Answer:
The scientists and all test subjects involved in the investigation work for the company that sells the medication.
Explanation:
The options are as below:
A. The investigation compared a group that took the medication to a control group that did not take the medication.
B. The scientists and all test subjects involved in the investigation work for the company that sells the medication.
C. The weight loss medication worked for 95 out of the 100 test subjects, while only 15 of the 100 control subjects lost weight.
D. The weight loss results were replicated by scientists conducting a study at an independent institution
The correct option would be that the scientists and all test subjects involved in the investigation work for the company that sells the medication.
When selecting the test subjects for research, the selection must be as random as possible so as to ensure an unbiased outcome and increase the reliability of the research.
Limiting the test subjects to those that work in the company that sells the medication will generally reduce the reliability of the outcome because of element of bias that can be introduced either knowingly or unknowingly.
The test subjects must have been selected from the general population of target users for the medication and not limited to just the employees of the manufacturing company.
Correct option: B
Given that the density of air is 14.4, then the vapour of sulphur IV oxide is A. 16 B. 32 C. 64 D. 128
Thank you.
Answer:
32
Explanation:
The vapour density of a gas is the number of times a given volume of gas or vapour is as heavy as the same volume of hydrogen at a particular temperature and pressure.
Vapour density = 2 × relative molecular mass of the gas or vapour
Relative molecular mass of SO2 = 32 + 2(16) = 64
Hence;
Vapour density of SO2 = 64/2
Vapour density of SO2 = 32
how much of the excess reactant remains unchanged?
how much N2 is formed? (in mol)
how much H2O is firmed? (in mol)
Answer:
1. The limiting reactant is H2O2.
2. The amount of excess reactant, N2H4 that remain unchanged is 11.15 moles.
3. 1.65 moles of N2.
4. 6.6 moles of H2O.
Explanation:
We'll begin by writing the balanced equation for the reaction. This is given below:
N2H4 + 2H2O2 —> N2 + 4H2O
From the balanced equation above,
1 mole of N2H4 reacted with 2 moles of H2O2 to produce 1 mole of N2 and 4 moles of H2O.
1. Determination of the limiting reactant.
From the balanced equation above,
1 mole of N2H4 reacted with 2 moles of H2O2.
Therefore, 12.8 moles of N2H4 will react with = 12.8 x 2 = 25.6 moles of H2O2.
From the calculations made above, we can see that it will take a higher amount i.e 25.6 moles than what was given i.e 3.3 moles of H2O2 to react completely with 12.8 moles of N2H4.
Therefore, H2O2 is the limiting reactant and N2H4 is the excess reactant.
2. Determination of the excess reactant that remain unchanged.
The excess reactant is N2H4.
First, we shall determine the amount of the excess reactant that reacted. This is illustrated below:
From the balanced equation above,
1 mole of N2H4 reacted with 2 moles of H2O2.
Therefore, Xmol of N2H4 will react with 3.3 moles of H2O2 i.e
Xmol of N2H4 = (1 x 3.3)/2
Xmol of N2H4 = 1.65 moles
Therefore, 1.65 moles of N2H4 reacted.
Now, we shall determine the excess reactant that remain unchanged. This can be obtained as follow:
Amount of N2H4 given = 12.8 moles
Amount of N2H4 that reacted = 1.65 moles.
Amount of N2H4 that remain unchanged =?
Amount of N2H4 that remain unchanged = (Amount of N2H4 given) – (Amount of N2H4 that reacted = 1.65 moles)
Amount of N2H4 that remain unchanged = 12.8 – 1.65
Amount of N2H4 that remain unchanged = 11.15 moles.
3. Determination of the amount of N2 produced.
In this case, the limiting reactant will be used because it will give the maximum yield of N2 as all of it is used up in the reaction.
The limiting reactant is H2O2 and the amount of N2 produced can be obtained as follow:
From the balanced equation above,
2 moles of H2O2 reacted to produce 1 mole of N2.
Therefore, 3.3 moles of H2O2 will react to produce = (3.3 x 1)/2 = 1.65 moles of N2.
