Answer:
Observational study
Explanation:
An investigation of what happened over the years to the people who were exposed to radiation during the 1986 Chernobyl nuclear disaster would be termed an observational study because it will require observing subjects and finding out if there is a kind of correlating factor in the subjects that could indicate the level of exposure to the nuclear radiation.
There are basically two types of research studies:
1. Observational studies
2. Experimental studies
Observational studies involve just the observation of subjects and trying to find out some correlation factors. This kind of study could be prospective when it deals with what could happen in the future based on certain factors or retrospective when it considers what has already happened. An observational study can be cross-sectional, case-only, case-control, or cohort study.
Experimental studies are also referred to as randomized or controlled trial studies. Here, subjects are grouped and each group receives a different treatment in order to isolate the effect of a particular factor or variable relating to the treatment.
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Answer:
I play!!!!!!!!
Explanation:
A gas at -20c occupies volume 140 ml calculate temperature at which the volume of the gas becomes 65 ml pressure constant
Answer:
–156 °C
Explanation:
The following data were obtained from the question:
Initial temperature (T1) = –20 °C
Initial volume (V1) = 140 mL
Final volume (V2) = 65 mL
Final temperature (T2) =?
Pressure = constant.
Next, we shall convert –20 °C to Kelvin temperature. This can be obtained as follow:
T(K) = T(°C) + 273
Initial temperature (T1) = –20 °C
Initial temperature (T1) = –20 °C + 273 = 253 K.
Next, we shall determine the new temperature of the gas as follow:
Initial temperature (T1) = 253 K
Initial volume (V1) = 140 mL
Final volume (V2) = 65 mL
Final temperature (T2) =?
V1/T1 = V2/T2
140/253 = 65/T2
Cross multiply
140 × T2 = 253 × 65
140 × T2 = 16445
Divide both side by 140
T2 = 16445 /140
T2 = 117 K
Finally, we shall convert 117 K to celcius temperature. This can be obtained as follow:
T(°C) = T(K) – 273
T2 = 117 K
T2 = 117 K – 273
T2 = –156 °C
Thus, the new temperature of the gas is –156 °C
Determine the molarity of a solution prepared by dissolving 0.198 g of "KHP" (C8H5O4K) in enough water to make 125 mL of solution.
When the solution is found and titrated with aqueous sodium hydroxide, the endpoint is reached after the addition of 27.80 mL of base solution. How many moles of NaOH reacted? What is the concentration of the NaOH?
Answer:
0.007756M KHP; 0.0009695 moles NaOH reacts; 0.03488M NaOH.
Explanation:
Potassium hydrogen phthalate, KHP, is a salt used as standard to determine concentration of basic solutions as NaOH solutions.
To find molarity of the KHP solution we need to convert mass of KHP to moles and divide this in 125mL = 0.125L:
Moles KHP -Molar mass: 204.22g/mol-:
0.198g * (1mol / 204.22g) = 0.0009695 moles KHP
Molarity:
0.0009695 moles KHP / 0.125L = 0.007756M KHP
NaOH reacts with KHP as follows:
NaOH + KHP → Na⁺ + KP⁻ + H₂O
That means 1 mole of NaOH reacts per mole of KHP, that means moles of NaOH that reacts are = Moles of KHP added:
0.0009695 moles NaOH reacts
In 27.80mL = 0.02780L the NaOH was contained. Molarity is:
0.0009695 moles NaOH / 0.02780L =
0.03488M NaOH
Moles of NaOH added will be "0.034".
According to the question,
→ [tex]Molarity = \frac{Number \ of \ moles}{Volume}[/tex]
By substituting the values, we get
[tex]= \frac{0.198}{204}\times \frac{1000}{125}[/tex]
[tex]= 0.0077 \ M[/tex]
Let,
The number of moles added be "[tex]M_2[/tex]".Now,
→ [tex]M_1 V_1 = M_2 V_2[/tex]
→ [tex]0.0077\times 125=M_2\times 27.8[/tex]
→ [tex]M_2 = 0.034 \ moles[/tex]
Thus the above answer is appropriate.
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In a titration, you start with 0.05 M sodium hydroxide (NaOH) and slowly add it to 40 mL of HC1 with an unknown concentration. What is the original concentration of the HC1 if you add a total of 15.4 mL of sodium hydroxide to the HC1 to achieve pH =7?
