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:
C
Explanation:
I got this question right on my test.
A sugar cube was placed into a beaker containing 100 mL of water at room temperature and completely dissolved into the water. This process is represented by the series of diagrams labeled A, B, and C below. Describe one way that the dissolved sugar at C could be separated from the water.
Answer:
Boil the water until it evaporates
Explanation:
If the water evaporates the sugar will no longer bond to it and then percipitate at the bottom of the beaker.
Select the correct answer.
What is the molecularity of this elementary step?
A+ A+B-->C+D
A.
unimolecular
B.
bimolecular
c.
trimolecular
D.
tetramolecular
Answer: C not really sure thoo
advantages
of corrosion
Answer:
Protection : Surface corrosion forms an oxide layer which further protects the inner metal form corrosion
.
Corrosion prevents corrosion : Some metals like zinc are used as sacrificial anodes to prevent corrosion to other metal.
Galvanic corrosion : The principle on which primary batteries work.
What is the best way to reduce water pollution
Answer: Pick up litter and throw it away in a garbage can.
Blow or sweep fertilizer back onto the grass if it gets onto paved areas. ...
Mulch or compost grass or yard waste. ...
Wash your car or outdoor equipment where it can flow to a gravel or grassed area instead of a street.
Don't pour your motor oil down the storm drain.
HOPE THIS HELPS
4. Calculate the final temperature of 75.4 g water originally at 12.6 °C after it absorbs 3.85 kcal
of heat.
Answer:
63.7 °C
Explanation:
Step 1: Given and required data
Mass of water (m): 75.4 gInitial temperature (T₁): 12.6 °CAbsorbed heat (Q): 3.85 kcalSpecific heat capacity of water (c): 1 cal/g.°CStep 2: Calculate the final temperature of the water (T₂)
We will use the following expression.
Q = c × m × (T₂ - T₁)
T₂ = Q/c × m + T₁
T₂ = 3.85 × 10³ cal/(1 cal/g.°C) × 75.4 g + 12.6 °C = 63.7 °C
classify each of the following reactions when only the reactants are given and fill in the products.
explain your answer for brainliest.
Answer:
CO2 + MgO
Explanation:
We want the number of each element on the Reactants (Left side) to be equal to the number of each element on the Product side (Right side).
Help me out with those two letters pls
Answer:
F. 1, 1
G. 1
Explanation:
When you work out how many there are of each thing, the numbers that were already in there equal each other, do you just need to add ones in the other blanks.
A conversion factor is a fraction in which the numerator is equal to the denominator.
a. True
b. False
Answer:
A
Explanation:
A conversion factor is a fraction whose numerator and denominator are the same quantity expressed in different units.
The given statement that a conversion factor is a fraction in which the numerator is equal to denominator is true.
What is a conversion factor?
Conversion factor is an expression which is used for obtaining relationship between units of a measurable quantity without any need of changing the value.It is also known as unit factor and is always equal to one.
Here the numerator represents part out of the whole portion .While the denominator represents the total number of parts.The method is based on the fact that any number or an expression can be multiplied by one without changing it's value.
As the multiplication by one does not change the value of measurement and so there is no change in the measurement units.It is a formula used for converting a measurement in one set of units to same measurement in another set of units.
It is usually given as a numerical ratio or fraction which can be used as a multiplication factor. Some examples of measurements which require conversions are: length,area and volume.
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What is likely to happen to the trees if the trend continues?
Answer:
Trees could go extinct and people could die.
Explanation:
The formula for the pH of a solution of hydronium ions is given by the logarithmic equation pH= -log[h3o^+], where [H3o^+] is the hydronium ion concentration. Find the pH of a certain agricultural product with the hydronium ion concentration of 4.7x10^-4
The pH is =?
Answer:
pH = 3.3
Explanation:
Step 1: Given data
Concentration of hydronium ions in the agricultural product ([H₃O⁺]): 4.7 × 10⁻⁴ M
Step 2: Calculate the pH of the agricultural product
We will use the definition of pH.
pH = -log [H₃O⁺]
pH = -log 4.7 × 10⁻⁴
pH = 3.3
Since the pH < 7, the agricultural product is acidic.
lonic bonding can only occur between which two types of elements
a
Metal and metal
b
non metal and non metal
c
metal and non metal
d
none of the above
Answer:
C.