Therefore, 1.65 moles of N2 were obtained from the reaction.
4. Determination of the amount of H2O produced.
In this case, the limiting reactant will be used because it will give the maximum yield of H2O as all of it is used up in the reaction.
The limiting reactant is H2O2 and the amount of H2O produced can be obtained as follow:
From the balanced equation above,
2 moles of H2O2 reacted to produce 4 moles of H2O.
Therefore, 3.3 moles of H2O2 will react to produce = (3.3 x 4)/2 = 6.6 moles of H2O.
Therefore, 6.6 moles of H2O were produced from the reaction.
Iron and aluminum are examples of
Answer:
Iron and aluminum are both examples of metals that are used commonly in everyday life.
100 cm^3 of oxygen diffuses through a Porous in 3second how long will it take 150 cm^3 of sulphur (iv) oxide diffuse through the same pot? ( oxygen= 16 sulphur = 32)
Answer:
3.18 seconds
Explanation:
Given the following :
Volume of oxygen (V1) = 100cm^3
Time taken (t1) = 3 seconds
Volume of Sulphur (iv) oxide (v2) = 150cm^3
From Graham's Law of diffusion:
(r1/r2) = √(m1/m2)
Where r = rate of diffusion
m = molar mass
Note rate (r) = (volume / time)
[(V1/t1) ÷ (v2/t2)] = √(m1/m2)
(v1/t1) * (t2/v2) = √(m1/m2)
m1 = 02 = (16 * 2) = 32
m2 = SO2 = (32 + (16 * 2)) = 64
(100/3) * (t2/150) = √(32/64)
100t2 / 450 = √(32/64)
100t2 / 450 = √32 / 8
100t2 / 450 = √32 / 8
100t2 * 8 = 450 * √32
800t2 = 2545.5844
t2 = 2545.5844 / 800
t2 = 3.1819805
t2 = 3.18 seconds
It will take 3.18s for 150cm^3 of Sulphur (iv) oxide to diffuse through the same pot.
How many moles of potassium in 73.56g of potassium chlorate (V) (KClO 3 )?
Answer:
Approximately [tex]0.6003\; \rm mol[/tex] formula units.
Explanation:
Formula Mass of KClO₃Look up the relative atomic mass data for [tex]\rm K[/tex], [tex]\rm Cl[/tex], and [tex]\rm O[/tex] on a modern periodic table:
[tex]\rm K[/tex]: [tex]39.908[/tex].[tex]\rm Cl[/tex]: [tex]35.45[/tex].[tex]\rm O[/tex]: [tex]15.999[/tex].The relative atomic mass of an element is numerically equal to the mass (in grams) of one mole of its atoms. For example, the relative atomic mass of [tex]\rm K[/tex] is [tex]39.908[/tex]. Therefore, the mass of one mole of [tex]\rm K\![/tex] atoms should be [tex]39.908\; \rm g[/tex].
Each [tex]\rm KClO_3[/tex] "formula" unit includes one [tex]\rm K[/tex] atom, one [tex]\rm Cl[/tex] atom, and three [tex]\rm O[/tex] atoms. Therefore, one mole of [tex]\rm KClO_3\![/tex] formula units would include:
one mole of [tex]\rm K[/tex] atoms, one mole of [tex]\rm Cl[/tex] atoms, and three moles of [tex]\rm O[/tex] atoms.From the relative atomic mass of these three elements:
The mass of one mole of [tex]\rm K[/tex] atoms would be [tex]39.908\; \rm g[/tex].The mass of one mole of [tex]\rm Cl[/tex] atoms would be [tex]35.45\; \rm g[/tex].The mass of three moles of [tex]\rm O[/tex] atoms would be [tex]3 \times 15.999\; \rm g = 47.997\; \rm g[/tex].Combining these three parts should give the mass of one mole of [tex]\rm KClO_3[/tex] formula units:
[tex]\begin{aligned}& M(\mathrm{KClO_3}) \\ &= 39.908 + 35.45 + 3 \times 15.999 \\ &= 122.545\; \rm g \cdot mol^{-1}\end{aligned}[/tex].
