Which of the following is not a characteristic of both experiments and
surveys?
A. Subjects should be randomly selected.
B. The data collected might be studied for patterns.
C. The researcher exercises direct control over at least one variable.
D. Data are collected about a population.
Answer:
C. The researcher exercises direct control over at least one variable.
Explanation:
Your answer should be C. The researcher exercises direct control over at least one variable.
I hope it helps! Have a great day!
pan~
A sample has 0.2 moles of salt dissolved in 2 L of solution. What is the molarity
The molarity of the sample of the salt dissolved in the solution is determined as 0.1 M.
What is the molarity of the sample?
The molarity of the sample is the number of solutes dissolved in liters solution.
molarity = number of moles/Liters of solution
molarity = 0.2 moles / 2L
molarity = 0.1 M
Thus, the molarity of the sample of the salt dissolved in the solution is determined as 0.1 M.
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What is the heat capacity equation?
Answer:
The specific heat capacity is the heat or energy required to change one unit mass of a substance of a constant volume by 1 °C. The formula is Cv = Q / (ΔT ⨉ m)
What is the mass in kilograms of a sample containing 2.4 x 10^{24} atoms of this element? Do not use scientific notation.
What type of reaction is this?
Na(s) + O2(g)
Answer:
Combustion. It is combustion since we assume that it is in a rigid container and Na reacts with oxygen gas
A way of generating dry O2 in the lab is to heat potassium chlorate. If you determined that 25 grams of O, are needed, how much potassium chlorate do you need to start with? 2KCI0, ->(heat)2KCI + 30,
Answer:
About 64 grams of KClO₃.
Explanation:
Potassium chlorate dissociates according to the equation:
[tex]\displaystyle 2\text{KClO$_3$} \xrightarrow{\text{heat}} 2\text{KCl} + 3\text{O$_2$}[/tex]
To determine the amount of KClO₃ necessary to produce 25 grams of O₂, we can convert grams of O₂ to moles; moles of O₂ to moles of KClO₃; and finally to grams of KClO₃.
The molecular weights of O₂ and KClO₃ are 16.00 g/mol and 122.55 g/mol.
Hence:
[tex]\displaystyle 25\text{ g O$_2$} \cdot \frac{1\text{ mol O$_2$}}{32.00\text{ g O$_2$}} \cdot \frac{2\text{ mol KClO$_3$}}{3\text{ mol O$_2$}} \cdot \frac{122.55\text{ g KClO$_3$}}{1\text{ mol KClO$_3$}} = 64\text{ g KClO$_3$}[/tex]
In conclusion, about 64 (to two significant digits) grams of KClO₃ is needed.
The pressure of a nitrogen gas, N2, cylinder is measured at 250 K and found to be 4.0 atm. What is the pressure of the same cylinder at room temperature, 293 K?
Apply Gay lussac's law
P_1T_2=P_2T_14(293)=250P_21172=250P_2586=125P_2P_2=586/125P_2=4.688atm25 points!!! What’s the answer???
Answer:
C
Explanation:
Cause wave's get larger and larger and it will repeat over and over
(please mark me brainly est)
Which molecule would provide the most accurate value for the bond length of a nitrogen-nitrogen double bond
Answer:
i dont know, i wish i could help
Explanation:
What is the volume occupied by 11 grams of NO2(g) at STP?
Please Help I don’t understand
The volume of gas occupied by 11 grams of nitrogen dioxide gas at STP is 5.15 L.
What is the ideal gas equation?Ideal gas equation of any gas will be writen as:
PV = nRT, where
P = standard pressure = 1 atm
V = volume = ?
R = universal gas constant = 0.082 L.atm/K.mol
T = standard temperature = 273K
n is the moles of gas which can be calculated by using below equation as:
n = W/M, where
W = given mass = 11g
M = molar mass = 46 g/mol
n = 11 / 46 = 0.239mol
On putting values on the above equation, we get
V = (0.23)(0.082)(273) / (1) = 5.15 L
Hence required volume of gas is 5.15 L.
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By examining electron domain geometry, one can determine that the ammonia molecule (NH3) has
Answer:
The ammonia molecule is a trigonal pyramidal and has 4 sp3 orbitals
Explanation:
Nitrogen has 5 valence electrons, Hydrogen takes up 3 bonds and there's a lone pair on top, and the gemoetry is structured in a way so the hydrogen atoms are facing down away from the lone pair and evenly spaced out between the other hydrogens.