Answer:
The original concentration of the HCl is: 0.01925 M
Explanation:
Equation:
HCl+NaOH-------> NaCl+H₂O
Volume of NaOH added = 0.05 M
No of moles of NaOH = 15.4 mL [tex]x\frac{1 L}{1000 mL} x\frac{0.05 mol NaOH}{L}[/tex]
= 0.00077 mol NaOH
Then,
Volume of HCl solution = 40 mL x 1/1000 mL
= 0.0400 L
Therefore,
Concentration of HCl = 0.00077 mol/0.0400 L
= 0.01925 M
Now, to find the pH:
pH = -log₁₀[H⁺]
= -log₁₀(2x10⁻⁶)
= 5.7
How many atoms of phosphorus are in 5.70 mol of copper(II) phosphate?
Answer:
Cu3 (PO4)2 contains a total of 2 atoms of phosphorus in just one molecule. (2.10 mol)(6.02214 x 10^23 atoms / mol)(2 phosphorous) = 2.53 x 10^24 atoms of phosphorous per molecule of copper i
Explanation:
Many materials, such as rocks, expand (get larger) when they are heated and contract (shrink) when they are cooled. This change
in size can cause cracks to form and break large rocks into smaller pieces.
In this example, what is caused by heating and cooling?
OA. decay
ОВ.
weathering
OC.
erosion
OD
earthquakes
Answer:
OB: weathering
Explanation:
the cycle of heating and cooling causes stresses called thermal fatigue, this causes the material to break down. In hand, weathering is a physical and chemical process that causes rocks and minerals on the Earth's surface to break down and decompose. Therefore, this matches the process you have described.
Answer:
weathering fun way to imagen it: just imagen u saw ur worst enemie and pretende it is the rock and the wind and ice and water are ur best friends THEN BAM wind and ice and water(ur best friends) make the rock(worst enemie) to dust :D
Sugar and Salt in water magnetism, state of matter, or solubility?
please help!!!!
Answer:
solubility
Explanation:
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A weather balloon with a volume of 3.40774 L
is released from Earth’s surface at sea level.
What volume will the balloon occupy at an
altitude of 20.0 km, where the air pressure is
10 kPa?
Answer in units of L.
Answer: The volume occupied at an altitude of 20.0 km is 34.5289 L
Explanation:
Boyle's Law: This law states that pressure is inversely proportional to the volume of the gas at constant temperature and number of moles.
[tex]P\propto \frac{1}{V}[/tex] (At constant temperature and number of moles)
where,
[tex]P_1[/tex] = initial pressure of gas = 101.325 kPa ( sea level)
[tex]P_2[/tex] = final pressure of gas = 10 kPa
[tex]V_1[/tex] = initial volume of gas = 3.40774 L
[tex]V_2[/tex] = final volume of gas = ?
Now put all the given values in the above equation, we get the final pressure of gas.
[tex]101.325\times 3.40774=10\times V_2[/tex]
[tex]V_2=34.5289L[/tex]
Therefore, the volume occupied at an altitude of 20.0 km is 34.5289 L
how many atoms does sodium hypochlorite have?
Answer:
NaClO; the contained elements ae Na, Cl, O.
Three isotopes of argon occur in nature. Calculate the average atomic mass of argon given the following relative atomic masses and abundances of each of the isotopes.
Isotope Relative Atomic Mass Abundance
Ar-36 35.97 amu 0.337%
Ar-38 37.96 amu 0.063%
Ar-40 39.96 amu 99.600%
a
35.97 amu
b
37.95 amu
c
39.95 amu
d
38.96 amu
Answer:
whats the question
Explanation:
Answer:
Calculate the average atomic mass of argon to two decimal places, given the following relative masses and abundances of each of the isotopes: argon-36 (35.97 amu; 0.337%), argon-38 (37.96 amu; 0.063%), and argon-40 (39.96 amu; 99.600%). ... So the atomic mass of Ar is 0.99639. 96 + 0.0006337. 96 + 0.00337*35.97 = 39.957.
