Answer: Inversely , Directly
Explanation:
The energy of a photon is inversely proportional to its wavelength and directly proportional to its frequency.
As can be seen from this equation;
E = hv = h c / ∧
Where E = Energy of a photon
v = Frequency
h = Planck Constant
c = speed of light
∧ = Wave length
150.0 grams of an isotope with a half-life of 36.0 hours is present at time zero. How long will it take
to decay to 18.75g?
Given :
Initial mass , a = 150 gm .
Half time ,
[tex]t_{\dfrac{1}{2}}=36 \ hours[/tex].
Final mass , x = 18.75 gm .
To Find :
The time taken to decay 18.75 gm .
Solution :
We know , time taken is given by :
[tex]t=\dfrac{1}{k}\times ln(\dfrac{a}{a-x})[/tex]
Here , k is a constant given by :
[tex]k=\dfrac{0.693}{t_{\dfrac{1}{2}}}\\\\\\k=\dfrac{0.693}{36}[/tex]
Putting all given value in above equation :
We get :
[tex]t=\dfrac{36}{0.693}\times ln(\dfrac{150}{150-18.75})\\\\t=6.94\ hours[/tex]
Therefore , time taken is 6.94 hours .
Hence , this is the required solution .
ri
1. Among these which is the example of compound?
a) sulphur
b) iron
c) ammonia
der
Answer:
Ammonia is a compound.
Explanation:
A compound is composed of two or more separate elements. Ammonia is NH3, which happens to be two different elements.
What must you know to solve Keller’s third law the law of periods
if i weigh 180 pounds on earth, what will i weigh on the moon?
Answer:
about 30 pounds
Explanation:
The mass of someone on the Moon would be 1/6 of the weight of Earth.
So, 180 ÷ 1/6 = 30.
Hope this helps you!
The answer is 30 pounds because if you weigh an amount of mass on the etah you will weigh 1/6 of it on the moon.
The sum of gravitational potential energy and kinetic
energy is called mechanical energy. Use Figure 2 to find the mechanical energy
of an idealized pendulum at a variety of times in its cycle. Identify any pattern you
notice in the values of mechanical energy.
Answer:
Explanation:
Mechanical energy = Gravitational potential energy + kinetic energy
Time Gravitational potential energy kinetic energy Total ME
0 4 0 4
2 2 2 4
4 0 4 4
6 2 2 4
8 4 0 4
and so on .....
We see that total mechanical energy is always 4 which is constant .
So gravitational and kinetic energy changes cyclically but total mechanical energy is constant .
Which question can be answered by science A:which type of candy taste best B:which kind of backpack do students purchase most often C:why are children happy when they get home D:why should we help those less fortunate than us
Answer:B: Which type of backpack do students purchase most often
Explanation: The right answer is B. because its a question you can graph informational data about, unlike any other answer. Hope this helped!
~Emilie Greene
What is the number at the end of an isotope's name?
O atomic number
O neutron number
O mass number
O electron number
Answer:
c. mass number
Explanation:
Answer:
c mass number tell me if its right
Explanation:
The element rubidium forms a _______ with the charge . The symbol for this ion is , and the name is . The number of electrons in this ion is .
Answer:
The element rubidium forms a cation with a charge of +1. The symbol of this ion is Rb+, and the name is rubidium ion. The number of electrons in this ion is 36 electrons
Explanation:
Rubidium belongs to the group 1A of the periodic table of elements. It is an alkali metal. The rubidium atom has an atomic number of 37. The neutral atom also has 37 electrons.
Being a metal, it forms ions by the loss of electrons. Since it is an alkali metal, it has one valence shell electron. It loses this one electron to form the rubidium ion, Rb+ which then has 36 electrons.
When the equation Sn + HNO₃ → SnO₂ + NO₂ + H₂O is balanced in acidic solution, what is the smallest whole-number coefficient for Sn?
Answer:
1.