Explanation:
An ionic bond is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions. Ionic bonds are formed between a cation, which is usually a metal, and an anion, which is usually a nonmetal. A covalent bond involves a pair of electrons being shared between atoms.
What are all of the mole ratios of MgCl2 -> Mg+ Cl2
Answer:
2 moles
In words, 1 mole of Mg reacts with 2 moles of HCl to form 1 mole of MgCl₂ and 1 mole of H₂. The molar ratio of HCl to MgCl₂ is 2:1.
Which agent of erosion is probably at work in the area
1. Identify the seven diatomic elements and explain why they are different from the rest of the elements
Answer:
hydrogen, nitrogen, oxygen, flourine, chlorine, iodine, bromine
Explanation:
they are very reactive and thus cannot exist as monoatomic elements
The seven diatomic elements are;
HydrogenOxygenChlorineFlourineIodineBromineNitrogenAccording to the question;
We are required to identify the seven diatomic elements and explain why they are different from the rest of the elements.The diatomic elements as listed above are different from the rest of the elements in that they exist as molecules.
This is as a result of the high electron affinity of these elements. Consequently, they form molecules with atoms of themselves.
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7. Calculate moles of H2 needed to form 2.25 moles HCl in the reaction H2 + Cl2==>2HCl
Answer:
1.125 moles
Explanation:
2mole of HCl produced 1mole of H2
2.25moles of HCl will produce x moles
cross multiply
2x=™1×2.25
x= 2.25÷2
x=1.125mole
PLS HELPP!!!!! A type of waves that carries energy from one place to another, even through empty space is:
A. Amplitude
B. Wave
C. Light
D. Energy
Answer: The answer is C light pretty obvious.
Explanation:
A type of waves that carries energy from one place to another, even through empty space is Light. therefore, option C is correct.
Which kind of waves carry energy from one place to another?Waves can move energy between locations, they do not always move mass. Common examples of waves are light, sound, and ocean waves. Since sound and water waves are mechanical waves, they must move via a medium.
Waves that can pass across the vacuum of space are electromagnetic waves. Unlike electromagnetic waves, mechanical waves must travel through a material medium in order to transfer energy from one place to another.
Electromagnetic waves that are light waves, can move energy both through matter and through space.
Thus, A type of waves that carries energy from one place to another, even through empty space is Light, option C is correct.
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Fish breathe the dissolved air in water through their gills. Assuming the partial pressures of oxygen and nitrogen in air to be 0.20 atm and 0.80 atm, respectively, calculate the mole fractions of oxygen and nitrogen in water at 298 K. Comment on your results
Answer:
X(O₂) = 0.323
X(N₂) = 0.677
Explanation:
We have the partial pressures of oxygen (O₂) and nitrogen (N₂):
P(O₂) = 0.20 atm
P(N₂) = 0.80 atm
In order to solve the problem, you need the solubilities of each gas in water at 298 K. We can consider 1.3 x 10⁻³ mol/(L atm) for oxygen (O₂) and 6.8 x 10⁻⁴mol/(L atm) for nitrogen (N₂) from the bibliography.
s(O₂) = 1.3 x 10⁻³ mol/(L atm)
s(N₂) = 6.8 x 10⁻⁴mol/(L atm)
So, we calculate the concentration (C) of each gas as the product of its partial pressure (P) and the solubility (s):
C(O₂) = P(O₂) x s(O₂) = 0.20 atm x 1.3 x 10⁻³ mol/(L atm) = 2.6 x 10⁻⁴mol/L
C(N₂) = P(N₂) x s(N₂) = 0.80 atm x 6.8 x 10⁻⁴mol/(L atm) = 5.44 x 10⁻⁴ mol/L
In 1 liter of water, we have the following number of moles (n):
n(O₂) = 2.6 x 10⁻⁴ mol
n(N₂) = 5.44 x 10⁻⁴ mol
Thus, the total number of moles (nt) is calculated as the sum of the number of moles of the gases in the mixture:
nt = n(O₂) + n(N₂) = 2.6 x 10⁻⁴ mol + 5.44 x 10⁻⁴ mol = 8.04 x 10⁻⁴ mol
Finally, the mole fraction of each gas is calculated as the ratio between the number of moles of each gas and the total number of moles:
X(O₂) = n(O₂)/nt = 2.6 x 10⁻⁴ mol/(8.04 x 10⁻⁴ mol) = 0.323
X(N₂) = n(N₂)/nt = 5.44 x 10⁻⁴ mol/(8.04 x 10⁻⁴ mol) = 0.677
The frequency of a wave does not change as it passes from one medium to another.
What will most likely happen if a light wave moves from the air into a solid?
The wavelength of the light wave will increase.
The speed of the light wave will decrease.
The wavelength of the light wave will remain the same.
The speed of the light wave will remain the same.
(in subject a put chemistry cause there was no science, the subject is science)
Answer:
it will decrease
Explanation:
on test. have a nice day
Answer:
I think it is c
Explanation:
What will happen If CH4 is added to the following reaction at equilibrium CH4 (g) + 2H2O (g) <------> 3H2 (g) + CO2 (g)
1. reaction will shift to the the right and the concentration of CO2(g) will decrease
2. reaction will shift to the the right and the concentration of CO2(g) will increase
3. reaction will shift to the the left and the concentration of CO2(g) will decrease
4. reaction will shift to the the left and the concentration of CO2(g) will increase
Answer:
the answer is D
:)
:D
Explanation:
HOW MANY MOLES OF CS2 FORMS WHEN 2.7 MOLE C REACTS
How many liters of water can be made from 55.0 grams of oxygen gas and an excess of
hydrogen at STP?
PLZ HELP *NO LINKS*
1) How many moles of gaseous arsine (AsH3) occupy 0.372 L at STP?
In sig fig 4
2) What is the density of gaseous arsine?
In sig fig 4
Thanks!
Answer: (1). There are 0.0165 moles of gaseous arsine (AsH3) occupy 0.372 L at STP.
(2). The density of gaseous arsine is 3.45 g/L.
Explanation:
1). At STP the pressure is 1 atm and temperature is 273.15 K. So, using the ideal gas equation number of moles are calculated as follows.
PV = nRT
where,
P = pressure
V = volume
n = number of moles
R = gas constant = 0.0821 L atm/mol K
T = temperature
Substitute the values into above formula as follows.
[tex]PV = nRT\\1 atm \times 0.372 L = n \times 0.0821 L atm/mol K \times 273.15 K\\n = 0.0165 mol[/tex]
2). As number of moles are also equal to mass of a substance divided by its molar mass.
So, number of moles of Arsine [tex](AsH_{3})[/tex] (molar mass = 77.95 g/mol) is as follows.
[tex]No. of moles = \frac{mass}{molar mass}\\0.0165 mol = \frac{mass}{77.95 g/mol}\\mass = 1.286 g[/tex]
Density is the mass of substance divided by its volume. Hence, density of arsine is calculated as follows.
[tex]Density = \frac{mass}{volume}\\= \frac{1.286 g}{0.372 L}\\= 3.45 g/L[/tex]
Thus, we can conclude that 0.0165 moles of gaseous arsine (AsH3) occupy 0.372 L at STP and the density of gaseous arsine is 3.45 g/L.
What is the mass of 4.76 moles of Na3Po4?
SHOW WORK PLEASE - NO LINKS OR FILES(I will not open them)
( btw if you sent a link do not answer , I have already reported your accounts )
Answer:
780.354g
Explanation:
22.99(3)+30.97+16(4)
=163.94g/mol
163.94*4.76=780.354g...
PLEASE HELP ME !!!! !!!!
Answer:
180-115-31=34
earth has a low air pressure zone at the equator because what
Question 3 of 10
Which best explains why the sun maintains its size and shape?
A. Pressure caused by high temperatures are balanced by gravity.
B. The sun burns from its core to its surface.
C. Forces exerted by orbiting planets cause the sun to rotate.
SUBMIT
Answer:A
Explanation:
HELP HELP HELP!!!!!!!!!!
the answer will there for be ironic
Which of the following is a powerful antioxidant?
a. free radicals
b. bleach
c. peroxide
d. vitamin C
jacket
А
in
Liquid C
ka
Name the method of separation of the mixture.
Liquid 'C' was formed when the mixture was heated at 7
What is liquid 'C'.
Name the substance that remains in the flask after 78°C.
State the function of the thermometer and the water ja
What is the other name of the water jacket.
Sorry but I don't know
Explanation:
I just want points sorry