From the calculations, the half life of the material is 6.5 days.
What is radioactivity?The term radioactivity has to do with the spontaneous disintegration of a specie.
Uisng the formula;
N=Noe^-kt
N= amount at time t = 0.135 Ci or 4.995 ×10^9 Bq
No = amount initially present = 1.75 x 10^12 Bq
k = rate constant = ?
t = time taken = 55 days
Hence;
4.995 ×10^9 = 1.75 x 10^12e^-55k
4.995 ×10^9/1.75 x 10^12 = e^-55k
2.85 * 10^-3 = e^-55k
ln2.85 * 10^-3 = -55k
k = ln2.85 * 10^-3/-55
k = 0.1066 day-1
Half life = 0.693/ 0.1066 day-1
= 6.5 days
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Give the postional isomers of 2 halopropane
(CH3)2CH
Give the positional isomers of 2 halopropane
(CH3)2CH
answer:
is in file download it
Balance the equation by inserting coefficients as needed. equation: C 2 H 6 O+O 2 longrightarrow CO 2 +H 2 O
The coefficients needed to balance the equation would be 2, 7, 4, and 6 respectively.
Balancing chemical equationThis requires that the number of atoms of each element is the same both on the reactant and product's sides.
Hence, the balanced equation of the reaction becomes:
[tex]2C_2 H_6 O+ 7O_2 --- > 4CO_2 +6H_2 O[/tex]
Thus, the coefficient for each species would be 2, 7, 4, and 6 respectively.
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1. Write an unbalanced equation to represent each of the following equations. (Make sure to
show diatomic elements.)
(a) iron and sulfur react to form iron(II) sulfide
(b) hydrogen gas and oxygen gas react to form water
(c) aluminum oxide reacts to form aluminum and oxygen gas
(d) zinc and copper(II) sulfate react to form zinc(II) sulfate and copper
(e) potassium hydroxide and hydrogen bromide react to form potassium bromide and
water
The equation for each reaction is written according to the relevant as below.
Equations of chemical reactionsThe reaction between iron and sulfur to form iron (II) sulfide is written as:
[tex]Fe + S --- > FeS[/tex]
The reaction between hydrogen gas and oxygen gas to form water is written as:
[tex]H_2 (g) + O_2 (g) --- > H_2O (l)[/tex]
The reaction of aluminum oxide to form aluminum and oxygen gas is written as:
[tex]Al_2O_3 --- > Al + O_2[/tex]
Zinc and copper(II) sulfate react to form zinc(II) sulfate and copper as follows:
[tex]Zn+CuSO_4--- > ZnSO_4+Cu[/tex]
Potassium hydroxide and hydrogen bromide react to form potassium bromide and water as follows:
[tex]KOH + HBr --- > H_2O + KBr[/tex]
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Part E
Tsunami evacuation plans often consider the elevation of the community and its distance from the shoreline when
deciding which towns to evacuate. How could this data help in building new homes and communities along coastal areas
that are prone to tsunamis?
Answer:
make the house elevated
how many moles are in 150 grams lf NaOH
Answer:
3.75 mole
Explanation:
molecular mass of NaOH = 39.97 gm
i.e,
==>39.97 gm NaOH contains 1 mole of NaOH
==>1 gm of NaOH contains 1/39.97 mole of NaOH
==>150 gm of NaOH contains (1/39.97) *150 mole of NaOH
==>150 gm of NaOH contains 3.75 mole of NaOH.
How do the valence electrons of an atom affect chemical reactions?
Answer:
Electrons of an atom can affect chemical reactions, because electrons have a negative charge, which can introduce a form of energy.
The direction of a reflected ray will always match its:
angle of incidence.
refracted ray.
diffused angle.
None of the choices are correct.
Answer:
angle of incidence.
What most likely happens when water vapor cools?
It changes into gas.
It changes into liquid.
Its temperature increases.
Its temperature remains constant.
Answer:
hello :)
Explanation:
Water vapor in the air reaches its dew point as it cools in the air around the can, forming liquid drops of water. Condensation is the process where water vapor becomes liquid.
All light rays parallel to the optical axis of a concave mirror are:
refracted.
reflected through the focal point.
diffused.
incandescent.
Answer:
A. Refracted
Explanation:
Incident rays parallel to the optical axis are reflected from the mirror.
Which of these statements are true? Select all that apply.
The Delta.Hf for Br2(I) is 0 kJ/mol.
The Delta.Hf for He(I) is 0 kJ/mol.
The Delta.Hf for Hg(I) is 0 kJ/mol.
The Delta.Hf for Cl2(g) is 0 kJ/mol.
The Delta.Hf for N2(I) is 0 kJ/mol.
The enthalpy of formation (ΔHf) of [tex]Br_2[/tex](g) at 1.00 atm and 298 K is 0 kJ/mol. Hence, option A is correct.
What does ΔHf mean?The standard enthalpy of formation is defined as the enthalpy change for creating one mole of a compound from elements in their standard states.
