The question is incomplete, the complete question is;
Cesium-137 is radioactive and has a half life of 30. years. Calculate the activity of a 6.8 mg sample of cesium-137. Give your answer in becquerels and in curies. Round your answer to 2 significant digits Bq Ci
Answer:
See explanation
Explanation:
The formula for activity is;
R= 0.693N/t1/2
N= 6.02 ×10^23 mol × 6.8 ×10^-3g/137 g/mol = 3 × 10^19
Substituting into the formula;
R= 0.693 × 3 × 10^19/30 years
R= 6.93 ×10^17 y^-1
In Bq;
6.93 ×10^17 y^-1 × 1.00y/3.16 ×10^7 seconds
= 2.19 ×10^10 Bq
In Ci;
2.19 ×10^10 Bq/3.7 ×10^10 Bq/Ci
= 0.59 Ci
What is the empirical formula for a compound that is comprised of 54.0% sodium, 8.50% boron, and 37.5% oxygen by mass
Answer:
Sodium metaborate: sodium+boron+oxygen= NaBO 2.
The formula can be written also as Na 2O·B
Explanation:
30 points!!!!
2K + 2H2O → 2KOH + H2
This reaction shows which detail about potassium and hydrogen?
Hydrogen is more reactive than potassium.
Potassium and hydrogen form ionic bonds.
Potassium is more reactive than hydrogen.
Potassium and hydrogen form covalent bonds
Answer:
2K + 2H2O → 2KOH + H2
So Hydrogen is more reactive than pottasium .
According to law of conservation of matter, 2 moles of potassium react with water to produce 1 mole of hydrogen gas.So, 2 moles of potassium produce 1 mole of hydrogen gas.Answer:
A
Explanation:
Hydrogen is more reactive than potassium.
How can a redox reaction be identified?
O A. Atoms have rearranged.
O B. Protons have been transferred.
.
O
C. lons are present in solution.
D. Oxidation states have changed.
Answer:
'Oxidation states have changed.'
Explanation:
Redox Reactions can be identifiable by a change in oxidation number/states of two of the atoms in the reaction. Any reaction in which no oxidation numbers/state change is not a redox reaction.
14. pH value are basic are greater than what number while acids are have a pH less than
this value?
Answer:
Less than 7 ph value are acidic. Greater than 7 ph value are basic.
What is the molarity of aqueous lithium bromide if 25.0 mL of LiBr reacts with 10.0 mL of 0.250 M Pb(NO 3) 2
The molarity of aqueous lithium bromide, LiBr solution is 0.2 M
We'll begin by calculating the number of mole of Pb(NO₃)₂ in the solution.
Volume = 10 mL = 10 / 1000 = 0.01 L Molarity of Pb(NO₃)₂ = 0.250 MMole of Pb(NO₃)₂ =?Mole = Molarity x Volume
Mole of Pb(NO₃)₂ = 0.25 × 0.01
Mole of Pb(NO₃)₂ = 0.0025 mole
Next, we shall determine the mole of LiBr required to react with 0.0025 mole of Pb(NO₃)₂
Pb(NO₃)₂ + 2LiBr —> PbBr₂ + 2LiNO₃
From the balanced equation above,
1 mole of Pb(NO₃)₂ reacted with 2 mole of LiBr.
Therefore,
0.0025 mole of Pb(NO₃)₂ will react with = 2 × 0.0025 = 0.005 mole of LiBr
Finally, we shall determine the molarity of the LiBr solution
Mole = 0.005 mole Volume = 25 mL = 25 / 1000 = 0.025 L Molarity of LiBr =?Molarity = mole / Volume
Molarity of LiBr = 0.005 / 0.025
Molarity of LiBr = 0.2 M
Learn more about molarity: https://brainly.com/question/10103895
convert 8.4 • 10^16 molecules of CO2 to moles
Answer:
0.00000000000000084
Explanation:
Which condition is usually associated with low air pressure systems?