Explanation:
hope this help
Toluene is subjected to the action of the following reagents in the order given: (1) KMnO4,OH-, heat; then H3O (2) HNO3, H2SO4 (3) Br2, FeBr3 What is the final product of this sequence?
Answer:
See image attached
Explanation:
The reaction of toluene with alkaline potassium permanganate in the presence of heat leads to the oxidation of the -CH3 to give benzoic acid.
Reaction benzoic acid with HNO3/H2SO4 yields the nitronium ion (NO2+).
Recall that -COOH is a metal director and deactivated the ring towards electrophilic substitution hence the m-nitrobenzoic acid is formed.
Reaction with FeBr3/Br2 yields the product shown in the image attached.
Balance the following equations ___Fe + __O2= ___Fe3O4
Elements in the same period have _____ in common?
-
Answer:
The elements that have the same number of energy levels or the orbitals.
Explanation:
They have he same number -- energy levels
What name is given to the elements that appear in the right-most column of the periodic
table?
- Alkali metals
- Alkaline earth metals
- Transition metals
- Noble gases
(NOBLE GASES IS ANSWERR)
Answer:
Noble gases... (You already know...)
Explanation:
The right-most column of the periodic table contains atoms with full electron shells, also known as Noble Gases.
Hope this helped!
Answer:
Noble gases
Explanation:
The six elements listed in the last column of the table (Group 18) of the periodic table are collectively referred to as the noble gases. All of the noble gases have the maximum number of electrons possible in their outer shells (two electrons in helium’s outer shell, and eight electrons for all the others), making them stable.
Weathering is a constructive process.
True or false
Answer: true
Explanation: Collection and analysis of data indicates that constructive forces include crustal deformation, faulting, volcanic eruption and deposition of sediment, while destructive forces include weathering and erosion.
what reacts at room temperature with ethanol and also with ethanoic acid
Answer: Its esterification reaction.
when organic acid react with alcohol it forms ester and water. reaction is known as esterification reaction.
CH3COOH + C2H5OH → CH3COOC2H5 + H2O
ethanoic acid + ethanol → ethyl acetate + water
this reaction takes place in the presence of acid catalyst ( dil H2SO4).
in this reaction oxygen of ethanol with lone pair act as nucleophile and carbonyl carbon of acetic acid act as electrophile.. so its nucleophilic substitution reaction of -COOH group.
Explanation:
Which of these lead (II) salts will dissolve to the greatest extent in water?
a. PbSO4, Ksp = 1.7x10^-8
b. PbI2, Ksp = 6.5x10^-9
c. PbCrO4, Ksp = 1.8x10^-14
d. PbS, Ksp = 2.5x10^-27
e. Pb3(AsO4)2, Ksp = 4.0x10^-36
Answer:
a. PbSO4, Ksp = 1.7x10^-8.
Explanation:
Hello!
In this case, since the solubility product indicates how likely a solid is able to ionize and consequently dissolve in water, we can infer that the larger the solubility product Ksp, the more ions are able dissolve in water; therefore the proper answer goes with the largest Ksp, which is a. PbSO4, Ksp = 1.7x10^-8 since the power goes closer to 1 than the other options.
Best regards!
A compound of copper and sulfur contains 76.84 g of metal and 38.53 g of nonmetal. How many grams of copper are in 3801 kg of the compound? How many grams of sulfur?
Answer:
There are:
2'531,500 g Cu1'269,500 g SExplanation:
First calculate the percentage of Cu and S in the compound:
Total mass = 76.84 g + 38.53 g = 115.37 g% metal (Cu) = 76.84/115.37 * 100% = 66.6%% metal (S) = 38.53/115.37 * 100% = 33.4%These percentages will remain the same no matter how much of the compound we analyze.
Now we calculate the grams of Cu and S in 3801 kg of the compound:
kg Cu = 3801 kg * 66.6/100 = 2531.5 kg Cug Cu = 2531.5 kg * 1000 = 2531500 g Cukg S = 3801 kg * 33.4/100 = 1269.5 kg Sg S = 1269.5 kg * 1000 = 1269500 g SWhat is the answer? Please
Answer:
Cell
Explanation:
I just passed this unit a month ago.
Answer:
It is 6. Cell
Explanation:
Cells make up the smallest level of a living organism such as yourself and other living things. The cellular level of an organism is where the metabolic processes occur that keep the organism alive. That is why the cell is called the fundamental unit of life.
