Evidence that water was once present on a planet is evidence that the planet may once have had living organisms. When landforms on different rocky planets look similar, it is evidence that they may have been formed by the same geologic process. The channel on Mars may have been caused by flowing water or flowing lava.
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Answer:
read the story
Explanation:
read it and then you will find the answer
từ một dung dịch có pH=7 muốn tạo thành dung dịch có pH nhỏ hơn 7 thì cho vào dung dịch
Answer:
you lift my feet off the ground spin me around you make me crazier crazier
All of the following are properties of molecular compounds except
O A A crystal structure,
O B. low melting points.
C. bonds formed through shared electrons,
D. the inability to conduct electric current when melted or dissolved in water,
Answer: the answer is c.
Explanation:
i juss guessed and it was right?
HELP ME OUT PLEASE!!!!
Which statement correctly describes one of the changes?
A) Picture I shows a chemical change, because a new substance is formed.
B) Picture Il shows a chemical change, because a new substance is formed.
C) Picture I shows a chemical change, because the same substance changes form,
D) Picture Il shows a chemical change, because the same substance changes form.
Answer:
Answer D. Picture II shows a chemical change, because the same substance changes form
Explanation:
This is the temperature that water molecules slow down enough to stick to each other and form a solid crystal
Answer:
D Im 90% Sure
Explanation:
If its not right i owe you one I did this one before
Complete and balance the following redox reaction in basic solution
Cr2O7^2-(aq) + Hg(l) ----> Hg^2+(aq) + Cr^3+(aq)
Answer:
balanced in ACID not BASE
Cr2O7^2-(aq) +3Hg(l) +14 H^1+ ----> 3Hg^2+ + 2Cr^3+(aq) + 7H2O
Answer
Cr2O7^2-(aq) +3Hg(l) +14 H^1+ ----> 3Hg^2+ + 2Cr^3+(aq) + 7H2O
Explanation:
Cr2O7^2-(aq) + Hg(l) ----> Hg^2+(aqH) + Cr^3+(aq)
add H^1+ (acid) to capture the O and make 7 water molecules
Cr2O7^2-(aq) + Hg(l) + H^1+ ----> Hg^2+(aqH) + Cr^3+(aq) + 7H2O
Cr goes from +6 to +3 by gaining 3 e
Hg goes from 0 to +2 by losing 2 e
we need 3 Hg for every 2 Cr
so
Cr2O7^2-(aq) +3Hg(l) +14 H^1+ ----> 3Hg^2+ + 2Cr^3+(aq) + 7H2O
2 Cr on the right and left
Net 12 positive charges on the right and the left
3 Hg on the right and left
14 H on the right and left
the equation is balanced
we cannot balance the equation in a basic solution with OH^1-
we have plenty of O in the dichromate ion. we need to convert it to water which take free H^1+ from the acid
1: Given that Ka for HCOOH is 1.8×10^-4 at 25°C what is the value of b for COOH− at 25 °C?
Kb=
2: Given that b for (CH3)2 NH is 5.4×10^-4 at 25°C, what is the value of Ka for (CH3)2NH+2 at 25 °C?
Ka=
Explanation:
At 25 °C Dissociation constant of water or Kw = 1× 10^-14 mol2dm-6
Ka × Kb = Kw for all diluted solutions
Ka×Kb = 1 × 10^-14 mol2dm-6
Therefore for question 1 -
COOH- is the conjugate base for HCOOH ( we find the conjugate base by removing an H atom and the Conjugate acid by adding an H atom)
COOH- (aq) + H2O ( l) <-----> HCOOH( aq) + OH-(aq)
So we can apply the above mentioned equation to find Kb value for COOH-
Kb = 5.56 × 10^-11 moldm-3
For question 2-
We can see that (CH3)2NH+2 is the conjugate acid of (CH3)2 NH. (A H atom has been removed so the one with a H atom less is the conjugate base.)
(CH3)2NH+2 (aq) + H2O (l) <-----> (CH3)2 NH (aq) + H3O+ (aq)
So applying the previously mentioned equation we get Ka = 1.85 × 10^-11 moldm-3
What would be the freezing point of a solution that has a molality of 1.506 m which was prepared by dissolving biphenyl (C12H10) into naphthalene
The freezing point of a solution prepared by dissolving biphenyl (C12H10) into naphthalene is 67.99oC.
