What fraction of a 100 g sample of K - 42 will remain after 24.8 hours?
Answer:
1/4
Explanation:
From the question given above, the following data were:
Original amount (N₀) = 100 g
Time (t) = 24.8 h
Fraction remaining =?
NOTE: The half-life of K–42 is 12.4 h
Next, we shall determine the number of half-lives that has elapse. This can be obtained as follow:
Time (t) = 24.8 h
Half-life (t½) = 12.4 h
Number of half-lives (n) =?
n = t / t½
n = 24.8 / 12.4
n = 2
Finally, we shall determine the fraction remaining. This can be obtained as follow:
Number of half-lives (n) = 2
Fraction remaining =?
Fraction remaining = 1/2ⁿ
Fraction remaining = 1/2²
Fraction remaining = 1/4
What is the energy change when a 777.1 g sample of water has
an initial temperature of 57.3 °C and a final temperature of
42.6 °C
Answer:
-47749.69 joule energy release.
Explanation:
Given data:
Mass of water = 777.1 g
Initial temperature = 57.3°C
Final temperature = 42.6 °C
Energy change = ?
Solution:
Specific heat capacity of water is 4.18 J/g.°C
Q = m.c. ΔT
Q = amount of heat absorbed or released
m = mass of given substance
c = specific heat capacity of substance
ΔT = change in temperature
ΔT = 42.6 °C - 57.3°C
ΔT = -14.7°C
Q = 777.1 g × 4.18J/g.°C × -14.7°C
Q = -47749.69 J
-47749.69 joule energy release.
(3)
Calculate the entropy change when a sample of argon at 25 °C and 1.00 atm in a container
of volume 500 cm3 is compressed to 50 cm3 and cooled to -25 °C.
For argon, Cpm = 20.786) K-Imol-1. Assume that argon behaves perfectly.
Answer:
[tex]\Delta s=-23.0\frac{J}{mol*K}[/tex]
Explanation:
Hello!
In this case, since the entropy change when an ideal gas undergo both a volume and temperature change is computed by:
[tex]\Delta s =Cp*ln(\frac{T_2}{T_1} )-R*ln(\frac{P_2}{P_1} )[/tex]
Whereas the molar Cp is 20.786 J/(mol*K) and the final pressure is computed via the Boyle's law:
[tex]P_2=\frac{1.00atm*500cm^3}{50cm^3}=10 atm[/tex]
Thus, we plug in the data (temperatures in Kelvin) to obtain:
[tex]\Delta s =20.786\frac{J}{mol*K} *ln[\frac{(-25+273)K}{(25+273)K} ]-8.3145\frac{J}{mol*K}*ln(\frac{10atm}{1atm} )\\\\\Delta s=-23.0\frac{J}{mol*K}[/tex]
Best regards!
When relative humidity is at 100 percent, air is said to be what?
Answer:
Fully saturated or "a chance of rain"
Explanation:
When relative humidity reaches 100%, the air is fully saturated with vapor. That means that there is a possibility of rain.
PLEASEEEE PLEASE HELP MEEEE... i begg you
Answer:
the answer to the first one is B and the second one is that the volume is a control, the heart rates are dependent, the how music played is controlled, how the heart rates are measured is controlled, the music played is independent
PLEASE HELP
What do you know about valence electrons?
Answer:
Valence electrons are the electrons in the outermost shell, or energy level, of an atom
Explanation:
Answer:
Valence electrons are the electrons in the outermost shell, or energy level, of an atom. For example, oxygen has six valence electrons, two in the 2s subshell and four in the 2p subshell. We can write the configuration of oxygen's valence electrons as 2s²2p⁴
Is Na2SO4 ionic or covalent
Answer: What types of bonds exist between the atoms in a molecule of sodium sulfate, Na2SO4 ? The formula for this compound can be written as [Na+]2[SO42-], the sulfate anion is formed by covalent bonding between sulfur and oxygen. Since there is a bond polarity to a S-O bond these are polar covalent bonds.
Explanation:
The sulphate anion is created via covalent interaction between oxygen and sulphur, and the formula to this chemical is [[tex]Na^+[/tex]][[tex]SO_4^{2-}[/tex]]. These S-O bonds constitute polar covalent bonds because they have a bond polarity.