Answer:
clouds and precipitation that minimize temperature changes throughout the day
Explanation:
what is the name of the compound CaCo3
Pure silver has a brilliant white metallic luster. How many moles of silver, Ag, are in 7.54 × 1023 atoms of silver?
The number of moles of silver, Ag, that are in 7.54 × 10²³ atoms of silver is 1.25 moles
From the question,
We are to determine the number of moles of silver, Ag, that are present in 7.54 × 10²³ atoms of silver
From the formula
[tex]Number\ of\ moles =\frac{Number\ of\ atoms}{Avogadro's\ constant}[/tex]
Avogadro's constant = 6.022 × 10²³ atoms mol⁻¹
and
From the given information
Number of silver atoms = 7.54 × 10²³ atoms
Putting the parameters into the formula, we get
Number of moles of silver present = [tex]\frac{7.54\times 10^{23} }{6.022\times 10^{23}}[/tex]
Number of moles of silver present = 1.2520757 moles
Number of moles of silver present ≅ 1.25 moles
Hence, the number of moles of silver, Ag, that are in 7.54 × 10²³ atoms of silver is 1.25 moles
Learn more on calculating number of moles here: https://brainly.com/question/15839520
How many ml of a 2.903 M NaOH solution are needed to produce 500.0 ml of a 0.3344M solution?
Answer:
About 57.60 mL.
Explanation:
We can utilize the dilution equation:
[tex]\displaystyle M_1V_1 = M_2V_2[/tex]
Where M are the molarities of the solutions and V are the volumes of the solutions.
We want to determine the volume of a 2.903 M NaOH solution to mix in order to produce 500.0 mL of a 0.3344 M solution.
Substitute and solve for V₁:
[tex]\displaystyle \begin{aligned} (2.903 \text{ M})V_1 & = (0.3344 \text{ M})(500.0 \text{ mL}) \\ \\ V_1 & = 57.60\text{ mL} \end{aligned}[/tex]
In conclusion, 57.60 mL of a 2.903 M NaOH solution is needed.
what is the name of the compound N2O5
Answer:
Dinitrogen pentoxide also known as Nitrogen pentoxide or nitric anhydride (these are all the same thing just different names people call them)
Convert 1.16 mol of calcium cyanide, Ca(CN)2, to mass.
The gas in a 250. mL piston experiences a change in pressure from 1.00 atm to 2.25 atm. What is the new volume (in mL) assuming the moles of gas and temperature are held constant?
Answer:
111.11 mLExplanation:
Since the moles of gas and temperature are held constant the new volume can be found by using the formula for Boyle's law
[tex]V_2 = \frac{P_1V_1}{P_2} \\[/tex]
where
P1 is the initial pressure
P2 is the final pressure
V1 is the initial volume
V2 is the final volume
From the question
P1 = 1 atm
P2 = 2.25 atm
V1 = 250 mL
We have
[tex]V_2 = \frac{250 \times 1}{2.25} = \frac{250}{2.25} \\ = 111.1111111...[/tex]
We have the final answer as
111.11 mLHope this helps you
what is wrong with the statement? "because there are no common factors in the molecular formula, k2co3 is also the empirical formula of potassium carbonate"
The empirical formula is the same as the molecular formula because the ratio of atoms in the compound correspond to the number of atoms of each element in the compound.
The empirical formula of a compound shows the ratio of atoms of each element in the compound while the molecular formula shows the number of atoms of each element in the compound.
For the compound, K2CO3, the empirical formula is the same as the molecular formula because the ratio of atoms in the compound correspond to the number of atoms of each element in the compound. It has nothing to do with common factors.
Learn more: https://brainly.com/question/11588623
What is always true about lenses?
