A sample of polonium-210 has an initial mass of 390 milligrams (mg). If the half-life of polonium-210 is 36 days, how many mg of the sample remains after 72 days?
A.
392 mg
B.
195 mg
C.
97.5 mg
D.
48.75 mg
Answer: D. 48.75
Explanation: just took the test
Answer:
D
Explanation:
I got this question right on my test.
Becky wants to model an ecosystem. Which of the following modeling tools would best help her illustrate an ecosystem?
A.
a rubber ball
B.
a terrarium
C.
a map
D.
a set of building blocks
Answer:
c
Explanation:
what is the definition for domain bacteria?
Answer:
Domain is the............. highest taxonomic rank in the hierarchical biological classification system, ........above the kingdom level. There are three domains of life, the Archaea, the Bacteria,,,,,,,,, and the Eucarya.
Reword, taken off the internet.
Explanation:
How many kilojoules of energy are required to heat 50.0 g of ethyl alcohol from 60.0 °C to 78.4 °C and vaporize it? The specific heat of ethyl alcohol is 2.138 J/g°C; heat of vaporization is 853 J/g.
Answer:
44.62 kJ
Explanation:
Firstly, we calculate the energy needed to heat the liquid (ethyl alcohol) by using the formula:
Q = m × c × ∆T
Where;
Q = Amount of heat (J)
m = mass (g)
c = specific heat of ethyl alcohol = 2.138 J/g°C
∆T = change in temperature (°C)
According to the information given in this question;
Q = ?, m = 50.0g, ∆T = (78.4°C - 60°C) = 18.4°C
Therefore, using Q = mc∆T
Q = 50 × 2.138 × 18.4
Q (amount of energy needed to heat ethyl alcohol) = 1966.96 J
Next, we calculate and add the amount of heat needed to vaporize by using the formula;
How many kilojoules of energy are required to heat 50.0 g of ethyl alcohol from 60.0 °C to 78.4 °C and vaporize it? The specific heat of ethyl alcohol is heat of vaporization is 853 J/g.
Think about the decomposition reaction of ozone.
2 O3 ----> 3 O2
If 71.7 mol ozone are in this reaction, what is the theoretical yield of O2 (in gram)?
Answer:
3441.6 grams.
Explanation:
2 O₃ → 3 O₂
First we convert 71.7 moles of ozone (O₃) into moles of oxygen gas (O₂), using the stoichiometric coefficients of the reation:
71.7 mol O₃ * [tex]\frac{3molO_2}{2molO_3}[/tex] = 107.55 mol O₂
Then we convert 107.55 moles of O₂ into grams, using the molar mass of O₂:
107.55 mol * 32 g/mol = 3441.6 g
How many liters of solvent are are required to make a 5.34 M solution using 12.52
mol of solute?
1. Density is the measure of how much
volume ?????? is contained in a given volume
Explanation:
Density is the mass of an object divided by its volume. Density often has units of grams per cubic centimeter (g/cm3). Remember, grams is a mass and cubic centimeters is a volume (the same volume as 1 milliliter).
You can follow me to get more answer.
_____ is the process of linking smaller molecules to form long chains of higher molecular weight.
What is the pOH for a solution whose pH is 2?
Answer:
12
Explanation:
Because it is pH and pOH, you can use the relationship of 14-pH=pOH, or 14-pOH=pH. Using this you should get the pOH to be 12.
What happens when earth rotates on its axis and how long take?
Answer:
We get Day and Night... It takes 24 hours for the earth to rotate on its axis
What is the difference between how a mercury barometer and an aneroid barometer measure air pressure?
Answer:
Aneroid barometer and mercury barometer are such two types. The main difference between aneroid and mercury barometer is that aneroid barometer measures the atmospheric pressure using the expansion of a metal whereas mercury barometer measures the atmospheric pressure by adjusting the height of mercury inside a tube.
Explanation:
8. Which of the following elemental gases would have properties closest to an ideal gas?
a. hydrogen
argon
b. helium
d. fluorine
Answer:
Helium
Explanation:
Please tell me if it was right
The half-life for a 400-gram sample of radioactive element X is 3 days. How much of element X remains after 15 days have passed?