A polar bond represents a particular type of covalent bond in general. It is also the point at which an ionic bond and an unadulterated covalent bond begin to form, according to another definition. A polar covalent bond, on the other hand, is a link that occurs between two atoms and is made up of electrons which are scattered unevenly if we would like to explain it more precisely. The molecules have a tendency to have an electrical dipole moment in which the two ends are slightly either positive or negative as a result of this condition. The sulphate anion is created via covalent interaction between oxygen and sulphur, and the formula to this chemical is [[tex]Na^+[/tex]][[tex]SO_4^{2-}[/tex]]. These S-O bonds constitute polar covalent bonds because they have a bond polarity.
To know more about polar covalent bond, here:
https://brainly.com/question/28295508
#SPJ6
Which of the following describes a perpetual-motion machine?
A. A battery that contains one oxidized metal and one reduced metal
B. A renewable energy source
C. A motor that requires no energy input once it is running
D. An electric motor that is powered by an electromagnet
SUBMIT
Answer:
a motor that requires no energy input once it is running
Answer:
c
Explanation:
a p e x :)
How many moles are in 17.0 grams of H2O2?
Answer: 0.500
Explanation:17.0 g H202 x (1 mol H202/34.0 g H202)=0.500 mol H202
Answer: 0.5 moles are present in 17.0 g of [tex]H_{2}O_{2}[/tex] .
Explanation:
Number of moles present in a substance is the given mass divided by molar mass of the substance.
As the given mass of [tex]H_{2}O_{2}[/tex] is 17.0 g and its molar mass is 34 g/mol.
Hence, number of moles present in given 17.0 g of [tex]H_{2}O_{2}[/tex] is as follows.
No. of moles = [tex]\frac{mass}{molar mass}[/tex]
= [tex]\frac{17.0 g}{34 g/mol}[/tex]
= 0.5 moles
Therefore, 0.5 moles are present in 17.0 g of [tex]H_{2}O_{2}[/tex] .
How many grams are in 0.75 moles of zinc?
Answer:
There are 65.38 grams are in 0.75 moles of zinc?
explain :We assume you are converting between moles Zinc and gram. You can view more details on each measurement unit: molecular weight of Zinc or grams The molecular formula for Zinc is Zn. The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles Zinc, or 65.38 grams.
I hope it will be helpful for youin an electron dot diagram of fluorine , how many dots should be drawn around the elements symbol
Answer:
7 dots
Explanation:
What is the first step for response to an emergency situation?
Answer:
Back away from the situation and tell the supervisor/teacher
The density of whole milk 1.04 g per mL. What is the volume (in quarts) of 18.5 pounds of whole milk?
The volume : 8,526 quarts
Further explanationGiven
The density of whole milk = 1.04 g/ml
mass = 18.5 pounds
Required
The volume
Solution
Conversion of mass
1 pound = 453,592 g
18.5 pounds = 8391,45 g
Density formula:
[tex]\large{\boxed {\bold {\rho~=~ \frac {m} {V}}}}[/tex].
Input the value :
V = m : ρ
V = 8391,45 g : 1.04 g/ml
V = 8068.7 ml
1 ml = 0,00105669 quarts
8068.7 ml =8,526 quarts
HELP ASAP! I will give brainiest if you answer all questions correctly.
28) Choose the best answer.
Calculate the amount of heat required or released. You will need to use your Periodic Table, Table B-3 and Table B-4, in your Chemistry Reference Guide.
How much heat is required to raise the temperature of 155 g of liquid ammonia (NH3) at 200 K to ammonia gas at 300 K? Ammonia boils at 240 K.
261 kJ
-204kJ
209kJ
-88kJ
300 kJ
29) Choose the best answer.
Calculate the amount of heat required or released. You will need to use your Periodic Table, Table B-3 and Table B-4, in your Chemistry Reference Guide.
How much heat would be needed to raise the temperature of 255 grams of ice at 253 K to steam at 393 K?
-204kJ
300 kJ
209kJ
-88kJ
788 kJ
30) Choose the best answer.
Calculate the amount of heat required or released. You will need to use your Periodic Table, Table B-3, Table B-4, and Table B-5 in your Chemistry Reference Guide.
How much heat is lost when 2012 g of H2O at 400 K is changed into ice at 263 K?
