Answer:
.59 g
Explanation:
5.6 d / 3.9 d /half life = 1.436 half lives
(1/2)^1.436 = .3696 of original left
.3696 * 1.6 = .59 gm
A sample contains 2.2 g of the radioisotope niobium-91 and 15.4 g of its daughter isotope, zirconium-91. how many half-lives have passed since the sample originally formed? half-lives
The number of half-lives that has elapsed since the sample originally formed is 3 half-lives
Data obtained from the questionOriginal amount (N₀) = 15.4 + 2.2 = 17.6 g
Amount remaining (N) = 2.2 g
Number of half-lives (n) = ?
How to determine the number of half-lives that has elapsed2ⁿ = N₀ / N
2ⁿ = 17.6 / 2.2
2ⁿ = 8
2ⁿ = 2³
n = 3
Thus, 3 half-lives has elapsed
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Answer:
3
Explanation:
e2022
The elements of a group have the same number of ___________________ in their ______________ shell
Answer:
Same amoung of electrons in their outer shell
Explanation:
elements in the same group have the same number of electrons in their outer shell this is why they are in the same group
The elements of a group have the same number of valence electrons in their outermost shell.
Why do the elements of the same group have similar chemical behavior?The chemical properties of elements are described by the number of valence electrons in their outermost shell. The chemical elements placed in the same group have the same number of valence electrons in their valence shell. Therefore, the chemical elements placed in the same group of the periodic table have similar chemical behavior.
The elements having identical valence electronic configurations in their atoms are arranged in the same group of the modern periodic table. These valence electrons are accountable for the chemical properties and reactivities of the elements.
For example, the chemical properties of all elements in group 1 are similar as they have only one electron in their valence shell. The chemical elements of group 17 have seven electrons in their valence shell they are halogens with similar chemical behavior.
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A gas at 200 Celsius and 10.0L expands to 20.0L. What is the new temperature in Celsius
Answer:
400celcius
Ex:
200 per 10.0L
400 per 20.0L
A 2.75 M solution is diluted to 0.706 M, if the starting volume was 0.833L, what is the new volume?
Answer:
3.2447
Explanation:
m1v1 = m2v2
Select all the following solutions that would be expected ph values for basic solutions?
ph 7
ph 9
ph 12
ph 5
ph 10
Answer:
9, 10, 12
Explanation:
anything greater than pH 7 is basic
Dominic and Eva are using the same type of stopwatches to measure the time it takes for a chemical reaction to occur. They each use the same stopwatch to measure the time. These are their results:
Person Trial 1
Dominic 78 seconds
Eva 81 seconds
Why are their results unreliable and can lead to a pseudoscientific claim?
They did not repeat their tests multiple times.
They used the same type of stopwatch.
They did not change the reactants in their chemical reactions.
Only one person should have collected the data.
The attraction of hydrogen to oxygen in a water molecule has unequal sharing of electrons, caused by a(n) _____.
A. metallic bond
B. nonpolar covalent bond
C. covalent bond
D. ionic bond
E. polar covalent bond
Answer:
c
Explanation:
got it right on my test
Answer:
The answer is: C aka covalent bond
Explanation:
Happy to help
How many milliliters of a 0.1000 M NaOH solution would be needed to neutralize a 1.0000-g sample of potassium hydrogen phthalate (KHC8H4O4) to a phenolphthalein endpoint, according to the following balanced equation?
KHC8H4O4(s)+NaOH(aq)------> KNaC8H4O4(aq)+H2O(l)
Answer: 2) 2HCl(sq) + CaCO3(s) CaCl2(sq) + CO2(g) + H2O (l) No of moles of CaCO3 = amount of the CaCO3 (g)/mw of CaCO3 (g/mole)= 0.8085 g/100 g/mole = 0.008085
Explanation:
How many moles of carbon dioxide are produced if 50.0 L of oxygen is used?