I really hope this helped. God bless you and have a great day! :-)
The properties of compund are different from the properties of their constituenr
Answer: Atoms of carbon and hydrogen
Explanation:
Which process is shown in the diagram?
0,
ing
CO, +H,0
Chloroplast
Mitochondrion
Sugar
Heat
o
ATP
Respiration
The cellular respiration process, which generates ATP as the final result, employs oxygen and sugar as reactants. So, the correct option is A.
What is Cellular respiration?Cellular respiration is the process by which organisms combine oxygen with food molecules, channeling the chemical energy from those resources into life-sustaining activities while eliminating carbon dioxide and water as waste.
Both oxygen and glucose are reactants in the mobile respiratory system. ATP is the primary component of mobile respiration; waste products include carbon dioxide and water.
Oxygen might be present or absent while cells are respiring. Nonetheless, the activity is essentially known as "cellular respiration" because the cell seems to "respire" by consuming molecular oxygen (as an acceptor of electron) and exhaling carbon dioxide (as an end product).
Therefore, the correct option is A.
Learn more about Cellular respiration, here:
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Your question is incomplete, most probably the complete question is:
The process shown in the diagram produces oxygen and sugar. Which
process uses oxygen and sugar as reactants?
Chloroplast
Mitochondrion
Sugar
CO, +H,0
ATP
Heat
Respiration
A. Cellular respiration
B. Water cycle
c. Transpiration
D. Photosynthesis
Every element in group one has ______________ electron in its outer shell. Every element in group two has _______________ electrons in its outer shell.
need help
What is the difference between Mega and Milli symbols?
Answer:
Mega = 10^6
Milli = 10^-3
Explanation:
Mega is whatever times 10 to 6th power.
Milli is whatever times 10 to the -3rd power.
A competitive high school swimmer takes 56.7 seconds to swim 100. yards. What is his rate in m/min?
m
min
Answer:
96.72 m/min
Explanation:
The following data were obtained from the question:
Time (t) = 56.7 s
Distance (d) = 100 yard
Rate (R) =?
Next, we shall convert 56.7 s to minutes. This can be obtained as follow:
60 s = 1 min
Therefore,
56.7 s = 56.7 s × 1 min /60 s
56.7 s = 0.945 min
Next, we shall convert 100 yard to metre (m). This can be obtained as follow:
1 yard = 0.914 m
Therefore,
100 yard = 100 yard × 0.914 m /1 yard
100 yard = 91.4 m
Finally, we shall determine the rate of the swimmer as follow:
Time (t) = 0.945 min
Distance (d) = 91.4 m
Rate (R) =?
R = d/t
R = 91.4/0.945
R = 96.72 m/min
Thus the rate of the swimmer is 96.72 m/min
Mr. Juan is husband of Maria, before they get married Maria knows that her husband cannot make a baby since he cant produce sperm. But during their 2 years in marriage, Maria got pregnant. Is Juan can file a case to Maria? What it is? Support your answer?
Answer:
yes but first he need to check himself
Explanation:
bcoz if he cannot produce a sperm than she might have cheated him and the baby might be of someone other.
in which beakers are the particles moving the most slowly
Answer:
A and D
Explanation:
A scientist performs an experiment involving the collision of two masses on a flat surface. She believes she has made a startling discovery: the total kinetic energy is not conserved. What might she have overlooked?
A.
Some gravitational potential energy may have been gained.
B.
Some gravitational potential energy may have been lost.
C.
Some energy may have been gained due to friction and/or sound.
D.
Some energy may have been lost due to friction and/or sound.
Answer:
c
Explanation:
A rigid container filled with a gas is placed in ice (ex. nalgene bottle). What will happen to the pressure of the gas? What do you think will happen to the volume?(Graph)
Explanation:
The pressure will decrease but the volume remains constant
H20+ SO3 ? Which compound is likely produced by the chemical reaction?
Answer:
h2so4
Explanation:
im big brain.
What does this passage explain about people?
why mothers favor some children over others
the contrasting sides of human nature
why there is harmony in all things
left- and right-handedness
Answer:
the contrasting sides of human nature
Explanation:
I took the test