Explanation:
Hello,
In this case, for the given reaction we first assign the oxidation state for each species:
[tex]Sn^0 + H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 + N^{4+}O^{2-}_2 + H^+_2O^-[/tex]
Whereas the half reactions are:
[tex]Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow N^{4+}O^{2-}_2+H_2O[/tex]
Next, we exchange the transferred electrons:
[tex]1\times(Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-)\\\\4\times (H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow N^{4+}O^{2-}_2+H_2O)\\\\\\Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\4H^++4H^+N^{5+}O^{-2}_3 +4e^-\rightarrow 4N^{4+}O^{2-}_2+4H_2O[/tex]
Afterwards, we add them to obtain:
[tex]Sn^0+2H_2O+4H^++4H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 +4H^++4N^{4+}O^{2-}_2+4H_2O[/tex]
By adding and subtracting common terms we obtain:
[tex]Sn^0+4H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 +4N^{4+}O^{2-}_2+2H_2O[/tex]
Finally, by removing the oxidation states we have:
[tex]Sn + 4HNO_3 \rightarrow SnO_2 + 4NO_2 + 2H_2O[/tex]
Therefore, the smallest whole-number coefficient for Sn is 1.
Regards.
Which question is most important to developmental psychology?
A. How much do parents influence who a child becomes?
B. How can violent conflicts be prevented?
C. How does brain chemistry affect how we feel and act?
D. How can people change their thinking and behavior?
Answer:
For much of the past century, scientists studying drugs and drug use labored in the shadows of powerful myths and misconceptions about the nature of addiction. When scientists began to study addictive behavior in the 1930s, people with an addiction were thought to be morally flawed and lacking in willpower. Those views shaped society’s responses to drug use, treating it as a moral failing rather than a health problem, which led to an emphasis on punishment rather than prevention and treatment.
Today, thanks to science, our views and our responses to addiction and the broader spectrum of substance use disorders have changed dramatically. Groundbreaking discoveries about the brain have revolutionized our understanding of compulsive drug use, enabling us to respond effectively to the problem.
As a result of scientific research, we know that addiction is a medical disorder that affects the brain and changes behavior. We have identified many of the biological and environmental risk factors and are beginning to search for the genetic variations that contribute to the development and progression of the disorder. Scientists use this knowledge to develop effective prevention and treatment approaches that reduce the toll drug use takes on individuals, families, and communities.
Despite these advances, we still do not fully understand why some people develop an addiction to drugs or how drugs change the brain to foster compulsive drug use. This booklet aims to fill that knowledge gap by providing scientific information about the disorder of drug addiction, including the many harmful consequences of drug use and the basic approaches that have been developed to prevent and treat substance use disorders.
At the National Institute on Drug Abuse (NIDA), we believe that increased understanding of the basics of addiction will empower people to make informed choices in their own lives, adopt science-based policies and programs that reduce drug use and addiction in their communities, and support scientific research that improves the Nation’s well-being.
Answer:
D
Explanation:
f the toxic quantity is 1.5 g of ethylene glycol per 1000 g of body mass, what percentage of ethylene glycol is fatal
Answer:
0.15%
Explanation:
mass of ethylene glycol per 1000 g = 1.5 g
percentage of ethylene glycerol that is fatal = gram of ethylene/gram of the body
==> 1.5/1000 x 100% = 0.15%
1) What mass of Na2CO3 is required to make 50cc of its seminormal solution?
Answer:
[tex]m=1.325gNa_2CO_3[/tex]
Explanation:
Hello,
In this case, by considering the given seminormal solution, we infer it is a 0.5-N solution which means that we can obtain the equivalent grams as shown below for the 55 cc (0.055 L) volume:
[tex]eq-g=0.5eq-g/L*0.050L=0.025eq-g[/tex]
Next, since sodium carbonate has two sodium ions with a +1 oxidation state each, we can obtain the moles:
[tex]mol=0.025eq-gNa_2CO_3*\frac{1molNa_2CO_3}{2eq-gNa_2CO_3}\\ \\mol=0.0125molNa_2CO_3[/tex]
Finally, the mass is computed by using its molar mass (106 g/mol)
[tex]m=0.0125molNa_2CO_3*\frac{106gNa_2CO_3}{1molNa_2CO_3} \\\\m=1.325gNa_2CO_3[/tex]
Regards.
What is all matter I’m the universe made of?
Answer:
The building block that makes up all matter in the universe is atoms.
Help! It’s for chemistry I attached a picture thank you!
Answer:
0.15 L
Explanation:
You need to first find the volume of the container. You can do this by dividing the mass by the density. This will give you the mass in mL.
5.00 kg = 5,000 g
(5,000 g)/(1.00 g/mL) = 5,000 mL
5,000 mL = 5 L
Now, find the volume the seawater will take up.
(5,000 g)(1.03 g/mL) = 4854.4 mL
4854.4 mL = 4.85 L
Subtract the two volumes to find the volume that left unfilled.
5 L - 4.85 L = 0.15 L
Two cars of mass 3000 kg are 2 m apart. What is the force of gravity between the two?
If 12.3 grams of a substance burns in air to produce 15.9 grams of a compound, what mass of the air reacted?
Answer:
[tex]m_{air}=3.6g[/tex]
Explanation:
Hello,
In this case, given the law of conservation of mass which states that mass cannot be created nor destroyed, since the produced mass of the compound is 15.9 g and the mass of the initial substance is 12.3 g we obtain the mass of air by applying the following equation:
[tex]m_{reactants}=m_{products}\\\\m_{substance}+m_{air}=m_{product}[/tex]
Thus, solving for the mass of air we obtain:
[tex]m_{air}=m_{product}-m_{substance}\\\\m_{air}=15.9g-12.3g\\\\m_{air}=3.6g[/tex]
Regards.
In which of the following sets do all species have the same number of electrons?
A) F-,Ne, Mg2+
B) Ge, Se2-, Br-
C) K+,Rb+, Cs+
D) Br, Br-, Br+
What does science mean to you
Answer:
Sample Essay On What Science Means to You. ... Entire knowledge acquired through science is about discovering truths, finding facts, uncovering phenomenon hidden by the nature. Observations and experimentation, in science, support in describing truth and realities through systematic processes and procedures.
Explanation:
Science is the pursuit and application of knowledge and understanding of the natural and social worlds according to systematic and evidence-based methodologies. Scientific methodologies include: Objective Observations: Measurements and Data (Math may be used as a tool, but not always)
What is the importance of science in our lives?Science plays an important role in our daily lives. It made our lives easier and more convenient. Science is just a systematic way of knowledge and life. The exploratory, careful and careful observation of changes in natural events by humans has produced science and scientific research.
Science plays an important role in our daily lives. It made our lives easier and more convenient. Science is nothing but a systematic way of knowledge and life. The exploratory, careful and careful observation of changes in natural events by humans has produced science and scientific research.
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4.80 qt is the same as how many mL?
Answer:
1qt is the same as 946.35mL
Explanation:
4.80 US liquid quart is equal to 4542. 49 mL.
What is a US liquid quart?A quart is a unit for capacity used in the Imperial British and the U.S. Customary systems of measurement. It is used for both liquid and dry measurements, one standard quart is used in the British system. This is equal to two imperial pints, or one-fourth of the imperial gallon.
This is 69.36 cubic inches or 1,136.52 cubic cm. The U.S. system of measurements has two units for a quart. One is used for the liquid measurements and a slightly larger unit is used for the dry measurements.
The U.S. liquid quart unit is equal to two liquid pints, or one-fourth U.S. gallon. This is 57.75 cubic inches or 946.35 cubic cm. The dry quart is equal to two dry pints, or 1/32 bushel. This is 67.2 cubic inches or 1,101.22 cubic cm.
In this case, 1 US quart = 946.353 ml
So, 4.80 liquid quart = 4542.49 ml.
Therefore, 4.80 US liquid quart is equal to 4542. 49 mL.
Read more about US quart, here
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Classify each as a physical or chemical change.
