Answer:
Option C. 24 days / 4 grams
Explanation:
From the question given above, the following data were obtained:
Days Elapsed >>>> Mass Remaining
0 >>>>>>>>>>>>>>> 16
12 >>>>>>>>>>>>>>> 11
24 >>>>>>>>>>>>>>> 8
36 >>>>>>>>>>>>>>> 6
A. Determination of the half-life of Thorium-234.
To determine the half-life, it is important to know the definition of half life.
Half-life is defined as the time taken for a substance to reduce to half its original mass.
From the table given above, we can see that the original mass of the isotope is 16 g (i.e at 0 day). By day 24, the mass of the isotope is 8 g (i.e half the original mass). Thus, the half-life of the isotope is 24 days.
B. Determination of the mass of the isotope remaining after 2 half lives.
Original amount (N₀) = 16 g
Number of half-lives (n) = 2
Amount remaining (N) =?
N = 1/2ⁿ × N₀
N = 1/2² × 16
N = 1/4 × 16
N = 4 g
Thus, 4 g of the isotope is remaining after 2 half lives.
Summay:
Half-life = 24 days
Amount remaining after 2 half-lives = 4 g
Option C gives the correct answer to the question.
Analysis of a salt results in the following composition: 3.47 g of Sodium; 2.12 g of Nitrogen; and 7.27 g of Oxygen. What is the simplest formula for this salt
Answer:
NaNO₃
Explanation:
Data obtained from the question include:
Mass of sodium (Na) = 3.47 g
Mass of nitrogen (N) = 2.12 g
Mass of oxygen (O) = 7.27 g
Simplest (empirical) formula =?
The simplest formula for the salt can be obtained as follow:
Na = 3.47 g
N = 2.12 g
O = 7.27 g
Divide by their molar mass
Na = 3.47 / 23 = 0.151
N = 2.12 / 14 = 0.151
O = 7.27 / 16 = 0.454
Divide by the smallest
Na = 0.151 / 0.151 = 1
N = 0.151 / 0.151 = 1
O = 0.454 / 0.151 = 3
Simplest formula = NaNO₃
Thus, the simplest formula for the salt is NaNO₃
can u pls help me with this question
Answer:
it's mass
Explanation:
just trust me it's just mass
So its not A so its B C or D plz help
Answer:
the answer is B
hope this helped!
Triangle K L J. Side K L is 23.1 feet, J L is 20.1 feet, J K is 16.8 feet. Angle K is 58 degrees, L is 45 degrees, J is 77 degrees. Triangle E F G. Side E F is 6.7 feet, F G is 5.6 feet, G E is blank. Angle E is 45 degrees, F is 77 degrees, G is 58 degrees.
Given these similar triangles, what is the common ratio of triangle LJK to triangle EFG?
1.5
2
3
4
the answer is 3
"C"
Answer:
The answer is C or 3
Explanation:
I took the assignment
Answer:
3 or C on edge
Explanation:
WILL GIVE BRAINLEST PLZZZZ
Question 1 (2 points)
The highest point of a wave is called the
Question 1 options:
Wavelength
Crest
Trough
Top
Question 2 (2 points)
Which statement BEST explains why the Moon is visible from the Earth?
Question 2 options:
The Moon reflects light from the Earth.
The Moon reflects light from the Sun.
The Moon produces its own light through radiation.
The Moon is always lit up by the Sun for us to see.
Question 3 (2 points)
Which of these is NOT a factor that is considered when describing the climate of a region?
Question 3 options:
The population of the region
The number of mountains nearby
The amount of precipitation
Distance from the ocean
Question 4 (2 points)
Which planets are small, dense, and have a rocky outer surface?
Question 4 options:
All Planets
Inner Planets
Gas Giants
Outer Planets
Question 5 (2 points)
Which of the following is an example of a climate region?
Question 5 options:
Tropical
Snowy
Rainy
Sunny
Question 6 (2 points)
Which of the following is the LEAST LIKELY to directly affect a location's weather?
Question 6 options:
Air Pressure
Pollution
Air Temperature
Cloud Cover
Question 7 (2 points)
When people on the Earth cannot see the Moon, which phase is it in?
Question 7 options:
Full Moon
Waning Crescent
New Moon
Waxing Gibbous
Question 8 (2 points)
If you were testing how effective different dish soaps were at cleaning grease off of dishes, the dependent variable would be the:
Question 8 options:
types of grease
cleanliness of washed dishes
different dish soaps
temperature of the wash water
Question 9 (2 points)
Which of the following is NOT true about comparisons between analog and digital signals?