A.
12.5 g
B.
25 g
C.
50 g
D.
100 g
Answer:
The correct answer is - A. 12.5 gram.
Explanation:
Given:
The initial amount of sample = 400 gram
the half-life cycle = 3 days
after 15 days remain value = ?
Solution:
The number of half-lives in 15 days = 15/3
= 5 half-lives
the remaining amount of sample after one half-life 3 days = 400/2 = 200
the remaining amount of sample after 2nd half-life or 6 days= 200/2 = 100
the remaining amount of sample after 3rd half-life or 9 days= 100/2 = 50
the remaining amount of sample after 4th half-life or 12 days= 50/2 = 25
the remaining amount of sample after 5th half-life or 15 days= 25/2 = 12.5 gram
Thus, the correct answer is = 12.5 g.
Which statement best defines the term innate behavior?
behavior that is taught through watching others
behavior that is simple, untaught, and born knowing
behavior that is taught through both good and bad experiences
behavior that is untaught but very complex
Answer: behavior that is simple, untaught, and born knowing
Have a nice dam day!!
The term that describes innate behavior is:
D. behavior that is untaught but very complex
What does innate behavior stand for?Intr-insic or "intuitive" ways of behaving are innate and don't need learning or related knowledge to be performed. Models incorporate romance and ways of behaving, departure and guarded moves, and hostility. Movement and Migration Innate or ins-tinctual behaviors rely on response to sti-muli.
Thus, option D is correct.
Find more information about Innate behavior here:
brainly.com/question/14311636
What is true of an earthquake that causes major damage to buildings in an area?
It has a high magnitude.
It has a high frequency.
It has a low frequency.
It has a low magnitude.
The correct option is :
=》It has a high magnitude.
the damage caused by an earthquake is proportional to its magnitude, as much the magnitude is, that much damage will be caused by it.
The term used to indicate and earthquake that causes major damage to buildings in an area is called a high magnitude earthquake. Hence, option a is correct.
What is high magnitude earthquake?The most typical way to gauge an earthquake's size is by its magnitude. No matter where you are or how violent the shaking is, it is the same number since it represents the size of the earthquake's source.
The USGS no longer uses the outmoded Richter scale to determine the magnitude of major, teleseismic earthquakes. Several magnitude scales measure various aspects of the earthquake, but the Richter scale measures the biggest wobble (amplitude) on the recording.
Currently, the USGS uses the Moment Magnitude scale to report earthquake magnitudes, however many different magnitudes can be calculated for comparison and research. Therefore, option a is correct.
Find more on earthquakes:
https://brainly.com/question/29500066
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How many moles are in 9.83 x 1021 atoms of Na
Answer:
0.016 molesExplanation:
To find the number of moles in a substance given it's number of entities we use the formula
[tex]n = \frac{N}{L} \\[/tex]
where n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10²³ entities
We have
[tex]n = \frac{9.83 \times {10}^{21} }{6.02 \times {10}^{23} } \\ = 0.01632...[/tex]
We have the final answer as
0.016 molesHope this helps you
Genes influence an organism's traits by coding for:
A
Cells
Answer:
First, the protein may be a structural protein, contributing to the physical properties of cells or organisms. ... Second, the protein may be an enzyme that catalyzes one of the chemical reactions of the cell. Therefore, by coding for proteins, genes determine two important facets of biological structure and function.
Explanation:
i think it will help you
Group 1 substances are called ionic compounds and Group 2 substances are called covalent molecules. Write a
simple rule that will allow you to classify compounds as ionic or covalent on the basis of what you have learned
from the model
Answer:
An ion found in some compounds used as antiperspirants contains 13 protons and 10 electrons. What is its symbol?
Solution
Because the number of protons remains unchanged when an atom forms an ion, the atomic number of the element must be 13. Knowing this lets us use the periodic table to identify the element as Al (aluminum). The Al atom has lost three electrons and thus has three more positive charges (13) than it has electrons (10). This is the aluminum cation, Al3+.
How many grams of N2 is needed to produce 2000 grams NH3?