How many ml of naoh was used to reach the equivalence point?
options:
10ml
20ml
25ml
50ml
A 28. 0 ml sample of vinegar, which is an aqueous solution of acetic acid, ch3cooh, requires 21. 5 ml of 0. 550 m naoh to reach the endpoint in a titration
Concentration of vinegar sample of 28mL which requires 21. 5 ml of 0.550 M NaOH to reach the endpoint in a titration is 0.42M.
How do we calculate the concentration of Vinegar?Concentration of vinegar in the titration method will be used by using the below equation:
M₁V₁ = M₂V₂,
M₁ & V₁ are the molarity and volume of acetic acid.M₂ & V₂ are the molarity and volume of vinegar sample.By putting values on above equation from the question, we get
M₂ = (0.55M)(21.5mL) / (28mL) = 0.42 M
Hence, required concentration of vinegar is 0.42M.
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The ph of a. 25m aqueous solution of hf is 2. 3. What is the value of ka for hf?
pH is the concentration of the hydrogen ion in the solution. The value of Ka for hydrogen fluoride is 2.7688.
What is pH?pH is the potential of the hydrogen or the hydronium ion in the solution that depicts the acidic or the basic character of the solution.
Given,
pH = 2.3
Concentration of hydrogen fluoride = 0.25 M
The concentration of hydrogen ion is calculated as:
[tex]\begin{aligned} \rm pH & = \rm - log [H^{+}]\\\\2.3 &= \rm - log [H^{+}]\\\\&= 0.832\;\rm M\end{aligned}[/tex]
Ka is calculated as:
[tex]\begin{aligned} \rm Ka &= \rm \dfrac{[H^{+}]F^{-}]}{[HF]}\\\\&= \dfrac{0.832 \times 0.832}{0.25}\\\\&= 2.7688\end{aligned}[/tex]
Therefore, 2.7688 is the Ka for hydrogen fluoride.
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You've found some fossil bones while digging in your backyard. Could they be dinosaur bones? Using carbon dating, you determine that 3% of the original radioactive carbon-14 is still radioactive. (The rest has decayed into nitrogen-14.) How many half-life cycles has it gone through?
The half-life of Carbon-14 is 5730 years. When did the animal die?
Answer:
5 is the first answer and 28,650 for second
How many atoms in Ga2Se3
- 35. Which of the following processes are exo- thermic? Endothermic?
A reactant and a product of nuclear fission.
A. Neutron
B. Gamma
Answer:
Neutron
Explanation:
NaOH (aq) + CuSO4(aq) →
balance the equation.
why global warming is a big problem to us
Explanation:
Global warming indeed is a big problem to us. But not only us, it is a big problem to all living things on the Earth. Global warming as everyone knows is a topic that has been with us for a long time. Global warming happens in multiple ways like deforestation, due to harmful gases (Like carbon doxide) and etc... Global warming simple means that our Globe is warming or is heating up. This is a big problem to all living things on Earth.
It is a big problem to us because increase in temperature throughout the globe and due to this Ice in the Antarctic and the Arctic is melting and is causing damage to habitat of animals and also this is causing the sea level to rise and also this is wasting drinking water that us humans have. So this is clearly a problem to all.
But there is good news that now because people are now starting to care for the planet by reducing the amount of harmful gases released to the environment and also starting Reforestation programs.
So In my opinion Global warming is a big problem to all living things on Earth.
Most scientists use scientific methods in which of the following orders
Answer:
Experiment, analysis, research, purpose, hypothesis and conclusion.
Find the hydrogen ion concentration of a saturated solution of calcium hydroxide whose ph is 13. 1
The pH of the solutions is 12.67.
What is pH of a Solution?
pH is the measurement of how acidic or basic a solution is. The range of pH values is from 0 to 14. Lower pH values mean higher acidity, while higher pH means higher basicity. If the pH value is equal to 7, then the solution is neutral.
To calculate the pH of the solution, a few approaches are possible. Here, the pOH of the solution is calculated first using the molar concentration of [tex]OH^{-1}[/tex] ions. Because pH + pOH = 14, the pH of the solution can then be calculated by subtracting pOH from 14.