Number of moles of KClO₃ formula units in the sampleThe formula mass of [tex]\rm KClO_3[/tex] is [tex]M(\mathrm{KClO_3}) = 122.545\; \rm g \cdot mol^{-1}[/tex], meaning that the mass of one mole of [tex]\rm KClO_3\![/tex] formula units would be [tex]122.545\; \rm g\![/tex].
The mass of this [tex]\rm KClO_3\!\![/tex] sample is [tex]m(\mathrm{KClO_3}) = 73.56\; \rm g[/tex]. The number of moles of formula [tex]\rm KClO_3\![/tex] units in this sample would be:
[tex]\begin{aligned}n(\mathrm{KClO_3}) &= \frac{m(\mathrm{KClO_3})}{M(\mathrm{KClO_3})} \\ &= \frac{73.56\; \rm g}{122.545\; \rm g \cdot mol^{-1}} \approx 0.6003\; \rm mol\end{aligned}[/tex].
To know the exact number of mole of potassium (K) in 73.56 g of potassium chlorate (v), KClO₃ do the following:
Step 1:Determination of the number of mole in 73.56 g of potassium chlorate (v), KClO₃
Mass of KClO₃ = 73.56 g
Molar mass of KClO₃ = 39 + 35.5 + (16×3)
= 39 + 35.5 + 48
= 122.5 g/mol
Mole of KClO₃ =?[tex]Mole =\frac{mass}{molar mass}\\\\Mol KClO_{3} = \frac{73.56}{122.5}[/tex]
Mole of KClO₃ = 0.6 moleStep 2:Determination of the number of mole of potassium, K in 0.6 mole (i.e 73.56 g) of KClO₃
Considering the molecular formula of potassium chlorate (v), KClO₃, we can see that:
1 mole of KClO₃ contains 1 mole of K.
Therefore, 0.6 mole of KClO₃ will also contain 0.6 mole of K.
Therefore, we can conclude that 73.56 g of KClO₃ contains 0.6 mole of potassium, K.
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What three things are required for a fire to start?
Copper turns a green-brown when it is exposed to oxygen in air. What chemical property of oxygen causes this effect? A. its reactivity B. its volume C. its mass D. its flammability
Answer:
A. its reactivity
Explanation:
It's reactivity because copper was exposed to air and if it is reactivity it must be exposed to air
Answer:
A. reactivity
Explanation:
Which of the following is an example of matter? Question 5 options: A) The air around you B) Your thoughts C) Radio waves D) Heat from a fire
Answer:
the air around you
Explanation:matter is physical like the particles in the air or the oxygen in the air. so rocks, earth the sun, anything you can touch is matter. even gasses.
What characteristic best describes the low entropy associated with solids?
O A. The atoms are held together with strong bonds.
O B. The atoms are arranged in a rigid structure.
C. The solid has a high specific heat capacity
D. The atoms in a solid are mostly metals.
Answer:
B. The atoms are arranged in a rigid structure.
Explanation:
Because the entropy of solids depends on the structure of the atoms, a rigid structure has less randomness = less entropy. So, the answer is B.
Answer:
b
Explanation:
a p e x :)
PLEASE HELP WILL GIVE BRAINLIEST!!!!
Which of the following is the best definition of a chemical property?
A. The solubility of salt.
B. The ability of gunpowder to explode.
C. The ability of something to undergo a change or reaction.
D. Something that can be observed or measured without changing the identity of the substance.
Answer:
The B. Is perfect match of a definition of chemical property.
Explanation:
The ability of gunpowder to explode.
The ability of gunpowder to explode is the best definition of a chemical property.
What is chemical property?The change of one type of matter into another type of matter and inability to change into the previous forms is called a chemical property. Examples of chemical properties include reactivity and heat of combustion.
So we can conclude that the ability of gunpowder to explode is the best definition of a chemical property.
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differences between properties of convalent and ionic bond.