The enthalpy of formation (ΔHf) of [tex]Br_2[/tex] (g) at 1.00 atm and 298 K is 0 kJ/mol.
It is because the enthalpy of formation of the molecule is only 0 in its standard state and for bromine, the standard state at 298K is the liquid state.
Hence, option A is correct.
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Answer:
A: The Δ.Hf for Br2(I) is 0 kJ/mol.
C: The Δ.Hf for Hg(I) is 0 kJ/mol.
D: The Δ.Hf for Cl2(g) is 0 kJ/mol.
Explanation:
100.0 degrees C a sample of 750mL gas is found. If the temperature of the gas is increased by 300 degrees, what will be the new volume gas
100.0 degrees Celsius = 100.0 + 273 = 373.0 K
[tex]\frac{750}{373.0}=\frac{V_{2}}{673.0} \\ \\ V_{2}=\frac{(673.0)(750)}{373.0} \approx \boxed{1350 \text{ mL}}[/tex]
The kind of
reproduction that requires two
parents is called
What’s the answer for 3 and 8 please answer as soon as Possible due tomorrow morning.
Answer:
fgrthrdfghgfgfhfdhfdh
Explanation:
fdhhfgdghhdfghdfhgfhgfgh
Which of the following is true about homogeneous mixtures?
a) They consist of two or more phases.
b) They are always liquids.
c) They have compositions that never vary.
d) They are known as solutions.
A crate holds 20 boxes of sewing supplies. Each box contains 8 spools of thread. Each spool has 250 meters of thread wrapped around it. What length of thread is contained in a crate?
Answer: 40000
Explanation:
250*8=2,000
2000*20=40000
Calculate the mass of 162 L of chlorine gas, measured at STP.
Answer:
V=162 l
Vm=22.4 mol/l
n=V/Vm=7.23 moles
n=m/M M Cl=35.4
m=n×M
m=256.01 grams
Which of the following shows the wavelengths of light that an atom gives off when an electron falls to a lower energy level?
O A. Absorption spectrum
O B. Quantum spectrum
O C. Electromagnetic spectrum
O D. Emission spectrum
The wavelengths of light that an atom gives off when an electron falls to a lower energy level corresponds to Emission spectrum , Option D is the correct answer.
What is Emission Spectrum ?
Light is absorbed or emitted when an electron jumps or falls into an energy level.
The energy of light absorbed or emitted is equal to the difference between the energy of the orbits.
Therefore , the wavelengths of light that an atom gives off when an electron falls to a lower energy level corresponds to Emission spectrum.
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Select the correct answer.
Which of the following is a physical model of the Sun?
O A.
an equation that describes the Sun's motion
OB.
a chart that lists the temperatures of different parts of the Sun
O C.
a computer program that shows how the Sun changes over time
O D. a paragraph that describes the Sun's structure
OE.
a small yellow ball that represents the Sun
What is the molality of 35 g acetone dissolved in 0.95 kg water? The molar mass of acetone is 58.1 g/mol.
The molality of 35 g acetone dissolved in 0.95 kg water is 0. 63 mol/kg
How to determine the molalityUsing the formula:
Molality = number of moles of solute÷ mass of solvent
Note that number of moles = mass divided by the molar mass
mass of acetone = 35g
Molar mass of acetone = 58. 1g/mol
Number of moles of acetone = 35÷ 58.1 = 0.602 mole
Molality of acetone = 0. 602÷ 0. 95 = 0. 63 mol/kg
Hence, the molality of acetone is 0. 63 mol/kg
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How many total atoms are there in one molecule of C145H293O168?
Answer:
606 atoms
Explanation:
Add the numbers 145 + 293 + 168
A helium balloon possesses a volume of 2500 L at a temperature of 114 °C. What volume will the balloon have if the temperature changes to 56 °C? The pressure remains constant
Given that the pressure remains constant, if the temperature of the helium balloon decreases to the given value, the volume increases to 2125.5L.
What is Charles's law?Charles's law states that "the volume occupied by a definite quantity of gas is directly proportional to its absolute temperature.
It is expressed as;
V₁/T₁ = V₂/T₂
Given the data in the question;
Initial temperature of gas T₁ = 114°C = (114+273.15)K = 387.15KInitial volume of gas V₁ = 2500LFinal temperature T₂ = 56°C = (56+273.15)K = 329.15KFinal volume V₂ = ?V₁/T₁ = V₂/T₂
V₂ = V₁T₂ / T₁
V₂ = ( 2500L × 329.15K ) / 387.15K
V₂ = 882875LK / 387.15K
V₂ = 2125.5L
Given that the pressure remains constant, if the temperature of the helium balloon decreases to the given value, the volume increases to 2125.5L.
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A neutral atom of Sodium (Na) has an atomic number of 11 and an atomic mass of 23. Therefore, Na has _________________________ protons.