300 kJ
-880 kJ
299 kJ
-204 kJ
-6201 kJ
Answer:
28). 261
29). 788
30).-6201
Explanation:
I just took lesson and it said those were correct, I added screenshots of the lesson if you need it :)
What's the equation for the reaction of Trifluoro bromide with Ammonia gas. ( brainliest assured )
Answer:
Ammonium bromide can be prepared by the direct action of hydrogen bromide on ammonia. It can also be prepared by the reaction of ammonia with iron(II) bromide or iron(III) bromide, which may be obtained by passing aqueous bromine solution over iron filings.
Explanation:
please mark me as brainliest thank you
) The volume of a balloon was 50,200 litres. If the temperature
at ground level was 25 degree celcius and the atmospheric pressure was
720mm Hg. How many moles of Hydrogen gas were needed to
fill the balloon?
Answer:
1943.1 moles
Explanation:
From the question given above, the following data were obtained:
Volume (V) = 50200 L
Temperature (T) = 25 °C
Pressure (P) = 720 mmHg
Number of mole (n) of H₂ =?
Next, we shall convert 25 °C to Kelvin temperature. This can be obtained as follow:
T(K) = T(°C) + 273
Temperature (T) = 25 °C
Temperature (T) = 25 °C + 273
Temperature (T) = 298 K
Next, we shall convert 720 mmHg to atm. This can be obtained as follow:
760 mmHg = 1 atm
Therefore,
720 mmHg = 720 mmHg × 1 atm / 760 mmHg
720 mmHg = 0.947 atm
Thus, 720 mmHg is equivalent to 0.947 atm
Finally, we shall determine number of mole of Hydrogen gas, H₂, needed to fill the balloon as follow:
Volume (V) = 50200 L
Temperature (T) = 298 K
Pressure (P) = 0.947 atm
Gas constant (R) = 0.0821 atm.L/Kmol
Number of mole (n) of H₂ =?
PV = nRT
0.947 × 50200 = n × 0.0821 × 298
47539.4 = n × 24.4658
Divide both side by 24.4658
n = 47539.4 / 24.4658
n = 1943.1 moles
HELP PLEASE! Which of these is an example of the climate of a region?
Continental
Foggy
Overcast
Sunny
Answer:
Continential
Explanation:
foggy, overcast, and sunny are all examples of weather
What are the three states in which water exists on Earth?
How many grams of H2 are needed to react with 2.85 g of N2?
If 2.35 L hydrogen gas react with nitrogen gas to form nitrogen trihydride, how many grams of nitrogen will be needed for the reaction to be completed?
0.98 g
0.49 g
21.93 g
1.47 g
Answer:
1.47 g
Explanation:
Which element consists of positive ions immersed in a “sea” of mobile electrons?
A.
Sulfur
B.
Nitrogen
C.
Calcium
D.
Chlorine
Answer:
Calcium
Explanation:
Calcium is the only metal here
hope this helps...
A positive ion is an atom or a molecule that has a net positive charge. The charge of the proton in an atom or a molecule is positive.
A subatomic found in the atom or the molecule that lacks a positive charge is called an electron.
The correct answer is:
Option C. Calcium
This can be explained by:
Compounds or substances which have positive ions engaged in a sea of movable electrons are assumed to be metals.The electrons existing in the metals encompass the positively loaded nuclei instead of projecting their assigned atoms.Calcium is the only metal found in the given list and hence is the answer.
To learn more about electrons, protons and metals follow the link:
https://brainly.com/question/21940587
In the equation:
X →
226
88
Ra + He
The symbol Xrepresents
A)
222
Th
86
222
B)
Rn
86
230 Th
C)
90
D)
230
90
Rn
Answer:
²³⁰₉₀Th
Explanation:
X → ²²⁶₈₈Ra + ⁴₂He
The given equation shows the alpha emission. When He particle emit the original atom convert into the atom having mass number less than 4 and atomic number less than 2 as compared to parent atom the starting atom. It means the parent atom is ²³⁰₉₀Th.
Alpha radiations are emitted as a result of radioactive decay. The atom emit the alpha particles consist of two proton and two neutrons. Which is also called helium nuclei. When atom undergoes the alpha emission the original atom convert into the atom having mass number less than 4 and atomic number less than 2 as compared to parent atom the starting atom.
Alpha radiations can travel in a short distance.