Explain each answer.
a) When limestone is heated carbon dioxide and
calcium oxide result.
b) Digesting a candy bar.
c) Copper can be drawn into thin wires.
d) Ripening of fruits.
e) Ice floats on water
Answer:
a) When limestone is heated in a kiln, the calcium carbonate breaks down into calcium oxide and carbon dioxide. This type of reaction is called thermal decomposition. The process is called calcining. ... Slaked lime is used to reduce the acidity of the soil, which helps increase its fertility.
b) Mechanical digestion occurs in the mouth, stomach, and small intestine. Food is chemically changed indigestion when new, smaller substances are formed. These chemical changes are examples of chemical digestion. Chemical digestion begins in the mouth when enzymes in saliva begin to break down carbohydrates.
c) Copper is a ductile metal. This means that it can easily be shaped into pipes and drawn into wires. Copper pipes are lightweight because they can have thin walls. They don't corrode and they can be bent to fit around corners.
d) Ripening of fruits is a chemical change. During ripening the pigment present in the skin of the fruit changes and this can not be reversed back. it is a chemical change as once a fruit ripens it cannot turn raw again.
e) Ice is a unique substance because it is solid-state — ice — is less dense than its liquid state. Because of this property, ice floats in water. Physical properties are characteristics of a substance. They do not change. Physical properties include colour, smell, freezing/melting point, and density.
Considering the redox reaction Cr + Ni²⁺ → Cr³⁺ + Ni, how many electrons are transferred in the balanced reaction?
Answer:
The correct answer is : 6 electrons
Explanation:
From the reduction-oxidation reaction, we identify the half-reactions:
Oxidation reaction: Cr (oxidation number= 0) loses 3 electrons and forms the cation Cr³⁺.
Cr → Cr³⁺ + 3 e-
Reduction reaction: the cation Ni²⁺ gains 2 electrons to form Ni (oxidation number= 0).
Ni²⁺ + 2 e- → Ni
We write the two half-reactions together and we multiply the reduction reaction by 3 and the oxidation reaction by 2 to obtain the same quantity of electrons in each half-reaction: 6.
(Ni²⁺ + 2 e- → Ni) x 3
(Cr → Cr³⁺ + 3 e-) x 2
-------------------------------
3 Ni²⁺ + 2 Cr → 3 Ni + 2 Cr³⁺ (balanced reaction)
Therefore, in the balanced reaction a total of 6 electrons are transferred.
if an atom has 17 protons and 18 neutrons, what is the charge of the atom's nucleus?
dont need time cause time waiting on nobody
For the experiments from 1-3 with the same temperature change, what other parameters are the same at the initial reaction conditions?
a. mmol HCl total mL solution
b. mmol NaOH Initial concentration of NaOH
c. mL H2O Initial concentration of HCl
Answer:
The following parameters:
total mL solution mmol NaOH initial concentration of NaOHExplanation:
The options have been incorrectly arranged in the question statement given here. The three conditions mentioned above are what would be observed to remain the same when this experiment is carried out.
g A sample of unknown gas has a mass of 1.95 g and occupies 3.00 L at 1.25 atm and 20 C. What is the molar mass of the unknown gas
Answer:
Molar mass = 12.51 g/mol
Explanation:
V = 3L
P = 1.25 atm
T = 20 C = 20 + 273 = 293 K (Upon conversion to kelvin temperature)
n =?
m = 1.95g
Molar mass = ?
The variables are related by the follwing equation;
pV = nRT
where r = gas constant = 0.0821 L atm K−1
Solving for n, we have;
n = pV / RT
n = (1.25 * 3 ) / (0.0821 * 293)
n = 3.75 / 24.0553 = 0.1559 mol
The relationship between number of moles, n and molar mass is given as;
n = mass / molar mass
Molar mass = Mass / n = 1.95 / 0.1559
Molar mass = 12.51 g/mol
Volume pressure= .785 liters
Unknown 1 = 1884 torr
Unknown 2 = 847 torr
Now that the volume of the pressure vessel is known, the number of moles H2 gas formed can be determined for the unknown samples. Enter the corrected gas pressure after subtracting the water vapor pressure for unknowns 1 and 2
Unknown 1 corrected pressure?
Unknown 2 corrected pressure?
Use the ideal gas equation and the volume obtained above to calculate the number of moles H2 gas produced during each unknown run. Assume again that the gas temperature at the end of each run is 22 degrees C
Unknown 1?
Unknown 2?
Divide the sample mass by the number of moles of H2, calculated above to determine the ratio of sample mass to number of moles of H2, produced.