Which are produced when HCl reacts with Ca(OH)2?
Cl2, H3, and CaO
CaCl and H3O
CaO, Cl2, and H2O
CaCl2 and H2O
Answer:
b did the test
Explanation:
did the test
A balanced chemical equation obeys the law of conservation of mass. The reaction of HCl with Ca(OH)₂ is a weak base - strong acid reaction. The products formed are CaCl₂ and H₂O. The correct option is D.
What is a balanced chemical equation?A chemical equation in which the number of reactants and products on both sides of the equation are equal is defined as the balanced chemical equation. The coefficients are the numbers which are added to balance the chemical equation.
The balanced equation for the reaction of HCl with Ca(OH)₂ is given as:
Ca (OH)₂ (s) + 2HCl (aq) → CaCl₂ (aq) + 2H₂O (l)
Here one mole of Ca (OH)₂ reacts with two moles of HCl and gives one mole of CaCl₂ and two moles of H₂O respectively. Here Ca (OH)₂ is a white precipitate and HCl is a aqueous solution.
Thus the correct option is D.
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Section 1
1. The Florida scrub jay is a bird found only in the scrub habitat of Central Florida. Efforts are being ma
in Florida to preserve the scrub habitat by limiting development by humans and maintaining natural
conditions. Which may occur over time if the Florida scrub habitat is NOT preserved? (SC.5. L.15.1)
A. The scrub jays may become extinct.
B. The scrub jays may move to live in a coastal habitat.
C. The scrub jays may learn to live in any habitat that replaces the scrub habitat. X
D. The scrub jays may have offspring with changed features to match a new habitat.
Answer:
i belive it is A
Explanation:
well if it olny lives in those scrub habitats and the habitats get desroyed or polluted they will no longer be habitable there fore causeing the scrub jay to go exctinct.
Find the pH of a 0.600 M solution of methylamine CH3NH2. Kb= 4.4 x 10^-4
chemistry question, 20 points, will mark as brainliest if correct:
Answer:
CS2 + 3O2 -> CO2 + 2SO2
Explanation:
Which feature of the state means absolute authority within the country?
Sovereignty is the ultimate authority, in the decision-making process of the state and in the maintenance of law and order.
What is sovereignty?Sovereignty refers to authority within an individual consciousness or territory. Sovereignty entails hierarchy within the state and also for external autonomy for states.
So we can conclude that sovereignty is the ultimate authority, in the decision-making process of the state and in the maintenance of law and order.
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Choose all the answers that apply.
The troposphere is _____.
the warmest layer
responsible for weather and clouds
the coldest layer
warmed by the Earth's surface
the lowest layer
Answer:
The lowest layerWarmed by earth surfaceExplanation:
Troposphere is the lowest layer located on atmosphere of earthIt contains all green house gases so it becomes warmed by reflection of heat from earth surfaceAnswer:
warmed by the Earth's surface
the lowest layer
Explanation:
What percentage of Americans believes that humans are causing global warming?
10
24
68
93
Answer:
49% say human activitiy contributes global warming.
Answer:
The answer is 68%
Explanation:
including me :)
Magnesium ribbon with a mass of 2g was placed into dilute hydrochloric acid. The
equation for this reaction is:
Mg(s) + 2HCI = MgCl2(aq) + H2(g)
The magnesium ribbon reacted and completely disappeared in 30 seconds. Calculate
he rate of reaction.
The rate of reaction of the magnesium ribbon in the dilute hydrochloric acid is 0.067 g/s.
What is rate of reaction?
Rate of reaction is the rate at which a reaction takes place. It is proportional to the increase in the concentration of a product per unit time and to the decrease in the concentration of a reactant per unit time.
Mg(s) + 2HCI = MgCl2(aq) + H2(g)
Rate of reaction = mass of magnesium reacted/time taken
Rate of reaction = 2 g /30 s
Rate of reaction = 0.067 g/s
Thus, the rate of reaction of the magnesium ribbon in the dilute hydrochloric acid is 0.067 g/s.
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25 points!!!! What’s the answer???
