Iodine – 125 emits gamma rays when it decays to Tellerium-125 and has a half-life of 60 days. If a 0.020 g pellet of iodine – 125 is implanted into a prostate gland, how much iodine – 125 remains there after one year
Answer:
0.0003125 g
Explanation:
Given data:
Half life of iodine-125 = 60 days
Mass of iodine pellet = 0.020 g
Mass of iodine remain after one year = ?
Solution:
one year = 365 days
Number of half lives = Time elapsed/ half life
Number of half lives = 365 days/ 60 days
Number of half lives = 6
At time zero = 0.020 g
At 1st half life = 0.020 g/2 = 0.01 g
At 2nd half life = 0.01 g / 2 = 0.005 g
At 3rd half life = 0.005 g/2 = 0.0025 g
At 4th half life = 0.0025 g / 2 = 0.00125 g
At 5tht half life = 0.00125 g / 2 = 0.000625 g
At 6th half life = 0.000625 g/ 2 = 0.0003125 g
The Jones family is expecting guests at any moment they spray room freshener in one corner of the kitchen to remove the strong foods smell The room spray quickly becomes evenly distributed throughout the room making the whole kitchen smell fresh what is happening in this system?
Answer: Entropy is increasing
Explanation:
Which reaction product (A or B) is more likely to form in the epoxide ring opening reaction? Consider resonance structures.
Answer:
Reaction product A is more likely to form in the epoxide ring-opening reaction
Explanation:
The diagram for the reaction can be seen in the image attached below.
An epoxide is any class of organic compound, cyclic ethers, having a three-membered ring; they are usually prepared by selective oxidation of alkenes or by ring-closure of halohydrins(any class of organic compound having a hydroxyl functional group and a halogen on neighboring carbon atom ) which are used in making plastic.
How do you know that K, an alkali metal is very reactive?
a. It conducts heat
b. It conducts electricity
C. It is a soft and shiny metal
d. It contains one valence electron
Answer:
d. It contains one valence electron.
Since, potassium has one valence electron so it can easily donate one electron during chemical reaction.
The chemical formula for a molecule that contains two chlorine (Cl) atoms is
Chlorine is a halogen gas element which has atomic number 17 which is in group 17, p block and period 3
The electron configuration of Cl : [Ne] 3s² 3p⁵ ⇒ 2, 8, 7
So the valence electron is 7, so to achieve stability you will need 1 more electron so it is stable like Argon
Cl will be covalently bonded (using shared electron pairs) with other Cl atoms to form a non-polar molecule, namely Cl₂
A gas was trapped in a container containing 10mL of air at a pressure of 1.0 atm. What will be the new volume,if the pressure is changed to 5 atm at the same temperature?
Answer:
The answer is 2 mLExplanation:
The volume of the gas can be found by using the formula for Boyle's law
[tex]P_1V_1 = P_2V_2[/tex]
where
P1 is the initial pressure
P2 is the final pressure
V1 is the initial volume
V2 is the final volume
Since we are finding the new volume
[tex]V_2 = \frac{P_1V_1}{P_2} \\[/tex]
We have
[tex]V_2 = \frac{10 \times 1}{5} = \frac{10}{5} \\ [/tex]
We have the final answer as
2 mLHope this helps you
Explain how cells are the basic unit of all living things
Answer:A cell is the smallest unit of a living thing. A living thing, whether made of one cell (like bacteria) or many cells (like a human), is called an organism. Thus, cells are the basic building blocks of all organisms. ... Several systems that function together form an organism (like a human being).
Hope this helped! If it did leave a brainliest.
Have an amazing night/day!
Where are metals found on the periodic table?
O Metals are on the far left side of the periodic table
Metals are found on the left side/middle
O Metals are on the bottom two rows of the periodic table
Metals are found on the stairstep line
A gas occupies 1.00 L at 273 K. What is the volume at 606 °C?
Answer:
3.22 L
Explanation:
0.00 C = 273 K
k = C +273
606 K + 273 K = 879 K
879/273 = 3.219
V2 = 3.22 L
how the charge of an element is used to determine the chemical formula if the elements have equal and unequal charges.
Answer:
The charges are typically used to determine the mole ratio and composition of the individual atoms of elements in the compound
Explanation:
Take for instance the following compounds:
[tex]NaOH[/tex] and [tex]H_{2} O[/tex]
Na has a charge of +1 and OH -1. equal charge means equal composition.H has charge of +1 while O has charge of -2. The charges are unequal, so the mole ratio for conversion would require multiplication by 2...which makes H two atoms but oxygen one atom in the compound.I hope this helps.