Answer:
1644 g
Explanation:
Step 1: Write the balanced equation
N₂ + 3 H₂ ⇒ 2 NH₃
Step 2: Calculate the moles corresponding to 2000 g of NH₃
The molar mass of NH₃ is 17.03 g/mol.
2000 g × 1 mol/17.03 g = 117.4 mol
Step 3: Calculate the moles of N₂ needed to produce 117.4 moles of NH₃
The molar ratio of N₂ to NH₃ is 1:2. The moles of N₂ needed are 1/2 × 117.4 mol = 58.70 mol
Step 4: Calculate the mass corresponding to 58.70 moles of N₂
The molar mass of N₂ is 28.01 g/mol.
58.70 mol × 28.01 g/mol = 1644 g
what is the chemical equation for aq nitrate ion reacts with s arsenic trihydride and produces s arsenic and g ammonia?
Answer:
Explanation:
Excessive use of chemical fertilizer causes chemical pollution.how?
Answer:
Chemical fertilizers contain various chemicals that cause harm to soil and water.
Explanation:
Chemical fertilizers contain various chemicals such as phosphates, nitrates which can cause water pollution. Eutrophication caused by the environmental nitrogen and phosphorous that causes rich minerals and chemicals in the water.
These can cause excessive growth of the algae and phytoplankton that will cause depletion of the oxygen from the water body and organisms will die due to this.
How do children use food molecules to grow taller?
Options
A - Children grow taller when they use food molecules they eat to build large molecules that make up new cells.
B - Children grow taller when they use the food molecules they eat to make up new cells without changing the food molecules.
C - Children grow taller when they use the energy from the food molecules, but all of the molecules leave the body as waste.
D- Children grow taller when they store food molecules as fat.
A or B or C Or D ?
Answer:
C) Children grow taller when they use the energy from the food molecule, but all of the molecules leave the body as waste.
hope it helps.
Answer:
C - Children grow taller when they use the energy from the food molecules, but all of the molecules leave the body as waste.
hope it is helpful to you ☺️☺️☺️☺️
[H3O+] = 2.9 x 10-10 M
ph level
Answer:
9.54
Explanation:
Fr the question given above, the following data were:
Concentration of hydronium ion [H3O⁺] = 2.9x10¯¹⁰ M
pH =?
The pH of the solution can be obtained as follow:
pH = –Log [H3O⁺]
pH = –Log 2.9x10¯¹⁰
pH = 9.54
Thus, the pH level of the solution is 9.54
the amount of thermal energy stored in an object depends on what
Answer:
The amount of thermal energy stored in an object depends on three things.
The mass of the object.The temperature of the object. The amount of energy that the particular material stores per degree of temperature.
What is the name for the compound with a chemical formula B6Si.
The chemical formula B₆Si belongs to the compound silicon hexaboride.
ii) Sodium thiosulphate dissolves in dilute nitric acid at a steady rate. Copy out which
of the following changes would quicken up the reaction- 3
a. Cooling the reacting vessel to drop the temperature.
b. Breaking the reactants into smaller pieces.
c. Adding more concentrated acid.
d. Using more sodium thiosulphate.
Answer:
d
Explanation:
the element with atomic number 35 belongs to
Which of the two Lewis/electron dot structure representations, which is
the correct one for oxygen gas? PICTURE BELOW
Answer:
A
Explanation:
Calculate the value of Delta H for the reaction CaCO3 --> CO2 + CaO from the following enthalpy changes:
Ca + C + 3/2 O2 --> CaCO3 ΔH = -1206.9 kJ
Ca + ½ O2 --> CaO ΔH = -635.1 kJ
C + O2 -->CO2 ΔH= - 393.5 kJ
Explanation:
crescents discuss wentz eg
Answer:
2,2,1,2
2 Ca + 2 CO2 + 1 O2 → 2 CaCO3
Explanation:
Got it right on Oddesyware!!!!
What is the oxidation state of S in S2O32−?
A. +3 B. +2 C. –2 D. +4
Answer:
it'd be +2
Explanation:
Since 3 atoms of oxygen are present, so its combined oxidation number will be3(−2)=−6. Now this ion contains a charge of−2, where the sum of the oxidation number of all atoms in an atom is equal to−2. So the oxidation number of S in S2O2−3 should be +2.