What % of original U238 remains after three half lives?
1-50
2-25
3-12.5
4-6.25
Answer:
12.5
Explanation:
After three half-lives, one eighth (1/2 x 1/2 x 1/2) of the uranium-238 will remain. One-eighth equals 12.5%
The concentration of a benzene solution prepared by mixing 12.0 g
C6H6 with 38.0 g CCl4 is __________ molal
Answer: The concentration of a benzene solution is 4.05 molal
Explanation:
Molality of a solution is defined as the number of moles of solute dissolved per kg of the solvent.
[tex]Molality=\frac{n\times 1000}{W_s}[/tex]
where,
n = moles of solute
[tex]W_s[/tex] = weight of solvent in g
moles of [tex]C_6H_6[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{12.0g}{78g/mol}=0.154mol[/tex]
Now put all the given values in the formula of molality, we get
[tex]molality=\frac{0.154\times 1000}{38.0g}=4.05[/tex]
Therefore, the concentration of a benzene solution is 4.05 molal
An aqueous solution contains
32.7% KCI (weight weight %)
How many grams of KCl are
contained in 100 g of this solution
Molar Mass
KCE: 74.55 g/mol
H20 18.016 g/mol
Answer:
32.7
Explanation:
I just did it and got it right
what energy is walking?
A. light energy
B. sound energy
C. Thermal energy
D. Mechanical energy
E. electrical energy
Answer:
Mechanical
Explanation:
Whoever gets it right gets brainliest!!
When different atoms join together, they are called a compound. Compounds are made of molecules (so molecules could be an alternate answer, but not all molecules are compounds)
Answer:
it is compound
Explanation:
Two or more elements combined into one substance through a chemical reaction, such as water, form a chemical compound. All compounds are substances, but not all substances are compounds.
Hydrogen has an oxidation number of +1 in all compounds excepts when it binds with metals and has an oxidation state of -1.
Answer:
See explanation
Explanation:
In the periodic table, hydrogen is placed in group 1 for convenience. Hydrogen is not a metal, however, its common oxidation state is +1. It easily forms a univalent positive ion just like group 1 elements.
So, when hydrogen is combined with strongly electropositive metals such as sodium, lithium, etc, hydrogen accepts one electron and exhibits an oxidation state of -1 in those compounds.
Such compounds in which hydrogen is combined with strongly electropositive metals to give a binary compound is called a hydride.
Where are new volcanoes in the Hawaiian island chain forming
Answer:
The Hawaiian Islands are a very small section of a huge chain of volcanic islands that crosses the northern half of the Pacific Ocean, called the Hawaiian-Emperor Volcanic Island Chain, which is over 6,000 kilometres long. The chain is linear, with a large bend in the middle: the southern half is called the Hawaiian Ridge and the northern half is called the Imperial Seamount.
Explanation:
Green plants use light from the Sun to drive photosynthesis, a chemical reaction in which liquid water and carbon dioxide gas form aqueous glucose C6H12O6 and oxygen O2 gas. Calculate the moles of oxygen produced by the reaction of 0.800mol of carbon dioxide. Be sure your answer has a unit symbol, if necessary, and round it to 3 significant digits.
Answer:
0.800 mol of O2
Explanation:
Calculate the moles of oxygen produced by the reaction of 0.800mol of carbon dioxide.
The balanced equation for the reaction is given as;
6CO2 + 6H2O → C6H12O6 + 6O2
From the reaction;
6 mol of CO2 produces 6 mol of O2
0.0800 mol of CO2 would produce x mol of O2
6 = 6
0.0800 = x
Solving for x;
x = 6 * 0.800 / 6
x = 0.800 mol
A group of students is setting up a test to see whether earthworms, like those shown in the photo, prefer rough or smooth surfaces
Answer:
they like smooth
Explanation:
Definition: This is a net gain or loss of electrons.
Example: Your hair gains one when you pull a wool sweater over your head.
res)
Term:
Answer:
Elecric charge/ Electricity
Explanation:
Electric charge is the net gain or loss of electrons
I hope im right!!
NEEED HELP NOW
A new drug has been released to the public and is popular among
consumers. It is effective in relieving high blood pressure. However, it has
altered some patients' personalities. Which stage of the engineering process
may address this negative side effect?
A. Evaluating test results
B. Looking for improvements
C. Screening
D. Testing
Answer: looking for improvements
Explanation:
Answer:
B. Looking for improvements
Explanation:
took the quiz and got in right on a pex
How many moles are in 2.5L of 1.75 M Na2CO3
Answer:
4.375 moles Na2CO3
Explanation:
Formula for molarity is;
M = n/V
Where;
M is molarity
n is number of moles
V is volume
Making n the subject we have;
n = VM
We are given;
M = 1.75 M
V = 2.5 L
Thus;
n = 2.5 × 1.75
n = 4.375 moles Na2CO3
Answer:
4.375 moles Na2CO3
Explanation:
Have a great day
A chemist needs to know the mass of a sample of to significant digits. He puts the sample on a digital scale. This is what the scale shows:
0
0
0
7
6
.
3
g
If this measurement is precise enough for the chemist, round it to significant digits.
Otherwise, press the "No solution" button.
How many molecules are in 13.2 L F2
Answer:
3.55 x 10^23 molecules F2
Explanation:
molecules = moles x avogadro number
1 mole of gas occupies 22.4 L
moles of F2 = 13.2/22.4= 0.589 moles
moles F2 = 0.589 x 6.022 x 10^23 = 3.55 x 10^23 molecules F2
Which best describes the process that occurs when liquid water becomes
ice?