These radiations can not penetrate into the skin or clothes.
These radiations can be harmful for the human if these are inhaled.
These radiations can be stopped by a piece of paper.
₉₂U²³⁸ → ₉₀Th²³⁴ + ₂He⁴ + energy
are all elements created equal? Provide evidence for why or why not.
A compound is found to contain 25.24 % sulfur and 74.76 % fluorine by weight. The molecular weight for this compound is 254.14 g/mol. What is the molecular formula for this compound
Answer:
[tex]S_2F_{10}[/tex]
Explanation:
Hello!
In this case, since the empirical formula of a chemical compound is determined by assuming the by-mass percentages are masses, we can firstly compute the moles of sulfur and fluorine based on their atomic masses:
[tex]n_S=25.24gS*\frac{1molS}{32.01gS}=0.789molS\\\\n_F=74.76gF*\frac{1molF}{19.00gF}=3.93molF[/tex]
Next, we compute the subscript of each element in the formula by dividing each moles by the fewest moles:
[tex]S=\frac{0.789}{0.789}=1\\\\F=\frac{3.93}{0.789} =5[/tex]
Whose molar mass is 127.01 g/mol. Now, we can compute the ratio between the molecular and empirical formulas as follows:
[tex]ratio=\frac{254.14}{127.01} =2[/tex]
Thus, the molecular formula is:
[tex]S_2F_{10}[/tex]
Regards!
A blueberry bush uses energy from the sun to make sugars. which set of enerdy transformations BEST describe this process?
Why are salt solutions not used to treat the roads during snow events when the temperature is below -15 degrees Celsius? *
A. Salts are nonelectrolytes and do not demonstrate the Van't Hoff Factor.
Therefore the freezing point cannot be depressed lower than -15 C.
B.The solubility of a salt will decrease with decreasing temperature making it even more difficult to concentrate a solution. The maximum quantity that can saturate a solution and attain the maximum molality that aligns with solubility values at that low of a temperature cannot provide the multiplier high enough to depress the freezing point to temperatures below -15 C.
C.Salt has a maximum molality of 0.6m.
D.Salts can melt ice but cannot prevent freezing.
Answer:
i think thats c
Explanation:
2210.20 J of energy is equal to how many calories?
Answer:
528.25 Calories
Explanation:
From the question given above, the following data were obtained:
Energy in Joules = 2210.20 J
Energy in calories =?
We can convert 2210.20 J to calories by doing the following:
4.184 J = 1 cal
Therefore,
2210.20 J = 2210.20 J × 1 cal / 4.184 J
2210.20 J = 528.25 Calories
Thus, 2210.20 J is equivalent to 528.25 Calories.
A neutral atom has the following electronic configuration: 1s2 2s2 2p6 3s2 3p5
How many protons are in the atomic nucleus and to which group of the periodic table does this element belong?
Answer:
Number of protons=17
Halogen
Explanation:
Given,
The electronic configuration:[tex]1s^2, 2s^2, 2p^6, 3 s^2, 3 p^5[/tex]
Atomic number= 2+2+6+2+5 = 17
Chlorine has the atomic number 17.
Symbol of chlorine= Cl
We know that,
The number of protons is equal to the atomic number.
Number of protons=17
And Chlorine belongs to the halogen group of the periodic table.
Question (2) If your car
gets 27.8 miles to the gallon, how many liters of gasoline are necessary to travel 112 km?
This problem can be solved in short steps or in one longer step. In either case, please show your work.
Use the following conversion factors:
1 mi = 1.609 km
1 gal = 3.785 L
Answer:
9.48 L.
Explanation:
Hello!
In this case, as the problem mentions a long way to solve it, we are going to apply it because it can provide the answer more rapidly; thus, considering that 112 km are required, 1 mile equals 1.609 km and 1 gallon equals 3.785 liters, we can set up the proportional factor as shown below:
[tex]112km*\frac{1mi}{1.609 km}*\frac{1gal}{27.8mi}*\frac{3.785L}{1gal}[/tex]
Whereas km, mi and gal are cancelled out as it turns out in L; therefore the required liters are:
[tex]9.48L[/tex]
Best regards!
snow and ice absorbs much of the Sun's radiant energy
True or False?
Answer with "True" Or "False" please, thank you.
Answer: True
Explanation: I have done this before but I hope this helps.