Explanation:
Constructive interference occurs when the maxima of two waves add together (the two waves are in phase), so that the amplitude of the resulting wave is equal to the sum of the individual amplitudes. Equivalently, the minima of the waves would be aligned.
In the reaction of nitrogen gas, N2, with hydrogen gas, H2, to form ammonia gas, NH3 , how many moles of hydrogen are needed to react with two moles of nitrogen
Answer:
6 moles
Explanation:
First find the balanced equation for the rxn
N2 + 3 H2 ===> 2 NH3
each mole of N2 requires 3 moles of Hydrogen
so 6 moles of H needed
How much time would it take for 40000 atoms of sodium-24 (half-life is 15 days) to decay to 2500 atoms?
Answer:
60 days
Explanation:
2500 = 40000 ( 1/2) ^n
n = 4 half lives
4 half lives * 15 days/ halflife = 60 days
If you put 5ml of coffee into 15ml of water how much was the coffee diluted
For 5ml of coffee into 15ml of water, the dilution of the coffee is mathematically given as
X=0.25ml
Generally, the equation for the Total volume is mathematically given as
Tv =inital v+final volume
Therefore
Tv=5ml+15ml
Tc=20ml
In conclusion, Ther extent of diluti\on is
X=5/20ml
X=0.25ml
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A manufacturer advertises that a particular brand of lotion is “pH balanced” and that it has a pH equal to 6.25. What can you infer about the lotion based on the information in the ad?
We can infer about the given information of lotion is that pH is slightly acidic in nature.
What is pH?pH of any solution gives idea about the acidity or basicity of that solution, and it will be calculated as:
pH = -log[H⁺]
pH value in the range of 0 to 6.9 shows acidity, 7 shows the neutral nature and from 7.1 to 14 shows basicity. Given pH value of lotion i.e. 6.25 states that lotion is slightly acidic in nature.
Hence pH value of lotion informs that lotion is slightly acidic.
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2.
The simile in stanza 1 (lines 1-6) helps show the speaker -
wants to learn different languages in order to communicate with others
feels torn between two different worlds that have little in common
wants to go home again and not have to speak or listen to anyone
feels annoyed by having to spend so much time listening to others
The simile in stanza 1 (lines 1-6) shows that the speaker:
"feels torn between two different worlds that have little in common" (Option B)
Why does the speaker feel torn between two different worlds?
She speaker feels torn between two different worlds because the two worlds speak different languages.
It is to be noted that a simile is a figure of speech that compares two different things making use of the word "as".
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How many grams of potassium iodide (KI) are required to prepare 50 mL of a 0.30 M
solution?
Answer:
137 g
Explanation:
Since1 L=103 mLyou can say that your sample must contain 550.0mL solution⋅1.50 moles KI103mL solution=0.825 moles KITo convert the number of moles of potassium iodide to grams, use the molar mass of the compound.0.825moles KI⋅166.003 g1mole KI=137 g−−−−−
which words in the story help the reader understand the meaning of the word avid in paragraph 1?
The curious and observant are the words in the story which helps the reader understand the meaning of the word avid.
What is Avid?This refers to when an individual is very enthusiastic or interested in something.
In paragraph 1 , the words which makes us understand the word 'avid' is the character being curious and observant which shows there is interest.
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Some landforms you might see while traveling across the country could be
mountains
forests
hills
rivers
glaciers
Answer:
Mountains, Hills and Rivers
Explanation:
Because I read it and I already know that
Hope that helps!
Answer:
Mountains, Hills and Rivers
Explanation:
Why the positive emulsion for bread is not clear?
A compound has a mass percent composition of 58.8% C, 9.86% H and 31.32% O. The molar mass of the compound is 306.39 g/mol.
(a) Calculate the empirical formula.
(b) Calculate the molecular formula
Enter your answers using the following format for a formula: C3H3O3
The solution would be like this for this specific problem:
Moles of carbon = 58.8 / 12 = 4.9
Moles of hydrogen = 9.8 / 1 = 9.8
Moles of oxugen = 31.4 / 16 m= 1.96
Ratio 4.9 / 1.96 = 2.5 9.8 / 1.96 = 5.0 1.96 / 1.96 = 1
Simplest formula = C5H10
I hope this helps and if you have any further questions, please don’t hesitate to ask again.