Freezing point can be obtained from;
ΔT = K m i
ΔT = freezing point depression
m = molality of the solution = 1.506 m
i = Van't Hoff factor = 1 for molecular substances
K = Freezing constant of naphthalene = 8.15 oC/m
ΔT = 8.15 oC/m × 1.506 m × 1 = 12.27oC
Freezing point of pure naphthalene = 80.26 °C
ΔT = Freezing point of pure naphthalene - Freezing point of solution
Freezing point of solution = Freezing point of pure naphthalene - ΔT
Freezing point of solution = 80.26 °C - 12.27oC = 67.99oC
Learn more:
Convert the heat of neutralization of acetic acid from -49,8 kj/mmol to calories per
millimole and ROUND TO ONE DECIMAL PLACE (1 cal = 4.184 J)
DO NOT INCLUDE UNITS
This question is providing the exothermic heat of neutralization of acetic acid in units of kilojoules per mollimole (-49,8 kj/mmol) and asks for the same value but in calories per millimole which results -11,902.5 cal/mmol.
In this case, according to the given problem, it turns out necessary to solve a two-factor conversion in order to convert the kilojoules to joules and finally to calories as shown below:
[tex]-49.8\frac{kJ}{mmol}*\frac{1000J}{1kJ}*\frac{1cal}{4.184J}[/tex]
Thus, we cancel out the kJ and J, to obtain the following result, rounded to one decimal place:
[tex]-11,902.5\frac{cal}{mmol}[/tex]
Learn more:
https://brainly.com/question/2731380https://brainly.com/question/2921187If 5 g of sodium chloride saturates 12.5 g of water at 10 °C, what mass of sodium chloride would saturate 50 g of water at constant temperature?
Explanation:
since 5g saturates 12.5g of water at 10°c
so......x would saturate 50g of water at 0°c
then you can cross multiply
4
Fe
(
III
)
+
3
O
2
→
2
F
e
2
O
3
Answer:
230293
Explanation:
4fe(lll) + 3o2 2o2 2Fe 2O3 + 230293
What will happen to the temperature of an object if the kinetic energy of the particles increases?
The temperature of an object will increase if the kinetic energy of the particle increases.
Kinetic energy is an energy that is said to be in motion. According to the kinetic molecular theory of ideal gas, the particles of the gas are usually moving in constant random motion and they exert no force on each other.
Also, the temperature varies directly proportional to the average kinetic energy of the gas particles. As a result, when the kinetic energy of the particles increases, the temperature will also increase.
Learn more about the kinetic theory of gas here:
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HELP I BEG
What are two ways the atmosphere helps protect living things?
A. It traps enough energy from the Sun to keep Earth warm.
I B. It keeps Earth cold enough that most of the water is frozen and
can't evaporate.
O C. Most meteoroids bounce off its outer layers instead of striking
Earth's surface.
OD. It contains oxygen gas and carbon dioxide gas, which living things
need.
Answer:
I would say D and A
But i might be wrong
Answer:
A and D
Explanation:
Now try marking the other guy as brainiest.
PLEASE HELP ME ASAP
Use the equation to answer the question.
4NaCl + 2502 +_____
H2O +______02 →______Na2SO4 + 4HCI
Which numbers balance this equation?
(1 point)
O 2, 1, 2
O 1,2,4
O 2, 1,4
o 1,2,2
Answer: O 2, 1,4
Explanation:
A student performs a titration of 51.0 mL of a phosphoric
acid (H PO) solution of unknown concentration with a
standardized 1.25 M NaOH solution. The titration requires
26.2 mL of base to reach the third equivalence point. What is
the concentration of the H3PO4
solution?
From the information available in the question, the concentration of the acid is 0.21 M.
H3PO4(aq) + 3NaOH(aq) -----> Na3PO4(aq) + 3H2O(l)
Volume of acid(VA) = 51.0 mL
Concentration of acid (CA) = ?