In the diagram below, particles of the substance are moving from the liquid phase to the gas phi
they move from the gas phase to the liquid phase.
The gas and liquid are at
O equilibrium
a high vapor pressure.
a low vapor pressure.
zero vapor pressure.
Answer:
Equilibrium
Explanation:
Correct on edge 2020
Answer:
A - Equilibrium
Explanation:
For edge:)
4.60 g of 3-hexanol were obtained from 5.33 g of hex-3-ene. Determine the percentage yield of 3-hexanol. a Determine the moles of hex-3-ene, , used in the experiment. (To avoid introducing rounding errors on intermediate calculations, enter your answer to four significant figures.)
Answer:
Explanation:
C₆H₁₂ + H₂O = C₆H₁₃OH
hexene hexanol
1 mole 1 mole
Mol weight of hexene = 84
Mol weight of hexanol = 102
5.33g of hexene = .06345 moles
4.6 g of hexenol = .0451 moles
percentage yield of hexanol
= .0451 x 100 / .06345
= 71.07 %
Moles of hexene used = .0451 moles
An iron ore sample contains plus other impurities. A 896-g sample of impure iron ore is heated with excess carbon, producing 182 g of pure iron by the following reaction: What is the mass percent of FeO2 in the impure iron ore sample
Answer:
20.3%
Explanation:
Given mass of impure ore = 896g and mass of pure iron to be 182g after purification,
[tex]\frac{(896-182)g}{896}[/tex] × 100
= 79.7%
in subtracting the weight of impure mass from that of the pure sample, we are left with the mass of the impurities alone.
This means the mass percent of pure iron in this iron ore sample is 20.3%.
Let me know if this was helpful.
Specialist species can respond more easily to changing environmental conditions tan can generalist species OTrue O False
Answer:
false
Explanation:
what is listed on the right side of a chemical equation
Explanation:
The substances that "go in" to a chemical reaction are called the reactants (by convention these are usually listed on the left side of a chemical equation), and the substances found that "come out" of the reaction are known as the products (by convention these are usually found on the right side of a chemical equation
Answer: The reactants that go into the chemical reaction are on the left of the equation. The substances that come out of the chemical reaction are usually on the right side of the equation.
Hope it helps!
If 18.2 of 0.800 solution are needed to neutralize 5.00 of a household ammonia solution, what is the molar concentration of the ammonia
Answer:
2.91M is the concentration of the household ammonia solution
Explanation:
18.2mL of a 0.800M HCl solution to neutralize 5.00mL
The reaction of HCl with NH3 is:
HCl + NH3 → NH4Cl
Thus, the moles of HCl needed to neutralize the household are equal to moles of NH3. That is:
18.2mL = 0.0182L * (0.800mol / L) = 0.01456 moles HCl = Moles NH3.
In 5.00mL = 0.005L:
0.01456 moles NH3 / 0.005L =
2.91M is the concentration of the household ammonia solutionCalculate the mass of sodium acetate that must be added to 500.0 mL of 0.300 M acetic acid to form a pH
Answer:
22.4 g
Explanation:
Calculate the mass of sodium acetate that must be added to 500.0 mL of 0.300 M acetic acid to form a pH = 5.00 buffered solution.
Step 1: Given data
Volume of solution: 500.0 mL
[acetic acid]: 0.300 M
pH = 5.00
pKa of acetic acid: 4.74
Step 2: Calculate the concentration of sodium acetate
We will use the Henderson-Hasselbach equation.
pH = pKa + log [sodium acetate]/[acetic acid]
5.00 = 4.74 + log [sodium acetate]/0.300 M
[sodium acetate] = 0.546 M
Step 3: Calculate the moles of sodium acetate
We have 500.0 mL of a 0.546 M sodium acetate solution
0.5000 L × 0.546 mol/L = 0.273 mol
Step 4: Calculate the mass of sodium acetate
The molar mass of sodium acetate is 82.03 g/mol.
0.273 mol × 82.03 g/mol = 22.4 g
Imagine an element that has 15 protons, 16 neutrons, and 18 electrons. Which of the following would NOT be considered an isotope of this element? *
15 protons, 16 neutrons, and 15 electrons
15 protons, 17 neutrons, and 15 electrons
15 protons, 15 neutrons, and 18 electrons
Answer:
Explanation:
Option 1 15. Proton 16 neutron 15 electron
Isotopes have same atomic no but different atomic mass
Explain what is wrong with the following structure.
