first half-life, we would be left with 6 grams of K-40, which is 50%. After the second half-life, we would be left with 3 grams of K-40, which is 25% of the original amount. Therefore, it would take two half-lives for 75% of the potassium-40 to decay to argon, which equates to 2.6 billion years. The correct option is therefore (b) 2.6 billion years.
HELP! 30 POINTS!!
2. Which of the following statements are true about a strong base and a weak base at a pH of 11?
HCl will not bring the pH of either solution to pH 7.
Both bases require the same amount of HCl to reach pH 7 because they are both
at the same initial pH.
The weak base will require less HCl to bring the pH to 7 than the strong base. The strong base will require less HCl to bring the pH to 7 than the weak base.
the answer is definatly A
If the volume occupied by 0.500 mol of nitrogen gas at 0°C is 11.2 L, then the volume occupied by 2.00 mol of nitrogen gas at the same temperature and pressure will be:
A. the data given is not sufficient to determine the volume
B. 22.4 L
C. 44.8 L
D. the same as that occupied by 0.500 mol of nitrogen gas
If 25.0 ml of seawater has a mass of 25.895 g and contains 1.295 g of solute, what is the mass/mass percent concentration of solute in the seawater sample? 5.18% 5.001% 3.862% 96.5% 20.00%
What is the ph of an acetic acid solution if 10 drops are titrated with 70 drops of a 0.65 m koh solution? (ka for acetic acid = 1.8 x 10-5)?
Which best describes the tyndall effect? the scattering of light by solutes in a mixture the scattering of light by solvent in a solution the scattering of light by solutes in a solution the scattering of light by particles in a mixt?
the scattering of light by particles in a mixture
Answer:The correct answer is option:'the scattering of light by particles in a mixture'.
Explanation:
Tyndall effect is defined as scattering of the light by the particles present in the mixture. A beam of the light passing through these mixture are visible to the human eyes. Generally colloidal mixture displays this type of effect. The name of his effect is named after the physicist named John Tyndall.
Hence, the correct answer is option:'the scattering of light by particles in a mixture'.
The formula for the illegal drug cocaine is c17h21no4 (303.39 g/mol). what is the percentage of hydrogen in the compound? 21.09% 4.618% 67.30% 6.991% 3.959%
How many moles of KNO3 are needed to make 600 ml of a 1.3M solution?
To make a 1.3M solution with a volume of 600 ml, you would need 0.78 moles of KNO3.
Explanation:To calculate the number of moles of KNO3 needed to make a 1.3M solution, we can use the equation:
Molarity (M) = moles of solute / liters of solution
Rearranging the equation, we can solve for moles of solute:
Moles of solute = Molarity x liters of solution
In this case, the molarity is 1.3M and the volume is 600 ml (which is equivalent to 0.6 L). Substituting these values into the equation:
Moles of KNO3 = 1.3M x 0.6 L = 0.78 moles
A sample of oxygen gas has a volume of 150. milliliters at 300 k. if the pressure of the sample is held constant and the temperature is raised to 600 k, the new volume of the sample will be
Answer:
The new volume of the sample will be 300 milliliteres
Explanation:
We were given the following;
Initial Volume (V1) = 150ml
Initial Temperature (T1) = 300K
Final Temperature (T2) = 600K
Final Volume (V2) = ?
Pressure is held constant.
The law applicable in solving this question is that of Charle's law. This law states that the volume of a fixed mass of gas varies proportional to the temperature at constant pressure.
The formula is given as;
[tex]\frac{V1 }{T1} = \frac{V2 }{T2}[/tex]
Solving for V2. we have;
[tex]V2 = \frac{V1T2}{T1}[/tex]
V2 = ( 150 * 600) / 300
V2 = 300 ml
Describe two negative effects that water pollution can have on the environment. Explain one way water pollution can be reduced.
Answer:
1) Adverse effect on aquatic life also increase in biological oxygen demand.
2) Biomagnification of pollutants
Explanation:
Water pollution is caused by unwanted addition of waste, animal debris, industrial effluents etc in a water body.
