Answer:
t(half-life) = 1600 yrs
Explanation:
All radio decay follows 1st order kinetics and therefore can be applied to the expression A = A₀e^(-kt)
A = current activity
A₀ = initial activity
k = decay constant
t = time of decay
Half-Life = 0.693/k
k = ln(A/A₀) / -t = ln(0.25) / -3200yrs = 4.33x 10⁻⁴ yrs⁻¹
Half-Life => t(1/2) = (0.693/4.33 x 10⁻⁴)yrs⁻¹ = 1600 yrs.
As an electron in an atom moves from a higher energy state to a lower energy state, the atom
1 becomes a negative ion
2 becomes a positive ion
3 releases energy
4 absorbs energy
Answer:
3 releases energy
Explanation:
An electron in an energy level has a definite amount of energy associated with it at that level.
Electrons can undergo transitions from one level to another. However, when the electron changes its state, it must absorb or emit the exact amount of energy which will bring it from the initial to the final state.
When the electron is excited, it moves from the ground state to an excited state, it must absorb energy. On returning from an excited state to a lower level or the ground state, energy is emitted, giving rise to a line in the spectrum.
Answer: 3 because it releases energy
_____are chains of amino acids
lipids
carbs
proteins
nucleic acids
Answer: proteins
Explanation:
difference between NaOH and HCI
Answer:
hcl:-is as strong acid than water.naoh:-is as strong base than Nh3
Explanation:
hence naoh is base and HCl is acid
60 points one of the questions im stuck on
Answer:
6 m/s is the answer.
Explanation:
speed = distance/time
(please mark me brainliest if you can)
Answer:
6 meters per second
Explanation:
they fly 60 meters in 10 seconds. So to find how many meters they fly in one second, we divide by 10.
60m/10secs = 6 m/s
What products are always made when any carbon-based fuel
is burned in the presence of oxygen?
a) carbon dioxide and hydrogen
b) carbon dioxide and water
c) oxygen and carbon dioxide
d) oxygen and water
Answer:
B) carbon dioxide and water
Answer: B.) carbon dioxide and water
Explanation:
bc I got it right?
A gas occupies 2.5 L at 2.5 atm. What is the volume if the pressure changes to 1.5 atm?
Answer:
p1v1=p2v2
2.5×2.5=1.5×v2
6.25=1.5v2
6.25 /1.5=v2
4.16L=v2
Which of the following might be included in a chemical
reaction?
a) Molecules
b) lons
c) Pure elements
d) All of the above
Answer:
I think it's D
Explanation:
In the expression 3H20, the 3 is a ____, while the 2 is a _____. A) coefficient: superscript B) coefficient: subscript C) superscript: subscript D) superscript: coefficient
Answer:
B) coefficient: subscript
Explanation:
Given
[tex]3H_2O[/tex]
Required
What does 3 and 2 represents
On a general term:
In [tex]nA_m[/tex]
[tex]n = The\ coefficient\ of\ A[/tex]
And
[tex]m = The\ subscript\ of\ A[/tex]
So, by comparing [tex]3H_2O[/tex] with the general term, [tex]nA_m[/tex]
[tex]n = 3[/tex]
[tex]m = 2[/tex]
Hence,
3 = coefficient and 2 = subscript
The correct answer is A) coefficient: superscript.
Given molecule:-
[tex]3H_2O[/tex]
In general:
[tex]2B_3[/tex]
2 is the coefficient of B, and 3 is the subscript of B.
So, by comparing with the given molecule, [tex]3H_2O[/tex]
3 = coefficient and 2 = subscript
Hence , the correct option is A.
To know more about:-
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A sample of unknown element X contains the following isotopes: 80% of C -64, 15% of X - 65, and 5% of X-66. What is the average atomic mass of element X? Can somebody help me with this question. Will mark brainliest.
Answer:
64.25
Explanation:
Average atomic mass = percentage × mass of all isotopes/ 100
Relative atomic mass = 80*64+15*65+5*66/100
=5120+975+330/100
=6425/100
64.25
why does the moon appear to be so bright in the sky
Answer:
The shine of the Sun on the lunar surface brightens it, while also giving the moon "dark sides". Its position in Earth orbit allows it to have certain phases because of its orbital position relative to the sun. You're welcome.
