A scientist wants to test the effectiveness of a medicine in treating
headaches. He puts the medicine into cookies and then tells his subjects to
lie down and have a cookie when they have a headache. He asks them to give
him feedback about how well these relaxation techniques work to cure their
headaches. What rule of ethics does this experiment break?
O A. The subjects are not informed that they are taking a medicine.
B. It is likely to harm his subjects.
C. The scientist is taking the work of others by reviewing the
subjects' feedback.
D. It is testing more than one variable at the same time.
1. How much heat is required to raise the temperature of 4.64kg of lead from 150°C to 219°C?
Answer: An amount of [tex]40980.48 J/g^{o}C[/tex] heat is required to raise the temperature of 4.64kg of lead from 150°C to 219°C.
Explanation:
Given: mass of lead = 4.64 kg
Convert kg into grams as follows.
[tex]1 kg = 1000 g\\4.64 kg = 4.64 kg \times \frac{1000 g}{1 kg}\\= 4640 g[/tex]
[tex]T_{1} = 150^{o}C[/tex]
[tex]T_{2} = 219^{o}C[/tex]
The standard value of specific heat of lead is [tex]0.128 J/g^{o}C[/tex].
Formula used to calculate heat is as follows.
[tex]q = m \times C \times \Delta T[/tex]
where,
q = heat energy
m = mass of substance
C = specific heat of substance
[tex]\Delta T[/tex] = change in temperature
Substitute the value into above formula as follows.
[tex]q = m \times C \times \Delta T\\= 4640 g \times 0.128 J/g^{o}C \times (219 - 150)^{o}C\\= 40980.48 J/g^{o}C[/tex]
Thus, we can conclude that [tex]40980.48 J/g^{o}C[/tex] heat is required to raise the temperature of 4.64kg of lead from 150°C to 219°C.
what is the equation for the reaction between excess dry oxygen and iron fillings
Answer:
Fe2 + O2 > FeO
Explanation:
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Which of the following is true of squalene, a hexa-unsaturated hydrocarbon
with a formula of C₃₀H₅₀, which melts at – 5°C and boils at 285 °C?
Answer: The alkyne
Explanation:
Answer:
the alkyne
Explanation:
Hope it helps u
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An _______________________ (device that converts electrical energy into kinetic energy) runs by using the magnetic field formed by a ______________________________ formed into a loop.
Answer:
A motor (device that converts electrical energy into kinetic energy) runs by using the magnetic field formed by a flowing current formed into a loop.
plzz help 20 points plzzzz
The answer is: Element B
how much more acidic is a solution with a pH of 1 than a solution with a pH of 3
Answer:
A solution whose pH=1 is ten times more acidic than the solution whose pH=2.
Explanation:
17. If the pOH of a solution is 4.5, What is the pH ?
A) 8.5
B) 7.5
C) 9.5
D) 7.0
Answer:
C)9.5
Explanation:
Given poH=4.5
find ph
from 14=ph+poh
14=ph+4.5
ph=9.5
How many kilojoules of heat must be transferred to a 480-g aluminum pizza pan to raise its temperature from 22°C to 234°C? The specific heat of aluminum in this temperature range is 0.96 J/g.°С. Show your work.
Answer:
97.7 kJ
Explanation:
We'll use the formula for specifc heat: Q=mcΔT
Q= heat/energy (Joules), m= mass (grams), c= specific heat (different for each substance and is usually given)
ΔT= final temperature - initial temperature
Let's check our given units and see if they're the correct, here they all are. Let's plug in what we know.
Q=mcΔT
Q=(480)(0.96)(234 - 22)
Q=(480)(0.96)(212)
Q= 97,690 J
Before we submit an answer, let's check out units. We have our answer in Joules, but we want it it kilojoules, so we'll convert it knowing that:
1000 Joules = 1 kilojoule
97,690J x [tex]\frac{1 kJ}{1000J}[/tex] = 97.7kJ
Explanation:
the answer and the working out is shown above.
What is the pH of a solution with a 3.2 x 10−6 M hydronium ion concentration?
Answer:
5.49Explanation:
The pH of a solution can be found by using the formula
[tex]pH = - log ([ { H_3O}^{+}])[/tex]
H3O+ is the hydronium ion
From the question we have
[tex]pH = - log(3.2 \times {10}^{ - 6} ) \\ = 5.49485..[/tex]
We have the final answer as
5.49Hope this helps you
which of the following elements has the highest electronegativity?
A) oxygen
B) nitrogen
C) carbon
D) boron
Answer:
option d) is the correct answer
UNA ONDA SE MUEVE CON UNA FRECUENCIA DE 2 (HZ), Y SU RAPIDEZ DE PROPAGACIÓN ES DE 20 (m/s). ¿Cuál ES LA LONGITUD DE ONDA.
A student dissolves 0.112 mol sucrose in enough water to make 4.0 L of solution. What is the molarity of the solution
Answer: Molarity of the solution is 0.028 M.
Explanation:
Given : Moles of sucrose (solute) = 0.112 mol
Volume of solution = 4.0 L
Molarity is the number of moles of solute dissolved in a liter of solvent.
[tex]Molarity = \frac{no. of moles}{Volume (in L)}\\= \frac{0.112 mol}{4.0 L}\\= 0.028 M[/tex]
Thus, we can conclude that molarity of the solution is 0.028 M.
A gas occupies 12.3 L at a temperature of 40.0 K. What is the volume when the temperature is increased to 60.0 K?
Answer:
the volume is 18.45 L
Explanation:
The computation of the volume when the temperature is increased to 60.0 K is shown below:
Since the gas occupied 12.3 L at a temperature of 40.0 k
And, the volume when the new temperature is 60.0 k
So, the volume is
= 60.0 k × 12.3 L ÷ 40.0 k
= 18.45 L
hence, the volume is 18.45 L
Which lunar phase is 21 days after the first quarter?
Answer: waning gibbous
Explanation:
How many moles of calcium oxide are formed when 3 moles of calcium react with oxygen?
Answer:
3 moles of Calcium Oxide are formed
Explanation:
Based on the reaction of Calcium Ca, with oxygen, O₂, to produce calcium oxide, CaO is:
2Ca + O₂ → 2CaO
where 2 moles of calcium produce 2 moles of Calcium oxide.
That means, if 3 moles of Ca react in presence of oxygen:
3 moles of calcium oxide are formed
Identify the gas law that applies to the following scenario: A 36.5 liter balloon holding 2.9 moles of carbon dioxide leaks. If we are able to determine that 1.2
moles of carbon dioxide escaped before the container could be sealed, what is the new volume of the container?
O Boyle's Law
Charles Law
Gay-Lussac's Law
Avogadro's Law
Answer:
Avogadro's Law
Explanation:
The amount of moles is directly proportional to the volume of the gas under constant temperature and pressure. That is the statement of Avogadro's law. The equation is:
V1n2 = V2n1
Where V is volume and n are moles of 1, initial state and 2, final state of the gas
That means, right option is:
Avogadro's LawQuestion 25 of 33
Which statement describes a periodie trend of brstionization energy?
A It tends to increase from top to bottom of a group
B. It remains the same within a period
c. It tends to decrease from top to bottom of a group
D. It tends to decrease from left to right across a period
Answer:
A) It tends to increase from top to bottom of a group
Complete and balance the following neutralization reaction, and estimate the
likely pH of the neutralization point. (3 pts)
Ca(OH)2 + HNO3 →
Answer:
we have a base-Ca(OH)2 and an acid - HNO3
→Their chemical reaction gives us water and salt Ca(NO3)+ H20 (neutralisation reaction)
the pH is expected to be acidic ... since nitric acid is a strong acid and calcium hydroxide is a weak base .
Explanation:
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An ambulance took 2 hours to cover a distance of 10 kilometers. Find its speed.
Answer:
5km/hour
Explanation:
2hours = 10km
/2 /2
1 hour = 5km
An ambulance took 2 hours to cover a distance of 10 kilometers. Find its speed.
Answer:-Given:-Distance = 10 kilometers.
Time = 2 hours.
To Find:-Its speed.
Solution:-We know,
[tex] { \boxed{\bf{\rm \red {Speed \: = \: Distance \: × \: Time}}}} [/tex]
Speed = 10 kilometers × 2 hours
Speed = 20 km/hr
Its speed is 20 km/hr. [Answer]justin noticed several cracks in the sidewalk. Weeds are growing through them, cause the crack to expand. What process is this?
Answer:
Explanation:
Weeds and Small Plant Roots Exploit Existing Concrete Cracks
Instead, the plant's roots take advantage of existing microscopic cracks. New cell growth takes place at the tips of plant roots. ... Eventually, molecule by molecule, the plant's growth can force its way into the slab and create a surface crack.
What causes the pressure inside oxygen tanks to change as they are filled?
A. The temperature of the gas changes.
B. The volume of the container changes.
C. The pressure outside the tanks changes.
D. The number of gas molecules changes.
Answer:
The answer would be D.
: )
Explanation:
The number of gas molecules changes as the pressure inside oxygen tanks changes as they are filled. option D is correct.
What are oxygen tanks?Oxygen tanks are those in which the oxygen is filled in the liquid form by giving pressure to it with the help of a piston due to more pressure the molecules of oxygen become close.
As the molecule of the oxygen gas is closed to each other they are condensed and changes their state from a gaseous state to a liquid state.
By providing more pressure to the oxygen tank the gas molecules increases due to the decrease in the surface of the tank and molecules condense to liquid form.
Therefore, The number of gas molecules changes as the pressure inside oxygen tanks changes as they are filled. option D is correct.
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For the simple reaction of A + B ---> C, if A is the limiting reactant for a certain set of conditions, then B is an excess reactant. True or False
Answer: True
Explanation:
What of the following is NOT a common property of metals?