Ionic bonds will be a metal + a nonmetal, and electrons
are transferred from the metal to the nonmetal.
A covalent bond will be a nonmetal only. Nonmetals will not give up their electrons so electrons are shared.
I have also written this on the whiteboard in the image provided.
What wavelength measures
A. Depth
B. Distance
C. Energy
D. Speed
E. Time
F. Volume
Answer:
Distance.
Explanation:
Wavelength (λ) can be defined as the distance between two successive crest or trough of a wave.
From the above definition, wavelength (λ) simply measures distance.
This can further be explained by obtaining the unit of measurement for wavelength (λ).
This can be illustrated below:
Wavelength is related velocity and frequency according to the following equation:
Velocity (v) = wavelength (λ) x frequency (f)
v = λf
λ = v/f
Velocity is measured in ms¯¹
Frequency is measured in hertz, Hz (s¯¹)
λ = v/f
λ = ms¯¹ / s¯¹
λ = m
We can see that wavelength is measured in metre (m) which is the same unit for measuring distance.
Therefore, wavelength measures distance.
If the molarity of sugar is 1.1, what will the freezing point be?
Answer:
The freezing point will be -2.046°C.
Explanation:
The freezing point depression equation is [tex]\Delta T_f = k_f \cdot m \cdot i[/tex]
Where;
[tex]\Delta T_f[/tex] = The temperature depression of the freezing point
[tex]k_f[/tex]= The constant of freezing point depression which is solvent dependent = 1.86°C/m
i = The number of particles the substance decomposes into in solution = 1 for sugar (a covalent compound)
m = The molality of the solution = 1.1
Therefore, we have;
[tex]\Delta T_f = 1.86 \times 1.1 \times 1 = 2.046 ^{\circ}C[/tex]
Therefore the freezing point will be 0 - 2.046°C = -2.046°C.
According to periodic trend, which of the following most likely has the highest ionization energy?
Ca
Mn
Br
Zn
Answer:
Br
Explanation:
Ionization energy increases across a period.
All other elements are ahead in the period as compared to Br.
How are proteins carbohydrates and fats related to the discipline of chemistry
Answer:
Explanation:
The nutrition label on rice lists the amounts of proteins, carbohydrates, and fats in one serving. These substances are important for human nutrition. How are proteins, carbohydrates, and fats related to the discipline of chemistry? All are chemical compounds. All are found in living things. All are needed for nutrition. All are found in non-living things.
The answer for this question would be A) All are chemical compounds.
The answer is All are chemical compounds
Levi decides to examine the effect of fertilizer on the growth of tomato plants. He chooses four plants for his experiment and applies varying amounts of fertilizer to three of them. He does not apply fertilizer to one plant. Over a 15-day period, the plants receive fertilizer on Days 1, 4, 7, 10, and 13. Levi measures the height of all of his plants with a meter stick on days 3, 6, 9, 12, and 15. He also makes sure to hold all experimental factors constant except for the fertilizer.
Where should the independent and dependent variables of Levi's experiment be placed when graphed?
Select all that apply.
the amount of fertilizer;y-axis
plant height;x-axis
the amount of fertilizer;x-axis
plant height; y-axis
Answer:
the amount of fertilizer; x-axis
plant height; y-axis
Explanation:
The independent and dependent variables of Levi's experiment placed when graphed are the amount of fertilizer and the y-axis. Option B is correct.
What are independent and dependent variables?The independent variables are those which are not dependent on other factors for their working or cannot be influenced by any other factor and the dependent variable is just the opposite of this one.
The experiment depends on the height of the plant but the fertilizer is independent of to work of the plant and fertilizer is independent and high and depends on other factors.
Therefore, Option B is correct. independent and dependent variables of Levi's experiment placed when graphed are the amount of fertilizer and the y-axis.
Learn more about independent and dependent variables, here;
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Chemistry deals with all the following except: Select one: a. The composition of matter. b. The properties of matter. c. Our eating habits. d. The conversion of matter between various states.
Answer:
C. Our eating habits
Hope that helps.