Water pollution may cause many direct and indirect harmful effects on environment. To name a few:
a) Decrease in level of oxygen leading to death of aquatic organism like fish.
Increase in biological oxygen demand.
b) Biomagnification: a pollutant may enter food chain from water and some pollutant may enter food chain contaminating other members of food chain.
The pair of elements that forms a bond with the least ionic character is
A. Na and Cl
B. K and Cl
C. O and Cl
D. Mg and Cl
The pair of O and Cl elements forms a bond with the least ionic character.
The ionic character of the bond depends on the electronegativity difference. The bonds having an electronegativity difference of greater than 1.7 have more ionic character.
(A) In bond between Na and Cl, the electronegativity difference =
Electronegativity of Cl - electronegativity of Na
= 3.16 - 0.93
= 2.23
(B) In bond between K and Cl
= electronegativity of Cl - electronegativity of K
= 3.16 - 0.82
= 2.34
(C) In bond between O and Cl:
= electronegativity of O - electronegativity of Cl
= 3.44 - 3.16
= 0.17
(D) In bond between Mg and Cl:
= electronegativity of Cl - electronegativity of Mg
= 3.16 - 1.31
= 1.85
Since the bond between O and Cl has the least electronegativity difference, thus have the least ionic character.
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Why can 6-aminohexanoic acid undergo a polymerization reaction with itself?
Answer: Functional groups can lead to intra molecular condensation.
Explanation: 6 -aminohexanoic acid is a molecule which have 2 functional groups - one is amine group (-NH2) and the other one is carboxylic group (-COOH).
The non bonding electrons or lone pairs present on the amine group being nucleophillic in nature will attack on the electrophillic carbon of carboxylic group to form the amide bond, the structure of which is hereby attached.
Thus due to the presence of 2 active functional groups, polymerization with itself can take place easily.
As the moisture-rich air approaches the mountain, it rises and cools, and water molecules in the air combine to form small drops. the process where water vapor becomes a liquid is called ____________
A ping pong ball with a dent in it can be put into a pan of boiling water. After a short amount of time, the dent will pop out. Explain why this occurs.
Answer:
The right option is; b. the water caused an increase in temperature of the air inside the ball and an increase in pressure.
The dent (hollow area formed by pressing or hitting) from the ping-pong ball disappeared because energy was transferred from the hot boiling water in which the ball was placed to the air inside the ball. This transferred energy will increase the temperature of the air inside the ball and the air molecules will begin to move faster with a greater force. Hence, causing an increase in pressure.
Explanation:
Which nuclear emission has the greatest penetrating power?
b. beta particle
a. proton
c. gamma radiation
d. positron
Answer:gamma radiation
Explanation:
Among the nuclear emissions including proton, beta particle, positron and gamma radiation, gamma radiation has the greatest penetrating power. It needs dense materials like lead or concrete to be shielded.
Explanation:Of the nuclear emissions listed: a. proton, b. beta particle, c. gamma radiation, and d. positron, the one with the greatest penetrating power is c. gamma radiation. Unlike other particles, gamma radiation is a type of electromagnetic radiation, similar to X-rays. This means it is not a charged particle, allowing it to penetrate materials more easily.
For instance, alpha and beta particles would be blocked by a piece of paper or the surface of the human skin, but gamma rays can penetrate much deeper, requiring dense materials like lead or concrete for shielding.
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1. What is the pH of a 0.085 M solution of nitrous acid (HNO2) that has a Ka of 4.5 × 10-4?
2.21
5.33
3.35
4.42
Write out the balanced equation for the reaction that occurs when Mg(OH)2 and HCl react together.
Answer:
The balanced equation for the reaction that occurs when Mg(OH)2 and HCl react together is:
Mg(OH)2+2HCl -------->MgCl2+2H20
How much is 2.50 g of CuCl2 in moles ?
What kind of reaction occurs when the entropy change of an endothermic reaction is negative?
Gibbs free energy
(G) determines if reaction will proceed spontaneously.
ΔG = ΔH - T·ΔS.
ΔG - changes in Gibbs free energy.