Answer: They all bend light.
i don't know much about lenses so i hope this helps! :)
NO BOTS PLEASE HELP
How many moles are present in 885.46 grams of sodium bicarbonate NaHCO 3 ) ? Molar mass of sodium bicarbonate ( NaHCO 3 )=84.01 g/mol A. 6.3471 x 10^ 24 moles; 0.9877 * 10 ^ - 2 * m * o * l * e * s C. 10.540 moles D 84.007 moles
Answer:
C. 10.540 moles
Explanation:
divide grams by molar mass to get moles
KOH(Ac) + HNO3 → KNO3(Ac) + H2O
cual es su reacio
Answer:
corbonization for dictionnal
Explanation:
correct
Answer:
neutralization reaction forms water and salt , neutralization is the reaction!
Explanation:
Please help me with this question please just help me with what is this is or synthesis singlereplacement
combustion
decomposition
double replacement
Answer:
1) Combustion
2)Synthesis
3)Single Replacement
4)Decomposition
5)Double Replacement
6)Synthesis
7)Double Replacement
8)Single Replacement
9)Combustion
10)Decomposition
Explanation:
Remeber, decomposisition is breaking things apart, synthesis is building them, cobusion will always make water and CO2 and will always burn O2, single replacemnt will have 1 thing replaced (single) and double replacement will have 2 things replaced (double).
Hope this helps!
in a test trial, using 6% extra strength bleach at room temperature, 100.0 mL of oxygen gas was produced in 2.03 seconds. Calculate the average reaction rate for the oxygen gas.
The average reaction rate for oxygen gas is 49.26 mL/s
The average reaction rate of a substance refers to the speed at which a reaction occurs and therefore products are formed. In the reaction presented, oxygen gas is the product.
Moreover, the average reaction rate can be expressed in mL per second or mL/s, and the formula to calculate it is:
Product in mL/seconds
Let's calculate the reaction rate:
100 mL/ 2.03 s = 49.26 mL/sLearn more about oxygen in: https://brainly.com/question/1506082
A 2.50-mL aliquot of a solution that contains 6.4 ppm iron(III) is treated with an appropriate excess of KSCN to form the Fe(SCN)21 complex and diluted to 50.0 mL. What is the absorbance of the resulting solution at 580 nm in a 2.50-cm cell
Answer:
In the final solution, the concentration of sucrose is 0.126 M
Explanation:
The number of moles of solute in the volume taken from the more concentrated solution will be equal to the number of moles of solute in the diluted solution. Then, the concentration of the first solution can be calculated using the following equation:
Ci · Vi = Cf · Vf
Where:
Ci = concentration of the original solution
Vi = volume of the solution taken to prepare the more diluted solution.
Cf = concentration of the more diluted solution.
Vf = volume of the more diluted solution.
For the first dillution:
26.6 ml · 2.50 M = 50.0 ml · Cf
Cf = 26.6 ml · 2.50 M / 50.0 ml
Cf = 1.33 M
For the second dilution:
16.0 ml · 1.33 M = 45.0 ml · Cf
Cf = 16.0 ml · 1.33 M / 45.0 ml
Cf = 0.473 M
For the third dilution:
20.0 ml · 0.473 M = 75.0 ml · Cf
Cf = 20.0 ml · 0.473 M / 75.0 ml
Cf = 0.126 M
In the final solution, the concentration of sucrose is 0.126 M
hope that help
hope you have a great Christmas
mark me brinilylist
How many atoms are AI(OH)3 ?
Answer:
It has a total of three elements and seven atoms. Another use that aluminum hydroxide has is it treats the symptoms of too much stomach acid. Some examples of what it treats are: upset stomach, heartburn, and acid indigestion.
Explanation:
Atomicity is the no of atoms present in one molecule. Atomicity of Al(OH)3 = 7.
What test was used to identify hydrogen gas? Write a balanced equation to represent the test?
what happens if we mix vitamin c and d together
we can get rid of scurvy as well as rickets ......
What is the daughter nucleus of pt-199 after a beta decay?