Answer:
11
Explanation:
Atomic number is the number of PROTONS an element has .
select the correct answer from each drop down menu how do you the freezing point and boiling point of a solution compare with those of us pure solvent? The freezing point of the solution is ___ and the boiling point is _____ than that of its pure solvent.
Explanation:
select the correct answer from each drp down
considering the temperature vs. time graph below, how does the temperature at the beginning of a change of state
ompare with the temperature at the end of the change?
O The temperature is always lower.
O The temperature is always the same.
O The temperature is usually lower.
The temperature is usually higher.
Answer:
temp is same
Explanation:
The change of state portionsof the graph are at 2 and 4....and the temp is the same at the beginning and ends.
change of state is a constant temp process
PLEASE HELP!!!
Choose from the given list of aqueous solutions (A-D).
Solution A has [H3O+] = 3.5×10-5 M.
Solution B has [H3O+] = 3.5×10-4 M
Solution C has [OH-] = 1.3×10-10 M
Solution D has [OH-] = 6.2×10-11 M
Which solution is the least acidic?
Which solution has the highest pH?
Which solution is the most basic?
Which solution is the least basic?
Find pH of all
#A
pH=-log[H+]
pH=-log[3.5×10^{-5}]pH=-log3.5+5pH=4.4#B
pH=-log3.5+4pH=3.4#C
pOH=-log[OH]
pOH=-log[1.3×10^{-10}]pOH=-log1.3+109.8pH=
14-9.84.2#4
pOH=-log6.2+11pOH=10.2pH
14-10.23.8So our answers
solution A is least acidicsolution A has the highest pHsolution A is most basicsolution B is least basicBalance this reaction.
CO +
H2 →
CH3OH
What is the pH of a solution that has a [H+] = 0.010 mol/L?
Answer:
pH = 2
A 0.010 M solution of hydrochloric acid, HCl, has a molarity of 0.010 M. This means that [H+] = 1 x 10-2 M. The pH of this aqueous solution of H+ ions is pH = 2
hope this helps :3
answer number ! and fill in the unkown
The identity of the unknown compound is Urea from the Table# given. The reason for this identification will further be discussed below.
What is melting point?Melting point can be defined as the point at which a substance changes from a solid phase or state to a liquid state
When two substances of different melting points are added together, the total melting point obtained is usually depressed.
From the table,
When urea and benzoic acid is added the melting point range becomes = 117-120When urea and Cinnamic acid is added the melting point range becomes= 100-125, and both of which is lower than the individual melting points.Therefore, the identity of the unknown compound is Urea from the Table# given.
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20.0 g of bromic acid, HBrO3, is reacted with excess HBr.
HBrO3 (aq) + 5 HBr (aq) → 3 H2O (l) + 3 Br2 (aq)
What is the theoretical yield of Br2 for this reaction? Round your answer to the nearest gram.
After Rounding off The percentage yield is 64%
What is Percentage Yield ?It is the ratio of actual yield to theoretical yield multiplied by 100% .
It is given in the question
20.0 g of bromic acid, HBrO3, is reacted with excess HBr.
The reaction is
HBrO₃ (aq) + 5 HBr (aq) → 3 H₂O (l) + 3 Br₂ (aq)
Actual yield = 47.3 grams
Molecular weight of Bromic Acid is 128.91 gram
Moles of Bromic Acid = 20/128.91 = 0.155 mole
Mole fraction ratio of Bromic Acid to Bromine is 1 :3
Therefore for 0.155 mole of Bromic Acid 3 * 0.155 = 0.465 mole of Bromine is produced.
1 mole of Bromine = 159.8 grams of Bromine
0.465 of Bromine = 74.31 grams of Bromine
Percentage Yield = (47.3/74.31)*100 = 63.65 %
After Rounding off The percentage yield is 64% .
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Answer:
74g
Explanation:
The other person had said that the Percentage Yield = (47.3/74.31)*100 = 63.65 %
So, since to find the percent yield you have to divide the actual yield by the theoretical yield, I would assume the theoretical yield is 74.31g (74g if you round to the nearest gram)
An acid is used to bring the pH of a solution from pH 9 to pH 6. How many times more acidic is the final solution than the initial solution?
Select one:
a.
3
b.
10
c.
100
d.
1000
How many grams of Ca(OH)2 are needed to produce 500 ml of 1.66 M Ca(OH)2 solution?
61.5 grams of Ca(OH)2 are needed to produce 500 ml of 1.66 M Ca(OH)2 solution. Details about mass can be found below.
How to calculate mass?The mass of a substance can be calculated by multiplying the number
of moles of the substance by its molar mass.
However, in this question, the number of moles in 500 ml of 1.66 M Ca(OH)2 solution must be calculated first.
no of moles = 1.66M × 0.5L
no of moles = 0.83moles
molar mass of Ca(OH)2 = 74.093 g/mol
mass of Ca(OH)2 = 74.093 × 0.83 = 61.5g
Therefore, 61.5 grams of Ca(OH)2 are needed to produce 500 ml of 1.66 M Ca(OH)2 solution.
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