Answer:
the last one
Explanation:
liquid at room temp
Which fraction contains the largest molecules?
A) diesel
B)gasoline
C)kerosene?
Answer:
Hydrocarbons
Hydrocarbons are chemical compounds that contain the elements carbon and hydrogen only. They are compounds that are obtained from the fossil fuel crude oil by a process called fractional distillation.
Fractional distillation
Fractional distillation separates the crude oil mixture into a number of smaller, different parts called fractions. The fractionating column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with lower boiling points condense on the way to the top.
The crude oil is evaporated and its vapours condense at different temperatures in the fractionating column. Each fraction contains hydrocarbon molecules with a similar number of carbon atoms, smaller molecules nearer the top and longer molecules nearer the base of the column.
Oil fractions
The diagram below summarises the main fractions from crude oil and their uses and the trends in properties. Note that the gases leave at the top of the column, the liquids condense in the middle and the solids stay at the bottom.
Explanation:
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The substances which are generally used to generate heat and light energy on burning are called fuels. The diesel fuel contains the largest molecules. Thus option A is correct.
What is Diesel?The diesel fuel which is also called the diesel oil is found to be a combustible liquid and it is produced from the fractions of crude oil. The diesel fuel is found to be less volatile than the gasoline.
The chemical composition of a diesel fuel is usually denoted as C₁₂H₂₄. Apart from the carbon and hydrogen atoms small amounts of 'S', 'N' and 'O' are also present in the diesel.
Here gasoline is a derivative product obtained by the fractional distillation of crude oil and it is generally used in passenger vehicles whereas kerosene is a highly flammable liquid obtained from the distillation of petrol and is less volatile than gasoline.
The gasoline contains only 4 to 12 'C' atoms per molecule and it is a lightweight hydrocarbon mixture. The number of 'C' atoms in kerosene ranges from 10 to 16 per molecule and the diesel fuel is known as the heavyweight hydrocarbon mixture with 8 to 21 'C' atoms per molecule.
Thus diesel fuel consists of larger hydrocarbon molecules than gasoline and kerosene.
Thus the correct option is A - Diesel.
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Which family on the periodic table is least likely to enter into chemical reactions?
1
2
17
18
Answer:
the answer is seventeen
DOS MOVILES PARTEN A LAS 12:00 AL MISMO TIEMPO HACIA EL NORTE DEL PAIS .¿ QUE DISTANCIA LOS SEPARA A LAS 13 HORAS SUPONIENDO QUE SUS VELOCIDADES SON 20 M/S Y 50 K/H ?
Answer:
22km
Explanation:
Las velocidades de los móviles nos van a definir cuánta distancia recorren por unidad de tiempo. Para resolver este problema debemos hallar la distancia recorrida en una hora por cada vehículo (Porque de las 12 horas a las 13 solo hay una hora)
Un móvil está recorriendo 50km/h. En una hora recorrerá: 50km
El otro móvil recorre 20m/s. En km/h:
20m/s * (3600s / h) = 72000m/h * (1km / 1000m) = 72km/h. El móvil recorrerá, en una hora, 72km
1h = 3600s; 1km = 1000m
La distancia que los separa es de:
72km - 50km =
22km
Under similar conditions, which gas diffuses most rapidly through a small
opening?
a. Methane, CH4
b. Carbon dioxide
C. Sulfur dioxide
d. Oxygen
e. Chlorine
Answer:
e
Explanation:
a
Conclusion:
sports
Si la masa de una muestra de un compuesto Y es de 196 gramos y contiene 2 mol, la masa molar de Y es
Answer:
98 g/mol
Explanation:
La masa molar de un compuesto es la cantidad de materia (medida como masa) que hay en 1 mol de dicho compuesto. Por lo tanto, puede calcularse como sigue:
masa molar = masa/número moles
Tenemos los siguientes datos del compuesto Y:
masa Y = 196 g
número de moles de Y = 2 mol
Entonces, podemos calcular la masa molar de Y de la siguiente manera:
masa molar Y = (masa Y)/(número de moles de Y) = 196 g/2 mol = 98 g/mol
Which model could represent a neutral atom of nitrogen
Answer:
The answer is c.1. The atomic number of nitrogen is 7.
The electron arrangement of nitrogen is 2.5. With that said, atom 1 resembles the neutral atom of nitrogen because the innermost shell of the atom contains 2 electrons while the outermost shell of the atom contains 5 electrons.
The model that could represent a neutral atom of nitrogen is the first one. Thus, the correct option is C.
What is a Nitrogen atom?A nitrogen atom may be defined as a chemical element with an atomic number of 7 and an atomic mass of 14. It contains seven protons in its nucleus.
Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table. Being neutral, the number of protons that it has in its nucleus must be equal to that of the surrounding electron. Hence, the number of electrons are seven.
These seven electrons are only visible in the first model. Thus, the correct option for this question is C.
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