Volume of base (VB) = 26.2 mL
Concentration of base (CB) = 1.25 M
Number of moles of acid (NA) = 1
Number of moles of base (NB) = 3
Using the formula;
CAVA/CBVB = NA/NB
CAVANB = CBVBNA
CA = CBVBNA/VANB
CA = 1.25 M × 26.2 mL × 1/51.0 mL × 3
CA = 0.21 M
The concentration of the acid is 0.21 M.
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lons form because the loss of one or more electrons makes
them less stable than their corresponding atoms; this state
requires more energy to maintain.
TRUE
FALSE
This statement lons form because the loss of one or more electrons makes them less stable than their corresponding atoms; this state requires more energy to maintain is FALSE.
An ion forms when an atom loses or gains one more electrons. This loss or gain of electrons causes the ion to gain the stable octet configuration. This stable octet configuration requires less energy to maintain than the corresponding atom.So, since the stable octet configuration of the ion requires less energy than the corresponding atom, the statement is false.
So, the statement lons form because the loss of one or more electrons makes them less stable than their corresponding atoms; this state requires more energy to maintain is FALSE.
Learn more about ions here:
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If the pressure of 50.0 mL of oxygen gas at 100°C increases from 735 mm Hg to 925 mm Hg, what is
the final volume? Assume temperature remains constant.
Answer: .039L
Explanation:
In chemical reactions, _______ always involves the release of energy during the reaction process.
a) the breaking of bonds
b) the formation of bonds
c) the addition of a catalyst
d) overcoming activation energy
Answer:
a. the breaking of bonds
Answer:
B
Explanation:
Hey, I am almost positive that the answer to this question is B. The breaking of bonds uses the energy but when they are created it releases energy. I hope this helps, Have a good day!
Part C
Describe the shape of the graph showed in part B.
(Is it like- a normal shape??)
This graph shows a straight line.
Answer:
The graph is a straight line that angles upward.
radium-223 decays with a half-life of 11.4 days, how long will it take for a 0.240-mol sample of radiuim to decay to 1.88 x 10-3 mol
The time taken for 0.240 mole sample of radiuim to decay to 1.88×10¯³ mole is 79.8 days
We'll begin by calculating the number of half-lives that has elapsed.
Original amount (N₀) = 0.240 mole
Amount remaining (N) = 1.88×10¯³ mole
Number of half-lives (n) =?N = 1/2ⁿ × N₀
1.88×10¯³ = 1/2ⁿ × 0.240
Cross multiply
1.88×10¯³ × 2ⁿ = 0.240
Divide both side by 1.88×10¯³
2ⁿ = 0.240 / 1.88×10¯³
2ⁿ = 128
2ⁿ = 2⁷
n = 7Thus, 7 half-lives has elapsed
Finally, we shall determine the time.Number of half-lives (n) = 7
Half-life (t½) = 11.4 days
Time (t) =?t = n × t½
t = 7 × 11.4
t = 79.8 daysTherefore, the time taken for 0.240 mole sample of radiuim to decay to 1.88×10¯³ mole is 79.8 days
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chlorine has two isotopes chlorine-35 and chlorine-37 with average atomic mass 35.5.find the percentage abundance of each isotopes
Answer:
75% Cl-35 and 25% Cl-37
Explanation:
chlorine has two isotopes chlorine-35 and chlorine-37 with average atomic mass 35.5.find the percentage abundance of each isotopes
assume Cl-35 has Y% Then Cl-37 has (100-Y) %
The weighted average of 35.5 is given by
[(35 x Y) + ((100-Y) x 37)]/100 = 35.5
so
(35 x Y) + ((100-Y) x 37) =3550
35Y + 3700 -37Y = 3550
-2Y = -15075% Cl-35 and 25% Cl-37
Y = so average weight chlorine is
75% Cl-35 and 25% Cl-37
The elements chlorine and iodine have similar chemical properties
because they
Answer:
They are both halogens and have the same number of electrons on their outer shell.
Any element with 7 electrons in the outermost shell will have similar properties. Thus other elements in the same column of the periodic table as chlorine will have similar properties.
If you liked my answer, please mark me brainliest!!!
The table below shows the dimensions of two colored cubes.
Dimensions of Cubes
Cube Side (cm) Mass
(g)
Yellow 3 135
Black 2 48
Answer: The correct answer is black because the product of its side and mass is lower.