Explanation:
During the formation of the compound sodium chloride, the correct symbol and charge for each of the ions must be...
O Na+1 and Cl-1
O Na+1 and F-1
O Na+1 and Br-1
O Na+1 and O-2
Answer : The correct symbol and charge for each of the ions must be [tex]Na^{+1}[/tex] and [tex]Cl^{-1}[/tex].
Explanation :
Covalent compound : It is defined as the compound which is formed by the sharing of electrons between the atoms forming a compound.The covalent compound are usually formed when two non-metals react.
Ionic compound : It is defined as the compound which is formed when electron gets transferred from one atom to another atom.Ionic compound are usually formed when a metal reacts with a non-metal.
As we know that the sodium chloride is an ionic compound in which sodium is an alkali metal and has one valence electron and chlorine is a non-metal and has 7 valence electrons.
When sodium atom donates an electron to a chlorine atom then it forms an ionic compound that is sodium chloride (NaCl) and the resulting positive ion [tex]Na^{+1}[/tex] and negative ion [tex]Cl^{-1}[/tex] form a stable ionic compound.
Hence, the correct symbol and charge for each of the ions must be [tex]Na^{+1}[/tex] and [tex]Cl^{-1}[/tex].
How many molecules are in 200.0 g of ammonium sulfide
Answer: 1.51355 mol.
Explanation:
Benjamina started her walk from the front door of her ground floor apartment.She walked 6 meters to the corner of the building and then turned the corner and walked 10 meters to her friends apartment.Identify the difference between the distance she walked and her displacement.
Answer:
See explanation
Explanation:
The major difference between distance and displacement is that distance is a scalar quantity while displacement is a vector quantity. Scalar quantities have magnitude without direction while vector quantities have both magnitude and direction.
The distance covered by Benjamina in both cases just refer to the difference in her position at each time without reference to the direction in which she changed her position.
Her displacement will clearly mention the direction in which she moved both when she walked to the front door of her apartment and when she walked to a friend's apartment.
Which term describes this reaction?
addition
condensation
elimination
substitution
Addition is the answer
What is the theoretical yield, in grams, and the percent yield of a reaction of 3.0 moles of two hydrogen atoms and 2.0 moles of Iodine atoms to produce one mole of Hydrogen Iodine.
Answer:
512g, 25%
Explanation:
H_2+I_2→ 2HI
3 moles H_2× 2moles HI/1 mole of H_2= 6 moles of HI
2moles I_2×2 moles of HI/1 mole of I_2= 4 moles of HI
Now, theoretical yield of HI = 4 moles ×128 g/ mole = 512 g
percentage yield = (128g/512g)×100 = 25%
Humans are most abundant during which geological era?
Cenozoic
Precambrian
Palcozoic
Mesozoic
Answer:
Cenoizic
Precamborian
A 500g sample of Ca-37 decays for 910ms. How much of the original sample remains?
Answer:
15.6 g
Explanation:
Given that;
Mass of original sample = No = 500g
mass of sample remaining at 910 ms = N = ?
time taken to decay= 910 ms
Half life of Ca-37 = 181 milliseconds
From;
N/No = (1/2)^t/t1/2
N/500 = (1/2)^910/181
N/500 = (1/2)^5
N/500 = 1/32
32 N = 500
N = 500/32
N = 15.6 g
Which of the following would be an example of applied science?
Investigating how carbon dioxide levels impact ocean pH
Investigating why water expands when it freezes
Investigating the conductivity of metalloids
Investigating how to develop a more efficient solar panel
Answer:
Investigating how carbon dioxide levels impact ocean pH
Explanation:
I hope this helps! :)
What is an atomic number ?
Explanation:
the number of protons in the nucleus of an atom, which is characteristic of a chemical element and determines its place in the periodic table
Spring and autumn both have a certain day where the amount of daytime hours
and nighttime hours are the same. What is this day called?
a. Equator
b. Equilibrium
c. Equality
d. Equinox
Answer:
d. Equinox
Explanation:
A certain day in spring and autumn where the amount of daytime hours and nighttime hours are the same is called equinox.
Equinox occurs twice in a year on March 20 and September 23rd.