HELP ASAP! 50 POINTS! Which type of electromagnetic radiation has a longer wavelength than visible light? (4 points) Gamma rays Infrared radiation Ultraviolet radiation X‒rays
Answer:Infrared radiation
Explanation:just took the test
The electromagnetic radiation that has a longer wavelength than visible light is Infrared radiation.
The electromagnetic spectrum is an arrangement of of electromagnetic waves in order of increasing frequency and energy. We must note the longer the wavelength, the farther it appears towards the left in the electromagnetic spectrum.
The visible spectrum spans between 400 nm - 700 nm in the electromagnetic spectrum. The electromagnetic radiation that has a longer wavelength than visible light is Infrared radiation.
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What is Entropy?
A. The opposite of Enthalpy
B. The temperature at which a reaction is feasible.
C. Free energy used for a reaction.
D. A measure of disorder,
Answer:
D.) A measure of disorder
Explanation:
I got it correct on founders edtell
3.7500 x 104 + 9.7100 x 105
Answer: [tex]1409.55[/tex]
Remove the 0's from each decimal number
[tex]3.7500 ---> 3.75\\9.7100 ---> 9.71[/tex]
Multiply
[tex]3.75*104=390\\9.71*105=1019.55[/tex]
Add
[tex]930+1019.55=1409.55[/tex]
es with hydrogen
atoms
Fill the valencies with
C
+
() C c-c=c
(ii)
(
c
C - C = C
/
c
(ii)
c
- C
با
-
1
c - c
С — С
co
Answer:
all u have to do is inserting hydrogen atoms where it's possible, if carbon is not bonded to any element, then it can have 4 hydrogens. for the first chain, the first carbon can have 3 hydrogen atoms, the second carbon 1 hydrogen atom only the third also 1 hydrogen since there is double bond and the 4th 2 hydrogen atoms
Answer:
a rat and a cat can have sex
xD
Explanation:
The specific heat capacity of a pure substance can be found by dividing the heat needed to change the temperature of a sample of the substance by the mass of the sample and by the change in temperature. The specific heat capacity of a certain substance has been measured to be 3.52 J/g °C. Suppose 420.0 g of the substance is heated until the temperature of the sample has changed by 43.8 °C.
Write an equation that will let you calculate the last Q that was needed for this temperature change. Your equation should contain only symbols. Be sure to define each symbol.
Answer:
The answers to your questions are given below.
Explanation:
Data obtained from the question include:
Mass (M) = 420.0 g
Temperature change (ΔT) = 43.8 °C
Specific heat capacity (C) = 3.52 J/g °C
Heat needed (Q) =...?
The heat needed for the temperature change can be obtained by using the following formula:
Q = MCΔT
Where:
Q is the heat needed measured in joule (J).
M is the mass of substance measured in grams (g)
C is the specific heat capacity of the substance with unit J/g °C.
ΔT is the temperature change measured in degree celsius (°C).
Thus, we can calculate the heat needed to change the temperature as follow:
Q = MCΔT
Q = 420 x 3.52 x 43.8
Q = 64753.92 J
Therefore, the heat needed to cause the temperature change is 64753.92 J
Charles is given two electrical conductors – aluminium and graphite. Help him to select one for making an electric wire. Justify your reason.
Answer:
I think the answer is aluminium because both graphite and Al are good conductors of electricity but Al is more ductile than graphite. also pls mark as Brainilest.
Explanation:
you just got home from a run on a hot Atlanta afternoon. you grab a 1.00-liter bottle of water and drink three-quarters of it in one swig. How many moles of water did you consume?
Answer:
41.67 mol
Explanation:
1 Litre of water = 1000g
Mole = mass / molar mass
Mass of 1 L of water = 1000 g
Molar mass of water (H2O) :
(H = 1, O = 16)
H2O = (1 * 2) + 16 = (2 + 16) = 18g/mol
Amount of water consumed = (3/4) of 1 litre
= (3/4) * 1000g
= 750g
Therefore mass of water consumed = 750g
Mole = 750g / 18g/mol
Mole of water consumed = 41.6666
= 41.67 mol
Naturally occurring magnesium exists as three isotopes. 78.70% is Mg-24 with a mass of 23.98504 amu, 10.13% is Mg-25 with a mass of 24.98584 amu, and 11.17% is Mg-26 with a mass of 25.98259 amu. What is the atomic mass of magnesium?