Answer:
Freezing
Explanation:
When a liquid goes to a solid, this process is called freezing.
Answer:
The water molecules get condensed and form a solid matter called ice. This process is called Condensation.
The smallest arteries in your body are called _____. arterioles capillaries veins bronchioles
Answer: arterioles
Explanation:
HELPPP HURRY FIRST GET BRAINLEST The rusting of steel wool occurs when the iron in the steel wool combines with what substance?
carbon dioxide
hydrogen
nitrogen
oxygen
Answer:
iron oxide. aka. oxygen
Explanation:
Rust is the result of a chemical reaction between iron and oxygen, otherwise known as iron oxide. Since steel wool -- and steel in general -- is largely made of iron, steel wool is prone to rust if it doesn't have a rustproof coating on it. The actual reaction that creates rust happens when two iron atoms mix with three oxygen atoms in water; the oxygen bonds to the metal, and a new compound is formed.
Question 2 (1 point)
Which of the following does NOT involve a chemical reaction?
Fallen leaves decay in a compost pile.
Leaves change color in the fall.
O A fire burns a pile of fallen leaves.
A pond freezes over in the winter.
Answer:
D. A pond freezing over is not a chemical reaction, it is a physical reaction.
Laura can use a toy car to demonstrate the force of gravity by doing which of these?
Letting the toy car roll down a ramp
Placing the toy car on the floor
Lifting the toy car onto a shelf
Pushing the toy car across a table
Answer:
letting the car fall down the ramp i got that right.
Explanation:
If I have 2.500 grams of magnesium how many moles of magnesium do I have?
Answer:
0.1029(rounded to sig figs)
Explanation:
convert from grams to moles
Amount in grams/molar mass of substance
Molar mass of Mg=24.305
So, 2.500/24.305=0.1028594939
Rounded to 0.1029
Which part of a calcium atom in the ground state is represented by the dots in its Lewis electron-dot diagram?
Answer:
There are two dots are present on the left side of calcium atom which represents the unpaired electrons present in the outermost shell. This structure is presented by Lewis in order to show the number of unpaired electrons in the atom.
Explanation:
If 4 moles of sulfur reacts with 9.5 moles of oxygen, how many moles of oxygen would remain after the reaction ?
3 Zn + 2 MnF3 ---------> 2 Mn + 3 ZnF2
Using the reaction above, calculate how many grams of manganese (Mn) are produced in this reaction when 8.5 moles of Zinc (Zn) are used as a reactant?
Answer:I’ll ask my teacher
Explanation:
Which statement best describes the energy in the food web? A. The amount of energy available at level B depends on the amount of energy available at level C. B. The amount of energy available at level A depends on the energy provided from an abiotic source. C. The amount of energy available at level C is greater that the amount of energy available ate level A. D. The amount of energy available at level B is transferred to level A
Answer:
The amount of energy available at level A depend on energy provided from an a biotic source
help please will give brainly if right
Answer:
B and D
Explanation:
Because its adaptions they need to survive in the cold.
We obviously cannot wait for million years to determine the half-life of technetium, or even years to determine the half-life of plutonium. The half-life of a substance is determined using a Geiger counter, which is essentially a tube filled with an inert gas. When a particle decays and produces radiation, it briefly ionizes the gas and produces a detectable electric pulse, which is amplified and counted by a detector (before digital displays were available, you would hear clicks and see a needle register on a dial). Determine the formula for the half-life of a substance with an initial count of pulses and a count of pulses minutes later.
The question is incomplete, the complete question is;
We obviously cannot wait for 4 million years to determine the half-life of technetium, or even 87.7 years to determine the half-life of plutonium. The half-life of a substance is determined using a Geiger counter, which is essentially a tube filled with an inert gas. When a particle decays and produces radiation, it briefly ionizes the gas and produces a detectable electric pulse, which is amplified and counted by a detector (before digital displays were available, you would hear clicks and see a needle register on a dial). Determine the formula for the half-life of a substance with an initial count of No pulses and a count of N1 pulses M minutes later.
Answer:
M1/2 = 0.693/k
Explanation:
Given that the initial count rate is No pulses
The count rate after M minutes is N1
Then from;
A = Aoe^-kt
A= N1
Ao=No
I can now write;
N1 = Noe^-kM
The half life is the time taken for the activity of the radioactive nuclide to reach half its initial value. Hence;
N1/No =e^-kM = 1/2
Taking natural logarithm of both sides as shown below;
-kM1/2 = ln(1/2)
M1/2 = - (ln(1/2)/k)
M1/2 = 0.693/k
HELP I WILL GIVE YOU BRAINLIST!!!
Pick one substance (ex: water and table salt) and compare two of the atoms connected to each other (ex: H and O, Na and Cl) and answer the following questions for each pair:
1)Are they close or far away from each other on the periodic table?
Do they have similar atomic radii?
2)Do they have a large or small difference in ionization energy? What about for electron affinity?
help please i need this
what is the percentage composition of carbon and hydrogen in ethane(c2h6,molecular mass 30.0)
Answer
% of C in C2H6= (2×12)/30×100=80%
% of H in C2H6= (3×2)/30×100=20%
Explanation:
2C+3H2-C2H6
nC=12, nH=1, nC2H6=30
2moles of C-1mole of C2H6
3moles of H-1 mole of C2H6
% of C in C2H6= (2×12)/30×100=80%
% of H in C2H6= (3×2)/30×100=20%
what grade percentage is developing, proficient, exceeding, and emerging?
Answer:
Grade A is the best percentage that is developing, proficient, exceeding, and emerging