Explanation: The density of a substance is defined as the amount of matter that can be stored in a given volume.
Hence, the black cube will be denser because the product of its side and mass is lower.
Answer: it was wrong on my test
Explanation:
literally dont believe them
CALCULATE the no of atoms in 0.6g of Ca ?
Explanation:
CALCULATE the no of atoms in 0.6g of Ca ?
Answer:
Explanation:
Every periodic table is rounded differently. My numbers will be approximate.
mols = 0.6 grams/ 40 grams / mol 40 is the number you need to get from the periodic table.
mols = 0.015
1 mol of anything is 6.02 * 10^23
So the formula you should use is atoms = 0.015 * 6.02 * 10^23
Answer: 9.03 * 10^21
To what pH should you adjust a standard hydrogen electrode to get an electrode potential of -0.128 V ? (Assume that the partial pressure of hydrogen gas remains at 1 atm.) Express your answer using two decimal places.\
The pH of the standard hydrogen electrode that has electrode potential of -0.128 V is 4.3.
The equation of the hydrogen electrode is;
2H^+(aq) + 2e ⇄ H2(g)
The standard electrode potential of hydrogen is 0.00 V
Using the Nernst equation;
Ecell = E°cell - 0.0592/n log Q
Now;
E°cell = 0.00 V
n = 2
Q = 1/[H^+]
-0.128 = 0.00 - 0.0592/2 log 1/[H^+]
-0.128 = 0.00 - 0.0296 log 1/[H^+]
-0.128 = - 0.0296 log 1/[H^+]
-0.128/ - 0.0296 = log 1/[H^+]
1/[H^+] = Antilog (4.32)
[H^+] = 4.79 × 10^-5
Now;
pH = -log[H^+]
pH = -log (4.79 × 10^-5)
pH = 4.3
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Grace wanted to find out the best conditions for growing lettuce plants.
She took 4 trays and planted 8 lettuce plants in each.
The results of her investigation are shown below.
How many days did the investigation last?
Use the table to help you.
Explanation:
the investigation lasts for 7 days !
hope this helps you.
A solution that contains less than the amount of solute that would be dissolved at equilibrium is considered to be
Answer:
dilute solution
A solution containing less solute than the equilibrium amount is called a dilute solution. The solvent has a limited capacity to dissolve a solute.
Explanation:
Why we use two different methods for detection of cogulase enzyme ? Or what other reason or what basic different between them?
A radioactive sample has a half life of 1 hour. If you start with 1.000 gram of it at noon, how much of it remains at 4pm
The amount of the sample remaining at 4pm is 0.0625 g
We'll begin by calculating the number of half-lives that has elapsed
Half-life (t½) = 1 hour
Time (t) = 4 hour
Number of half-lives (n) =?n = t / t½
n = 4 / 1
n = 4Finally, we shall determine the amount the sample remaining at 4pmNumber of half-lives (n) = 4
Initial amount (N₀) = 1 g
Amount remaining (N) =?[tex]N = \frac{N_0}{ {2}^{n}} \\ \\ N = \frac{1}{ {2}^{4}} \\ \\ N = \frac{1}{16} \\ \\ N = 0.0625 \: g[/tex]
Thus, the amount remaining at 4pm is 0.0625 g
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What is caused by temperature differences in the mantle resulting in plate movement?
Crust
Convection Currents
Lithosphere
Answer:
Convection Currents
Explanation:
TRUE or FALSE 1. Badminton began in India as a game called poona. 2. The shuttle was then called a bird because it was made from goose feather. 3. Ti jian zi played by throwing up in the air. 4. Racket is made of either metal or synthetic materials. 5. Head, throat, shaft, and handle are the parts of the rackets. 6. Shuttlecock is made up of 16 goose feathers. 7. Forehand, Backhand, and Sidestroke are the three basic skills of Badminton. 8. Backhand is use to depends on the type of shot to be executed. 9. Stroke means to propel with a controlled swinging blow. 10. The whole size of the badminton court has 39 meters.
Answer:
1.false
2.true
3.true
4.true
5.false
6.false
7.false
8.true
9.false
10.true
Explanation:
I took the test