Question 9 options:
Digital signals are more prone to distortion.
Analog signals are used to convert sound waves into electronic signals.
Digital signals are pulses of voltage that switch currents on an off in devices like computers.
Analog signals are more prone to distortion.
Question 10 (2 points)
Which of the following statements best describes what will happen when white light hits a red object?
Question 10 options:
All wavelengths of the light are reflected.
Red wavelengths are reflected while all others are absorbed.
All wavelengths of the light are absorbed.
Red wavelengths are absorbed while all others are reflected.
Question 11 (2 points)
Long hair in the laboratory must be
Question 11 options:
cut short
held away from the experiment with one hand
always neatly groomed
tied back
Question 12 (2 points)
When the Moon is positioned so that the entire lit half is facing AWAY from the Earth it is in which phase?
Question 12 options:
Full Moon
New Moon
Waxing Gibbous
Waning Crescent
Question 13 (2 points)
The lowest part of a wave is called the
Question 13 options:
Wavelength
Lowpoint
Crest
Trough
Question 14 (2 points)
Which statement best describes how the Sun and the planets are related?
Question 14 options:
The planets revolve around the Sun.
The Sun rotates on its axis.
The Sun revolves around the planets.
Planets rotate on their axes.
Question 15 (2 points)
The number of light waves that occur in one second is known as the wave's
Question 15 options:
energy
movement
frequency
amplitude
Answer:
Explanation:
This is what I would answer and I might be wrong***
1. Crest
2. The Moon reflects light from the Sun
3. Population of the region
4. Inner Planets
5. Tropical
6. Pollution (I am not 100% but it would make sense because pollution is long term consequences)
7. New Moon
8. Cleanliness of washed dishes
9. Analog signals are more prone to distortion.
10. Red wavelength are reflected while all others are absorbed
11. Tied back (I would assume)
12. New Moon (I think)
13. Trough
14. The planets revolve around the Sun
15. Frequency
16. Decreases
17. furthest; least
18. ? sry I don't get what the question is trying to ask.
19. wavelength
20. independent; dependent
21. Sun; Earth
Answer:
1) Crest
2)D
3) distance from ocean
4) outer planets
5)tropical
6)air pressure
7)new moon
8)Temp of water
9)C i think
10)B
(still finding answers)
Explanation:
When an animal eats corn or peanuts, will it also eat the seeds?
Answer:yes
Explanation:it doesnt know
What is the percent composition of oxygen in
beryllium nitrate, Be(NO3)2?
The percent composition of oxygen in beryllium nitrate, Be(NO3)2 is 72.166%.
What is percent composition ?
Percent composition is very straightforward. Percent composition indicates the percentage of each element in a compound by mass. A chemical compound is made up of two or more elements.
Percent composition is important because it allows us to calculate the percentage of each element in a compound. Here, the quantity is measured in terms of grams of the elements present.
For example, if we know the mass and chemical composition of a substance, we can find out the number of moles and calculate the number of atoms or molecules in the sample.
In Be(NO3)2 the percent composition of Beryllium (Be) is 6.775%, Nitrogenium (N) is 21.060% and Oxygenium (O) is72.166%.
Thus, The percent composition of oxygen in beryllium nitrate, Be(NO3)2 is 72.166%.
To learn more about the percent composition, follow the link;
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#SPJ6
1s2 2s2 2p6 3s2 3p6 4s2 3d 10 4p6 5s2 4d7 element electron configuration?
Answer:
antimony
Explanation:
The representation of the electrons in the shell is called electronic configuration.
The correct answer is antimony
The shell is as follows:-
SPDFThese are the shells in which electrons are filled.
The total number of electrons is 2+2+6+2+6+2+10+6+2+7= 45
After calculating the electrons, the total number of electrons is 45 which is the atomic number of antimony.
Hence, antimony is the correct option.
For more information, refer to the link:-
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? January 5/6. What can you do differently for
the last half of the year in science? Whether it is
improving study skills, turning work in on time,
etc
Answer:
Explanation:
I'd say art
A chemist must dilute 97.1 ml of aqueous magnesium fluoride solution until the concentration falls to 389 microMolarity . He'll do this by adding distilled water to the solution until it reaches a certain final volume. Calculate this final volume, in liters. Round your answer to significant digits.
Answer:
0.302L
Explanation:
...97.1mL of 1.21m M aqueous magnesium fluoride solution
In this problem the chemist is disolving a solution from 1.21mM = 1.21x10⁻³M, to 389μM = 389x10⁻⁶M. That means the solution must be diluted:
1.21x10⁻³M / 389x10⁻⁶M = 3.11 times
As the initial volume of the original concentration is 97.1mL, the final volume must be:
97.1mL * 3.11 = 302.0mL =
0.302L
There are three isotopes of X element (X):
X-17 isotope: atomic mass17.2 amu, abundance:78.99%
X-18isotope: atomic mass 18.1 amu, abundance 10.00%
X-19isotope: atomic mass:19.1 amu, abundance: 11.01%
Calculate the average atomic mass of X.
Answer:
Average atomic mass = 17.5 amu.
Explanation:
Given data:
X-17 isotope = atomic mass17.2 amu, abundance:78.99%
X-18isotope = atomic mass 18.1 amu, abundance 10.00%
X-19isotope = atomic mass:19.1 amu, abundance: 11.01%
Average atomic mass of X = ?
Solution:
Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) + (abundance of 3rd isotope × its atomic mass) / 100
Average atomic mass = (78.99×17.2)+(10.00×18.1) +(11.01+ 19.1) /100
Average atomic mass = 1358.628 + 181 +210.291 / 100
Average atomic mass = 1749.919 / 100
Average atomic mass = 17.5 amu.
pleaseeee help me asap
Answer : i think the answer is A
Explaination : its not D , C i feel like it would be bigger so there would be more transpiration an B less would not have bigger so i hope this helps have a good day ☆
What technology allowed scientists to collect new data on layers of the earth
Question 4 (1 point)
60.5 mL of 0.223 M HI is mixed with 86.0 mL of a buffer system composed of 0.385 M sodium acetate and 0.410 M acetic acid. Find the pH of
the final solution
Ko of acetic acid = 1.8 E-5
4561
o a
Ob
Ос
Od
4.673
4.450
4.349
Answer:
pH = 4.349
Explanation:
When HI is added to sodium acetate, CH3COONa, acetic acid is produced as follows:
CH3COONa + HI → CH3COOH + NaI
That means the moles of HI added are the moles of acetic acid produced and the moles of sodium acetate consumed.
Moles of HI:
0.0605L * (0.223mol/L) = 0.01349mol
To find pH of the buffer (Mixture of weak acid, acetic acid, and conjugate base, sodium acetate) we need to solve H-H euation:
pH = pKa + log [CH3COONa] / [CH3COOH]
Where pKa is -log of Ka of the acid: -log1.8x10⁻⁵ = 4.745
And [] could be taken as moles of each specie
Moles CH3COONa:
Inital moles: 0.086L * (0.385mol/L) = 0.03311
Final moles: 0.03311mol - 0.01349mol = 0.01962mol CH3COONa
Moles CH3COOH:
Inital moles: 0.086L * (0.410mol/L) = 0.03256
Final moles: 0.03256mol + 0.01349mol = 0.04875mol CH3COOH
pH = 4.745+ log [0.01962mol CH3COONa] / [0.04875mol CH3COOH]
pH = 4.3497
Rigth answer is:
4.349
A landscape in Antarctica has an area of 500,000 square miles. It is covered with ice, giving the landscape an average elevation of 7520 feet. Without the ice, it is estimated the landscape would have an average elevation of 1500 ft. The average density of the ice is 0.917 g/mL. How many tonnes of ice cover that landscape?
Answer:
m = 2.18x10¹⁵ tons of ice
Explanation:
To solve this exercise, we need to work with the same units of conversion. In this case let's see the conversion of every unit here:
1 mi = 5280 ft
1 ton = 1000 kg
1 kg = 1000 g
1 mL = 1 cm³
1 mi = 1609.34 m or 160,934 cm
Now that we know the units, let's analyze the data.
The landscape has a 500,000 mi² of area, this is however without including the ice. The ice is apart, and has a 7520 ft of height. And if the landscape wouldn't have ice, then the height will be 1500 ft only.
With that data, we can know the actual height of the ice by a simple difference:
Hi = Hli - Hl
Where:
Hi: Height of ice
Hli: Height of ice + landscape
Hl: Height of landscape
Applying this expression, the height of ice is:
Hi = 7520 - 1500 = 6020 ft of ice
Now that we know the height of the ice, we can calculate the volume of whole landscape. But first, let's do the conversion of foot to mile:
Hi = 6020 ft * (1 mi/5280 ft) = 1.14 mi
And now, let's calculate the volume of the landscape in mile, and then, to centimeter:
V = 1.14 mi * 500,000 mi² = 570,000 mi³
To convert the cubic mile to cubic centimeter we just do the following:
V = 570,000 mi³ * (160934 cm / 1 mi)³ = 2.38x10²¹ cm³
Now, we can get the mass of the ice using the given density of ice (d = 0.917 g/cm³)
If d = m/V
then m = d * V
Replacing the data:
m = 0.917 g/cm³ * 2.38x10²¹ cm³
m = 2.18x10²¹ g
Finally, the tons of ice will be:
m = 2.18x10²¹ g * (1 kg / 1000 g) * (1 ton / 1000 kg)
m = 2.18x10¹⁵ tons of iceHope this helps
Which atom has multiple oxidation states and
forms an ion that is colored when in solution?
A) F
B) Zn
C) C1
D) Cu
Answer:
Copper
Explanation:
Which of the following is most likely to produce heat energy?
A
Momentum
B
Convection
C
Interaction
D
Magnetism
Answer:
B.Convection
the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat.
Answer:
B.
Explanation:
Write as a single exponent in simplest form: y⁸×y⁵
Answer:
y¹³
Explanation:
because it's a multiplication question we add exponents
8 + 5 = 13
so it's y¹³
The table compares the final cost of
groceries after a coupon is used.
Cost Before
Coupon (a)
$20
$21
$22
$23
Cost After
Coupon (b)
$17.50
$18.50
$19.50
$20.50
Which equation models the relationship?
Answer:
y = -2.5 + x
Explanation:
Given the data:
__X____Y
$20 __$17.50
$21 __ $18.50
$22__ $19.50
$23__ $20.50
Using a linear regression calculator :
The linear regression model obtained is :
y = -2.5 + x
Where ; - 2.5 = intercept ; gradient / slope = 1
What is the heat of a reaction, in joules, with a total reaction mixture volume of 73.0 mL if the reaction causes a temperature change of 4.4 oC in a calorimeter
This question is incomplete, the complete question is;
What is the heat of a reaction, in joules, with a total reaction mixture volume of 73.0 mL if the reaction causes a temperature change of 4.4 °C in a calorimeter?
Assume that the reaction mixture has a density of 1.00 g/mL and a specific heat of 4.184 J/g-oC. The calorimeter has a heat capacity of 10.0 J/oC.
Answer: the heat of the reaction is 1387.9 J
Explanation:
Given that;
Volume = 73.0 mL
density = 1.00 g/mL
specific heat of solution = 4.184 J/g-oC
calorimeter has a heat capacity of 10.0 J/oC.
Temperature change ΔT = 4.4 °C
the heat of a reaction = ?
Total heat of the reaction will be equal to the amount of heat absorbed/lost by the solution and the calorimeter.
so heat of reaction q = mC_solΔT + C_alΔT
where m is mass, C_sol is specific heat capacity of the solution, ΔT temperature change and C_cal is heat capacity of calorimeter.
so first we calculate our mass;
mass = volume × density
= 73.0 mL × 1.00 g/mL
= 73.0 g
so we substitute into our equation;
q = mC_solΔT + C_alΔT
q = (73 × 4.184 × 4.4) + ( 10 × 4.4 )
q = 1343.9008 + 44
q = 1387.9 J
Therefore the heat of a reaction is 1387.9 J
The rate law for the decomposition of phosphine () is It takes 135. s for 1.00 M to decrease to 0.250 M. How much time is required for 3.00 M to decrease to a concentration of 0.450 M
Answer:
189.71 secs
Explanation:
We know that decomposition is a first order reaction;
So;
ln[A] = ln[A]o - kt
But;
[A]o = 1.00 M
[A] = 0.250 M
t =135 s
Hence;
ln[A] - ln[A]o = kt
k = ln[A] - ln[A]o/t
k = ln(1) - ln(0.250)/135
k =0 - (-1.386)/135
k = 1.386/135
k= 0.01
So time taken now will be;
ln[A] - ln[A]o = kt
t = ln[A] - ln[A]o/k
t = ln (3) - ln(0.450)/0.01
t = 1.0986 - (-0.7985)/0.01
t = 1.0986 + 0.7985/0.01
t = 189.71 secs
Which statement best describes what happens during a chemical change?
Both the identity and the properties of a substance change.
Some properties of a substance change, but its identity remains the same.
The chemical properties of a substance change, but its physical properties rema
The physical properties of a substance change, but its chemical properties rema
Answer:
Both the identity and the properties of a substance change.
Explanation:
During most chemical reactions, both the identity and the properties of substances changes. The chemical and physical properties of a substance often changes during this kind reaction.
A chemical change has the following properties:
A new kind of substance forms. It is always accompanied by energy changesInvolves a change in mass of the substanceConsiderable amount of energy is involved in this reaction. The process is irreversibleAnswer:
Both the identity and the properties of a substance change.
Explanation:
In a chemical change, the matter gets transformed or changed into a new substance. In doing this, the identity of the substance, and its properties change as well.
- I got the question right on the quiz and got 100%
Hope this helps!
In the Lewis symbol for a sulfur atom, there are __________ paired and __________ unpaired electrons. A) 2, 2 B) 4, 2 C) 2, 4 D) 0, 6 E) 5, 1 Answer: B
Answer:
C) 2, 4.
Explanation:
Hello!
In this case, since the sulfur atom has six electrons at its outer shell, it suggests it needs to gain two electrons in order to attain a complete octet, that is why it has 2 paired electrons.
Moreover, since two electrons are paired, then 4 electrons will remain unpaired; therefore the answer would be C) 2, 4.
Best regards!
What is the percent composition of silicon dioxide, SiO2 ? (Atomic masses : O = 16 . 0 Si =28 .1
Answer:
60.1 i think
Explanation:
Calculate the number of grams of solid aluminium chloride that will form when a mixture containing 0.150 g of aluminum powder and 1.00 g of chlorine gas is allowed to react.
2Al (s) + 3Cl2 (g) ---> 2AlCl3 (s)
a. 741 g AlCl3
b. 471 g AlCl3
c. 0.741 g AlCl3
d. 246 g AlCl3
Answer:
the answer is B:) have a good day
A compound has a molar mass of 123.22 g/mol. what is the molecular formula of a substance that has this molar mass?
A. CoH4
B. PSF3
C. SrS
D. ZrO2
The answer is (3). The number of Sr is the same so if the compound has the smallest gram formula mass, it has the highest percent composition by mass of strontium. So the answer is (3).
The study of chemical is called chemistry.
The correct answer to the question is option C that is C SrS.
What is molecular mass?The molecular mass is the mass of a given molecule: it is measured in daltons. Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element.The molecular mass of Sr is 87.62 and sulfur is 32 after joining these we will get 123.22.
Hence, the correct answer is option C.
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Help me pls I’m so lost pls ASAP thank you
Answer:
The 2nd answer.
Explanation:
DNA makes people who are related look similar to eachother.
A certain electromagnetic wave has a wavelength of 6.25 x 10-7m. What is the
frequency of the wave?
Answer: 4.80 * 10¹⁴s⁻¹
Explanation:
Speed = Frequency * Wavelength
So:
Frequency = Speed/ Wavelength
Speed of light = 3 * 10⁸ m/s
Frequency = (3 * 10⁸ m/s) / (6.25 x 10⁻⁷m)
= 4.80* 10¹⁴hz
= 4.80 * 10¹⁴s⁻¹
The frequency of the electromagnetic wave is 4.8 x 10¹⁴s⁻¹
In an Electromagnetic wave, The frequency , speed and wavelength of an are related by the formula
λ= c/f
where
λ = wavelength in metres, m.
c= speed of light in metres per sec, m/s
f= frequency in per seconds or hertz,( s⁻¹ , Hz)
Given that Wavelength of the electromagnetic wave is 6.25 x 10-7m.
We know that speed of light is 3 x 10⁸ m/s
Substituting the values into the equation becomes
f = c/ λ
f= 3 x 10 ⁸m /s / 6.25 x 10⁻⁷ m = 4.8 x 10¹⁴s⁻¹
Hence, The frequency of the electromagnetic wave is 4.8 x 10¹⁴s⁻¹
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What volume, IN MILLILITERS, of 5.0M HCl solution is required to react with 3.00 g or magnesium metal?
The volume of HCl = 2.10⁴ mL
Further explanationGiven
5.0 M(mol/L) HCl solution
3 g of Mg
Required
Volume of HCl
Solution
Reaction
Mg + 2HCl ⇒ MgCl₂ + H₂
mol of Mg (Ar=24 g/mol) :
mol = mass : Ar
mol = 3 : 24
mol = 0.125
From the equation, mol ratio of Mg : HCl = 1 : 2, so mol HCl :
= 2/1 x mol Mg
= 2 x 0.125
= 0.25
Molarity : mol solute per liters solution
M = m x V
V = M : m
V = 5 mol/L : 0.25
V = 20 L = 2.10⁴ mL
Answer quick please
Answer:
In my perspective I think its D because Electrical energy is converted to light and heat