Because 2 moles of [tex]OH^{-1}[/tex] ions are formed per mole of [tex]Ca(OH)_{2}[/tex]dissolved, the pOH of a saturated [tex]Ca(OH)_{2}[/tex] solution at [tex]20^{.C}[/tex] is,
Concentration ([tex]C_{OH}[/tex]) of [tex]OH^{-1}[/tex] ions,
[tex]C_{OH}[/tex] = 0.02335 mol [tex]Ca(OH)_{2}[/tex]/L X 2 mol [tex]OH^{-1}[/tex] /1 mol [tex]Ca(OH)_{2}[/tex]
[tex]C_{OH}[/tex] = 0.0467 mol [tex]OH^{-1}[/tex]/L
*pOH of saturated [tex]Ca(OH)_{2}[/tex] solution,
pOH = -log [[tex]C_{OH}[/tex]]
pOH = -log [0.0467 mol [tex]OH^{-1}[/tex]/L ]
pOH = 1.33
*pH of saturated [tex]Ca(OH)_{2}[/tex] solution,
pH = 14 - 1.33
pH = 12.67
Hence, the pH of the solutions is 12.67.
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A gas sample has a volume of 126 ml at 58. 0∘c. What is the volume of the gas at 118∘c
Answer:
148.8 ml
Explanation:
V1/T1 = V2/T2
T2 * V1/T1 = V2 (T must be in K units)
(118 + 273.15) * 126 /(58 + 273.15) = 148.8 ml
If a reactant is in excess, why do we not worry about the mole ratios involving that reactant?.
Answer: The limiting reactant will be used up first, meaning the reaction can no longer occur with only the excess reactant.
Explanation:
In a reaction the reactant which determines the yield of the reaction is called limiting reactant. Whereas, the reactant which is excess in amount does not itself lead the reaction after the limiting reactant is consumed.
What is excess reactant?In a reaction, the yield of the product depends on the number of moles of reactants. The reactants which is not sufficient in amount is determining the yield because as soon as this reactant is consumed, the production stopes.
The excess reactant on the other hand is excess in amount which can't lead the reaction alone after the consumption of the limiting reactant. Hence, we don't have to worry on the excess reactant.
The limiting reactant of a reaction can be determined by calculating the number of moles of each reactants participating in it.
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Can I get help in #6 ?
option A Hydrogen will have the greatest rate of effusion beacuse it has the least mass among all
Base your answer to the question on the information below given the reaction at equilibrium2NO2(g)+7H2(g)->-< 2NH3(g)+4H2O(g)+1127kJ which diagram below correctly shows the potential energy diagram for the forward reaction, including the activation energy and the potential energy of the products?
Answer: 1
Explanation:
Heat is being released, so the energy of the reactants is less than the energy of the products.
salt seems to disappear when it is poured into water use the terms mixture solution and dissolve to explain what happens
Answer:
water acts as a solvent and dissolves the solute (salt) to produce a salt water solution
Explanation:
What is the pH of a solution whose [H⁺] is 2.7 x 10⁻⁴ M?
Answer:
Here is the solution..Hope it helps:)
What does the shape of the moon we see depend on?
The position of the moon during its orbit around Earth
The position of the moon during its orbit around Jupiter
The position of the moon during its orbit around Mars
The position of the moon during its orbit around Saturn
Answer:
The position of the moon during its orbit around Earth
Answer:
the angle you look at it from
What is the difference between ethanol and methanol.
what was the significance oh Rutherford's expierment
Answer:
His gold foil experiment showed that the atom is mostly empty space with a tiny dense positively-charged nucleus. Based on those results, Rutherford was able to propose the nuclear model of the atom.
which property can be used to help identify many minerals?
Answer:
Minerals can be identified by their color, luster, streak, cleavage, hardness, and even by their chemical composition. Using these properties is one way a Geologist defines and identifies what kind of mineral a specimen is.