HH—0:
Answer:
for the Lewis diagram of water, hydrogens should go on the outside with oxygen in the center
Explanation:
hydrogens always go on the outside
What element does this model represent?
A
Potassium
B
Sodium
C
Oxygen
D
Boron
When temperature drops, particle speed decreases.
True?
False?
yes they decrease when the temperature drops so it's true
A chemist must prepare 650.0mL of sodium hydroxide solution with a pH of 13.90 at 25°C. He will do this in three steps:
Answer:
1. Weigh 3.27 ×10⁻⁴ ng of NaOH in a special balance for weighing in nanograms
2. Measure a volume of 650 mL in a test tube
3. Make the solution by mixture
Explanation:
NaOH is a strong base. As every strong base, can be completely dissociated:
NaOH → Na⁺ + OH⁻
If pH is 13.90, we can calculate the [OH⁻], so we would know the molarity of NaOH.
1 mol of NaOH can generate 1 mol of OH⁻
[OH⁻] = 10⁻¹³'⁹ = 1.26×10⁻¹⁴ M
In conclussion, molarity of NaOH is 1.26×10⁻¹⁴ M
M = moles of NaOH / volume of solution
We convert the volume from mL to L
650 mL . 1 L /1000mL = 0.650 L
Moles of NaOH = 0.650 L . 1.26×10⁻¹⁴ M = 8.18×10⁻¹⁵ moles
We convert the moles to mass, to determine the grams:
8.18×10⁻¹⁵ moles . 40 g/mol = 3.27 ×10⁻¹³ g
We can convert the grams to ng = 3.27 ×10⁻⁴ ng
What is another way scientists find planets being blocked by the light of a star?
PLEASE ANSWER!
Answer:
The Short Answer: All of the planets in ... Planets that orbit around other stars are called exoplanets. All of the ... So, astronomers use other ways to detect and study these distant planets.
What are most membranes made up of?
layers of ducts
layers of epithelial tissue
layers of bursae
Answer:
layers of epithelial tissue
Answer:
It's B
Explanation:
How many degrees along its orbit does the Moon travel between new moons?
Answer:
The moon orbits quite fast: it moves about 0.5 degrees per hour in the sky. In 24hrs it moves 13 degrees. the moons observed motion eastward results from its physical motion of the moon along its orbit around the earth
Plz mark brainliest
round 77.682517 to four figures
How many grams of F are in 365 g CaF2 ?
Answer:
177 grams
Explanation:
moles of CaF₂ = [tex]\frac{mass}{molar mass}[/tex] = [tex]\frac{365}{78}[/tex] = 4.67949
moles of F-atom = 2×moles of CaF₂ = 2×4.67949 = 9.35898
(mol)×(molar mass)= 9.35898×19 = 177.82062
Therefore, 177 grams of F are in the mixture.
What kind of reaction is this? C5H8 + 7O2 --> 5CO2 + 4H2O
A. Decomposition
B. Combustion
C. Single replacement
D. Combination
Answer:
B. Combustion .
Explanation:
Hello.
In this case, since this reaction is started by pentyne and oxygen which are converted to carbon dioxide and water, we can infer this is a combustion reaction because it involves the burnt of a fuel, in this case the pentyne, by using oxygen in order to yield carbon dioxide and water, which are smaller molecules than the original pentyne.
It is important to notice that these reactions are very exothermic because they go to break the C-H bonds in the fuel which release a considerably high amount of energy.
Best regards!
Which scientist determined that electrons had predicted zones orbiting the nucleus?
Rutherford
Bohr
Dalton
Schrödinger
Marthie
Answer:
Bohr
Explanation:
Neils Bohr was the scientist that suggested that electrons follow predictable orbits round the nucleus.
In 1913, he put forward his own model of the atom based on the quantum mechanics originally developed by Planck. He assumed the Rutherford's model and suggested that the extranuclear part consists of electrons in specific spherical orbits around the nucleus. The orbits/energy levels are designated as K, L, M, N.....Answer:
schrodinger
Explanation:
jelly benee
1. How is a covalent bond formed?
When electrons between atoms are transferred
When electrons between atoms are shared.
When electrons are subtracted from atoms.
When electrons are added to atoms.