Answer:
corrected pressure : unknown 1 = 2.452 Atm, unknown 2 = 1.088 atm
number of moles : unknown 1 = 0.079 moles unknown 2 = 0.035263 moles
Explanation:
Given data:
volume pressure = 0.785 liters
Unknown 1 = 1884 torr (1884 mmhg )
Unknown 2 = 847 torr ( 847 mmhg )
vapor pressure at 22⁰c = 19.8 mmhg
Determine the number of moles of H2 gas for the unknowns
unknown corrected pressure for unknown 1 = total pressure - vapor pressure = 1884 - 19.8 = 1864.2 mmhg / 760 = 2.452 Atm
no of moles = PV / RT
T = 22 + 273.15 = 295.15 k
P = 2.452 atm
R = 0.08206L.atm/mole.K
v = 0.785
number of moles = (2.452 * 0.785 ) / (0.08206 * 295.15 ) = 0.079 moles of
Unknown corrected pressure for unknown 2 = total pressure - vapor pressure = (847 - 19.8 ) / 760 = 1.088 atm
number of moles = PV / RT
T = 22 + 273.15 = 295.15 k
R = 0.08206L.atm/mole.K
v = 0.785
P = 1.088 atm
number of moles = (1.088 * 0.785 ) / (0.08206 * 295.15 ) = 0.035263 moles
B ) determine the ratio of sample mass to number of moles
molar mass of H2 = 2.01588 g/mole
for unknown 1 = 2.01588 / 0.079 = 25.51
for unknown 2 = 2.01588 / 0.035263 = 57.167
What is the density of an object with a volume of 30ml and a mass of 90 grams
Answer:
Density = 3 g/mLExplanation:
Density of a substance can be found by using the formula
[tex]Density = \frac{mass}{volume} [/tex]From the question
mass = 90 g
volume = 30 mL
Substitute the values into the above formula and solve for the Density
That's
[tex]Density = \frac{90}{30} \\ = \frac{9}{3} [/tex]We have the final answer as
Density = 3 g/mLHope this helps you
A chemistry teacher spends 35 minutes grading 1 students lab. They have 153 students who turn in lab papers for each lab. If the class completed 25 labs, how many minutes will the teacher spend grading lab papers? I just need to know how to set up the problem and the answer, thank you!!
Answer:
13,3875 minutes or 2,231.25 hours
Explanation:
153 x 25 = 3,825
person x lab paper = all the lab papers turned in.
35 x 3,825 = 13,3875
minutes x all the lab papers turned in = amount of minutes spent on grading
Which acid-base pairs would be best for preparing a buffer solution with a PH of 8.15?
Answer:
HCN - CN⁻ (pair #4)
Explanation:
Hello,
In this case, for the selection of best pair for the preparation of the buffer solution with a pH of 8.15 we need to look for the one having the pKa closest to the required pH, considering the Henderson-Hasselbach equation:
[tex]pH=pKa+log(\frac{[base]}{[acid]} )[/tex]
In such a way, among the options, the pair HCN - CN⁻ (#4) has a pKa of 9.39 which is the closest in comparison to the others, taking into account the we will look for a [base]/[acid] ratio approaching 1.
Best regards.
Water flows over Niagara Falss at the average rate of 2,400,000 kg/s, and the average height of the falls is about 50 m. Knowing that the graviatational potential energy of falling water per second = mass (kg) x height (m) x gravity (9.8 m/s2), what is the power of Niagara Falls? How many 15 W LED light bulbs could it power?
Answer:
1. 176 × 10^12 W ; 78400000000
Explanation:
Given the following :
Fall rate = 2,400,000kg/s
Average height of fall = 50m
Gravitational Potential of falling water = mgh = mass × acceleration due to gravity × height =
How many 15 W LED light bulbs could it power?
Recall : power = workdone / time
Workdone = gravitational potential energy
Mass of water = density * volume
Density of water = 1 * 10^3kg/m^3
Rate of fow = volume / time = 2400000
Hence,
Power = 1000 * 2,400,000 * 9.8 * 50
Power = 1176000000000
Power = 1. 176 × 10^12 W
How many 15 W LED light bulbs could it power?
1176000000000 / 15 = 78400000000
= 78400000000 15 W bulbs
which variable is directly proportional to frequency?
velocity
wavelength
position
energy
Answer:
its letter D Energy I think