Answer:
The correct answer is 24.31 amu.
Explanation:
The formula for finding the average atomic mass = The sum of the percentage abundance of isotopes × the actual mass of isotopes
The average atomic mass = % abundance of Mg-24 × actual mass + % abundance of Mg-25 × its actual mass + % abundance of Mg-26 × its actual mass
Avg. Atomic mass = 0.7870 × 23.98504 + 0.1013 × 24.98584 + 0.1117 × 25.98259
Avg. atomic mass = 18.88 + 2.53 + 2.90 = 24.31 amu
The atomic mass of magnesium is 24.31 amu.
A chemical equation is balanced when Group of answer choices the number of atoms of each element is the same in reactants and products. the charge on each atom is the same in reactants and products. the sum of the coefficients of the reactants is equal to the sum of the coefficients of the products. the total number of ions is the same in reactants and products. the total number of molecules is the same in reactants and products.
Answer:
a
Explanation:
A chemical equation is said to balanced only when the number of atoms of each element is the same in both reactants and products side. Rest all options are absurd. Hence, option a is correct.
Balancing of the reaction has no relation with coefficient, molecules or charge of the elements
In the lab, Amanda has two solutions that contain alcohol and is mixing them with each other. She uses twice as much Solution A as Solution B. Solution A is 11% alcohol and Solution B is 18% alcohol. How many milliliters of Solution B does she use, if the resulting mixture has 320 milliliters of pure alcohol?
Answer:
1,103.47 milliliters
Explanation:
The total percentage of alcohol from solution A and solution B is 29. In a solution that is a mixture of solution A and B, the percentage of alcohol that would be contributed by solution A would be:--
11/29 x 100% = 37.93%
--while the percentage of alcohol that would be contributed by solution B would be:
18/29 x 100 = 62.07%
Hence, if a mixture of A and B has 320 milliliters of alcohol, the amount of alcohol contributed by B would be:
320 x 62.07/100 = 198.624 milliliters
Now, remember that solution B is 18% alcohol. This means that the 18% alcohol content of solution B is 198.624 milliliters. Thus, the total volume of solution B would be:
198.624 x 100/18 = 1,103.47 milliliters.
Therefore, the total milliliters of solution B Amanda used would be 1,103.47.
How many moles are present in 136 grams of MgCl2? 1.46 mol 1.43 mol 2.27 mol
Answer:
1.43 mol
Explanation:
How do I know if CsBr in water is an acid, base or neutral? And how do I show it with a balanced equation
Answer:
Neutral
Explanation:
We can consider this salt as a neutral one. It can be prepared by a neutralization reaction between the base and the acid.
CsOH + HBr → H₂O + CsBr
As the two reactants are strong, the HBr as a strong acid, and the CsOH as a strong base, the ions are considered as: the weak conjugate acid and the weak conjugate base.
Br⁻ + H₂O ← HBr + OH⁻
Cs⁺ + H₂O ← CsOH + H⁺
They can not react to water, that's why the salt is neutral (similar as the NaCl)
pH = 7
For the set of ionic compounds, CaSO4, CaCO3, Ca(OH)2, choose the correct characterization of their solubilities in water from the response list. Group of answer choices None of the three salts are soluble. All three salts are soluble. Two of the three salts are soluble. One of the three salts is soluble.
Answer:
None of the three salts are soluble.
Explanation:
According to the solubility rule, the carbonates and sulphates of group two elements are insoluble in water.
All three substances mentioned possess very low solubility in water and can be said to be slightly soluble in water. If we compare them with other ionic substances that dissolve readily in water, we can rightly say that they are insoluble in water.
Hence all three substances are insoluble in water.