ΔH - changes in enthalpy.
ΔS - changes in entropy.
T is temperature in Kelvins.
When ΔS < 0 (negative entropy change) and ΔH > 0
(endothermic reaction), the process is never spontaneous (ΔG> 0).
Answer:
reaction is nonspontaneous under standard conditions at all temperatures.
Explanation:
took the test.
What number of moles of solute are present in 25.0 mL of 2.00 M HCl?
The number of moles of solute that are present in 25.0 mL of 2.00 M HCl is equal to 0.05 moles.
How do we calculate moles from molarity?Molarity (M) of any solution is define as the number of moles (n) of solute present in per liter of the solution (V) and represented as:
M = n/V
Given that, Volume of solution = 25mL = 0.025L
Molarity of HCl = 2M
Moles = (2)(0.025) = 0.05 moles
Hence required moles of solute are 0.05 moles.
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N2 (g) + 3H2 (g) -->2 NH3 (g) The equation above is the equation for the Haber process. In a certain reaction, you start with 3.0 moles of nitrogen and 5.0 moles of hydrogen, How much of the excess reactant will be left over after the reaction?
H₂ is in excess and N₂ will be completely consumed in the reaction.
Explanation:According to the balanced equation, 1 mole of N₂ reacts with 3 moles of H₂ to produce 2 moles of NH₃. In this particular reaction, you have 3.0 moles of N₂ and 5.0 moles of H₂. To determine the limiting reactant, you need to compare the moles of each reactant to the stoichiometric ratio. In this case, the ratio of moles of N₂ to H₂ is 1:3. Since you have more moles of H₂ (5.0) compared to the stoichiometric ratio, H₂ is in excess. Therefore, all of the N₂ will be completely consumed and there will be no N₂ left over after the reaction.
How many nitrogen molecules are in a 8.86 L container of nitrogen gas at a pressure of 112.1 kPa and a temperature of 30.8 oC?
Which of the following is an example of chemical weathering? a. waves washing over rocks on the beach b. acid rain falling on sidewalks c. ice forming in the cracks of rocks d. wind blowing against rocks
Answer:
b. Acid rain falling on sidewalks
Explanation:
Hello,
Acid rain contains majorly carbonic acid [tex]H_2CO_3[/tex] which could react with the concrete that is used to make sidewalks. This chemical reaction, although varies based on the concrete's composition, usually gives off carbon dioxide owing to the acid's instability and leads to the weathering since the sidewalks start to wear out and subsequently break down.
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Sedimentary rocks formed from the remains of once-living things are
The correct option is D. This type of rock is called biologic sedimentary rock. It is formed from accumulation of dead living things which have been compressed and cemented together to form a rock.
Please advise if this is your complete question entirely? If yes, then your correct answer is provided above.
Sedimentary rocks formed from the remains of once-living things are ____.
a. metamorphic
c. organic
b. detrital
d. none of the above
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How many sites on this antibody molecule have potential to bind to a non-self molecule?
Which equation represents the half-reaction that takes place at the fork?
What's the definition of ions
In the formation of a solution how does the solvent differ from the solute
Which of the following energy yields is most likely to have come from a fission or a fusion reaction?
Answer:
D. 2.0 x 10^11 kJ/mol
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Why do covalent compounds tend to have lower melting points than ionic compounds?
The forces of attraction in covalent compounds are weaker than those in ionic compounds as they are formed by sharing of electrons.
What are covalent compounds?Covalent compound is defined as a compound which is formed by the mutual sharing of electrons to form electron pairs between the two atoms.These electron pairs are called as bonding pairs or shared pair of electrons.
Due to the sharing of valence electrons , the atoms are able to achieve a stable electronic configuration . Covalent bonding involves many types of interactions like σ bonding,π bonding ,metal-to-metal bonding ,etc.
Sigma bonds are the strongest covalent bonds while the pi bonds are weaker covalent bonds .Covalent bonds are affected by electronegativities of the atoms present in the molecules.Compounds having covalent bonds have lower melting points as compared to those with ionic bonds.
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