A. At-198
B.At-200
C.Pt-200
D.At-199
B. At-200
In beta decay the atomic number increases by 1
Define atomic numbers and mass numbers
Answer:
1). Atoms of each element contain a characteristic number of protons. In fact, the number of protons determines what atom we are looking at (e.g., all atoms with six protons are carbon atoms); the number of protons in an atom is called the atomic number.
2) In contrast, the number of neutrons for a given element can vary. Forms of the same atom that differ only in their number of neutrons are called isotopes.
3) Together, the number of protons and the number of neutrons determine an element’s mass number: mass number = protons + neutrons. If you want to calculate how many neutrons an atom has, you can simply subtract the number of protons, or atomic number, from the mass number.
PLEASE HELP ME!! sue tomorrow:(
Answer:
If you are looking for the answer, for the question.
Earthquakes trigger tsunamis when the seismic activity causes the land along fault lines to move up or down
An earthquake's____
located directly above its_____
Answer:
An earthquake's what happens when two blocks of the earth suddenly slip past one another.
located directly above its The epic Center
Explanation:
Hope this helps you !!Which phenomena does wind cause?
A)tides and waves
B)deep currents and tides
C)waves and surface currents
D)surface currents and deep currents
HELP PLEASE ILL GIVE OUT BRAINLIEST
The phenomena which wind causes are waves and surface currents.
What are surface currents?
Surface currents are caused by winds which blow over the ocean water and result in creation of waves. Surface currents are horizontal streams of water which are capable of flowing thousands of kilometers and can reach great depths.
Surface currents play a major role in determining the climate all over the world. They are influenced by three major factors 1) overall global wind patterns 2)rotation of earth 3)shape of ocean basins . When a surface current collides with the land it changes the direction of currents.
Because of surface currents the global climate has warmer water from equator to the cooler parts of the ocean as they transfer heat energy.
Learn more about surface currents,here:
https://brainly.com/question/1255202
#SPJ2
How many moles is 7.78 x 1024
formula units of MgCl2?
How many moles is 7.78 x 1024
formula units of MgCl2?
answer: 7966.72
Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, there are 0.49moles of MgCl[tex]_2[/tex] in 7.78 x 10²⁴atoms of MgCl[tex]_2[/tex] .
What is mole?The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity of amount of substance. It measure the number of elementary entities of a given substance that are present in a given sample. There are so many formula for calculating mole.
we know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number
mole =given number of atoms ÷ 6.022×10²³(Avogadro number)
given number of atoms of MgCl[tex]_2[/tex]= 7.78 x 10²⁴
Substituting the values
mole= 7.78 x 10²⁴÷ 6.022×10²³
mole = 0.49moles of MgCl[tex]_2[/tex]
So, there are 0.49moles of MgCl[tex]_2[/tex] in 7.78 x 10²⁴atoms of MgCl[tex]_2[/tex] .
To know more about mole, here:
https://brainly.com/question/15209553
#SPJ2
An hibernating bear accumulates 25 kg of a triglyceride (846 g/mol) comprising the following fatty acids: C16, C17 and C18∆9. How many grams of β-hydroxybutyrate (104 g/mol) can the bear produce from this triglyceride during its hibernation?
The quantity of β-hydroxybutyrate the bear can produce
during hibernation is 3,073.30grams.
Hibernation is defined as the period of less activity by animals to conserve energy to survive coarse weather conditions.
A typical example of an animal that hibernates is the bear.
From the question, a bear is able to accumulate 25kg (25000grams) of triglyceride.
To calculate quantity of β-hydroxybutyrate that would be produced from 25kg triglyceride;
846g of triglyceride = 104grams of β-hydroxybutyrate
25000g of triglyceride = x grams
(Cross multiple to solve for x grams)
X = 104 × 25000/846
[tex]x = \frac{104 \times 25000}{846} [/tex]
[tex]x = \frac{2600000}{846} [/tex]
[tex]x = 3073.30grams[/tex]
Therefore, the quantity of β-hydroxybutyrate the bear can produce during hibernation is 3,073.30grams.
Learn more about hibernation here:
https://brainly.com/question/3047864