During an equinox, the south and north hemisphere of the earth are receiving equal amount of sunlight. The opposite of equinox is solstice in which the duration of light is unequal. The equator is the only great circle that is a line of latitude.Using the reaction below determine the amount of Sulfur proceduced in grams (this is a limiting reaction question) 2 H2S + SO2 -> 3 S + H2O 3.26g of dihydrogen sulfide react with 4.42 g of sulfur dioxide
Answer:
= 2.2 g pf S. produced
Explanation:
Balanced Reaction equation:
[tex]2H_{2} S + SO_{2}[/tex] → [tex]3S + 2H_{2} O[/tex]
1 mole of H2S - 34.1g
? moles - 3.2g
= 3.2/34.1 = 0.09 moles of H2S
Also,
1 mole of S02 - 64.07 g
? moles - 4.42g
= 4.42/64.07 = 0.069 moles of SO2
Meaning SO2 is the limiting reagent
Finally, 3 moles of S - 32g of sulphur
0.069 mole = ? g of Sulphur
= 0.069 x 32
= 2.2 g pf S.
what is the relative formula mass of butane?
Answer:
The molecular formula of butane is C4H10. Calculate its molar mass.58.1 g/mole 14. is answer.
Explanation:
I hope it's helpful!
The group of the periodic table determines the ___.
Answer: C. Number of valence electrons
Explanation: A group is a vertical column in the periodic table, which signifies the number of valence shell electrons in an element's atom. Example: all the elements in group 1 have 1 electron in their outer most shell.
what is the first thought when u hear the word mole?
The word mole is one of those crazy words that have multiple meanings that can sometimes lead to confusion. Perhaps your first thought after hearing the word is a cute little animal that burrows in the ground.
pls mark me as brainliest and thank me
Liquids are not easily compressible but flow easily.
O True
O False
A solution has a pOH of 12. Which best describes the solution?
Answer:
The solution is acidic.
Explanation:
The nature of solution will be acidic.
What is solution?A solution is just a uniformly dispersed mixture of more than solutes in a solvent.
What is acidic?In nature, chemical species with a pH value between. are termed acidic. Acidic substances have a sour flavor in general. In the beginning, acid was defined as a sour substance that interacts with metal as well as turns blue litmus red.
Calculation of pH.
Given data:
pOH = 12
The nature of the solution can be calculated by pH formula.
pH+ pOH = 14
Put the value of pOH in above expression.
pH = 14-pOH
pH = 14-12
pH = 2.
Hence, the nature of the solution will be acidic.
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What is an advantage of using natural gas rather than a coal burning power plant?
Answer:
I hope it helps u
Explanation:
The advantages of using natural gas rather than coal are the following,
Natural gas is present in large amount than coal.Natural gas is less costly than other fossil fuel sources of energy. It increases security by decreasing dependence.Natural gas is more environmentally friendly.Natural gas is much safer to store.It is reliable.Natural gas is a fossil fuel, though the global warming emissions from its combustion are much lower than those from coal or oil.Natural gas emits 50 to 60 percent less carbon dioxide (CO2) when combusted in a new, efficient natural gas-power plant compared with emissions from a typical new coal plant.If an atom of calcium has two dots for its Lewis structure, then it means that this atom has...
O 18 electrons
O 2 valence electrons in shell 4
O 2 valence electrons in shell 1
O three shells, only
Answer:
2 valence electrons in shell 4 is ur ans
What happens in all solutions?A. Two gases are in the same space.
B. Liquids are stirred together rapidly.
C. A solid mixes with a liquid and slowly settles out.
D. Two substances mix evenly without reacting.
Answer:
D. Two substances mix evenly without reacting.
Explanation:
Solutions are homogenous mixtures of solutes and solvents.
In a solution, the solute particles are distributed uniformly in the solvent. The solute is the substance that is dissolved to make the solution. It is usually present in smaller amount than the solventThe solvent is the dispersing substance that allows the solute to go into solution. The solute could be solid or liquid or gasThe solvent could be solid or liquid or gas but most times liquid.Short description about health science
Answer:
Both traditional Western and alternative medicine can be considered health sciences. ... The field includes the study of medicine, nutrition and other health-related issues and the affect they may have on both humans and animals.
Explanation: