Answer:
[tex]A=275.1g[/tex]
Explanation:
Hello.
In this case, since the radioactive decay is computed via:
[tex]A=A_0*2^{-\frac{t}{t_{1/2}}[/tex]
For the initial amount of Ra-226 (300 g), once 200 years have passed, the remaining mass is:
[tex]A=300g*2^{-\frac{200years}{1600years}}\\\\A=275.1g[/tex]
This is, considering that the half-life is 1600 years, it means that the mass of Ra-226 is decreased.
Best regards.
How many total atoms are in 0.550 g of P2O5?
Answer:
Total atoms in 0.550g of =1.631x1022
Explanation:
answer is above
Two pieces of paper are stapled together.
Answer:
This is physical not chemical because a chemical example would be boiling water over the stove.
Explanation:
What was the average speed of the truck for this trip?
What is the same on the left and right side of a balanced equation? Explain your answer.
Answer:
Number of atoms of elements are same on left and right side of balance equation.
Explanation:
Every chemical reaction must follow the law of conservation of mass. According to which mass can neither be created nor destroy but it change from one to another form. It means mass remain conserved. That is why we need to balance the chemical equation because mass remain same on both side of equation. Consider the example,
Chemical equation:
N₂ + H₂ → NH₃
We can see that nitrogen and hydrogen react with each other and from ammonia. We need to balance the equation to have equal amount on both side.
Balance chemical equation:
N₂ + 3H₂ → 2NH₃
It means mass remain same but change from one to another form.
A balanced equation is one that is having a chemical reaction where the numbers of atoms. Here the number of elements in each reaction and the total charges are the same. This includes both the reactant and the product.
However, the mass and charge are balanced on both sides of the reaction. Hence the left and the right side is always equal to the number of atoms. Thus the chemical reaction is a balance of atoms involved in the reaction.Learn more about the same on the left and right sides of a balanced equation.
brainly.ph/question/20750343.
16. The diffusion rate of an unknown gas is measured to be 31.50 mL/min. Under
identical conditions, the diffusion rate of oxygen gas is measured to be 30.50
mL/min. Hint: diffusion rate is directly related to velocity.
Determine the identity of the unknown gas from the following options:
a. CH4
b. CO
C. NO
d. CO2
e. NO2
Answer:
Explanation:
[tex]\frac{r_1}{r_2} = \sqrt{\frac{M_2}{M_1} }[/tex]
r₁ and r₂ are rate of diffusion of gas having molecular mass of M₁ and M₂
[tex]\frac{31.5}{30.5} = \sqrt{\frac{32}{M_1} }[/tex]
1.0666 = 32 / M₁
M₁ = 30
molecular weight of NO = 14 + 16 = 30
So the unknown gas is NO .
3.
What are valence electrons? How do you quickly determine the number of valence electrons an
atom has?
Answer:
Electrons that arent electrons
Explanation:
I teach chem
Answer:
Valence electrons are the electrons found in the highest and main energy level of the atom, being these responsible for the interaction between atoms of different species or between atoms of the same species. You can quickly determine these by looking at a periodic table like this one... Which is where the roman numbers come in and show the valence electrons. (THIS TABLE IS IN SPANISH, I hope you still recognize the symbols.) :))
Which of the following is the metric system based on?
compare and contrast solids liquids and gases in terms of volume shape compessibility and energy
Answer:
solid has definite shape and volume.
liquid do not have definite shape but have definite volume.
gas do not have definite shape and definite volume.
solid have lowest compressibility out of three, liquid have more compressibility than solid but less than gases. gases have the highest compressibility out of three. Molecules in the solid phase have the least amount of energy, while gas particles have the greatest amount of energy. The temperature of a substance is a measure of the average kinetic energy of the particles.
__is a term that refers to the amount of space that a substance or an object takes up
how are compounds with metallic bonds similar to ionic compounds?
Answer:
Metals do not form double and triple bonds in general because metals want to lose electrons, not share, in order to become stable, and both compounds have high melting ppints
Compounds with metallic bonds and ionic compounds are similar in their melting point and boiling point, conductivity, solubility in polar solvents etc.
Ionic compounds are chemical compounds that are formed by the electrostatic attraction between oppositely charged ions.
Compounds with metallic bonds and ionic compounds are similar in several ways. Some of the similarities are:
1. High melting and boiling points: Both metallic and ionic compounds have high melting and boiling points due to the strong forces that hold the atoms or ions together.
2. Conductivity: Both metallic and ionic compounds are good conductors of electricity due to the presence of charged particles that can move freely.
3. Brittle: Ionic and metallic compounds are generally brittle in nature, meaning that they are prone to breaking or shattering when subjected to stress.
4. Solubility in polar solvents: Both metallic and ionic compounds are generally soluble in polar solvents such as water, due to the polar nature of the molecules.
In conclusion, compounds with metallic bonds and ionic compounds share several similarities. Both have high melting and boiling points, are good conductors of electricity, are brittle, and are generally soluble in polar solvents.
Learn more about ionic compounds here:
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if two successive terms of the fibonacci sequence are both odd, is the next term is even or odd? why?
Answer:
Even because you always add the previous two terms in the sequence. Since they are both odd, the next term will be even. (odd+odd = even)
Explanation:
2. How does friction effect speed?
Answer:
It acts as a force upon it like in newtons first law of motion an object in motion will stay in motion until a force acts upon it So friction bascicallly slows it down or stops it completly
Explanation:
Nervous tissue transmits messages throughout the human body by
contracting.
providing protection.
conducting impulses.
absorbing vital nutrients.
Answer: conducting impulses
Explanation:
just did it on edge
Answer:
c. conducting impulses.
Explanation:
got it right on edg, hope this helps!
Which statements about exothermic and endothermic reactions are correct? (its a multiple choice question)
1 During an exothermic reaction, heat is given out.
2 The temperature of an endothermic reaction goes up because heat is taken in.
3 Burning methane in the air is an exothermic reaction.
A) 1.2 and 3
B) 1 and 2 only
C) 1 and 3 only
D) 2 and 3 only
Answer:
C)1 and 3 only☺️
Explanation:
how did domestication of early crops start?
Answer:
In the Fertile Crescent in the Middle East, cereal crops were first domesticated about 11,000 years ago. Generally, the first domesticated crops were annuals with big seeds or fruits. ... Humans began to transition from a hunter-gatherer culture to a settled farming society as domestication took place.
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Hope this helps God bless!
What would happen if I throw nail polish remover into the fireplace
Answer:
Your house could catch fire because while Nail Polish Remover itself isn't particularly flammable, the vapors it gives off are. Because of this, sparks could occur if nail polish is used near open flame or was tossed in, and then the sparks could catch onto something else and grow. I would not recommend trying this.
Explanation:
How many elements are in H2CrO4
Answer:
3 elements
Explanation:
The elements are:
- Chromium
- Hydrogen
- Oxygen
True or false: An oxidation number is not the same as an actual charge on an ion. True false question. True False
Answer:
True
Explanation:
They are actually the same
The answer is False.
The oxidation number is the number of electrons removed or added to an element or compound. This is also equal to the charge on the ion.
For example, if Sodium atom loses one electron, it becomes oxidized to the + 1 state.
Na → Na⁺ + e⁻.
So, the oxidation number of Sodium is the charge on the Sodium ion which is + 1.
So, the oxidation number is equal to the charge on the ion.
So, the answer is False.
Learn more about oxidation number here:
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At what time was the frog sitting still or at rest
Answer:
What are the times and is that your question?
Explanation:
The thermite reaction occurs when iron(III) oxide reacts with solid
aluminum. The reaction is so hot that molten iron forms as a product.
>
Fe2O3(s) + Al(s) → Fe(C) + Al2O3(s)
What mass of aluminum should be used in order to completely
consume 10.0 g Fe2O3(s)? If the reaction described produces 5.3 g
Al2O3(s), what is the percent yield?
Answer:
[tex]m_{Al}=3.38gAl[/tex]
[tex]Y=83.1\%[/tex]
Explanation:
Hello.
In this case, for the given balanced reaction:
[tex]Fe_2O_3(s) + 2Al(s)\rightarrow 2Fe(s) + Al_2O_3(s)[/tex]
For 10.0 g of iron (III) oxide (molar mass = 160 g/mol), based on the 1:2 mole ratio with Al (atomic mass = 27 g/mol), the required mass is then:
[tex]m_{Al}=10.0gFe_2O_3*\frac{1molFe_2O_3}{160gFe_2O_3} *\frac{2molAl}{1molFe_2O_3} *\frac{27gAl}{1molAl} \\\\m_{Al}=3.38gAl[/tex]
Moreover, as 5.3 g of aluminum oxide are actually yielded, from the 10.0 g of iron (III) oxide, we can compute the theoretical mass of aluminum oxide (molar mass = 102 g/mol) via their 1:1 mole ratio:
[tex]m_{Al_2O_3}=10.0gFe_2O_3*\frac{1molFe_2O_3}{160gFe_2O_3} *\frac{1molAl_2O_3}{1molFe_2O_3} *\frac{102gAl_2O_3}{1molAl_2O_3} \\\\m_{Al_2O_3}=6.38gAl_2O_3[/tex]
Thus, the percent yield (actual/theoretical*100%) turns out:
[tex]Y=\frac{5.3 g}{6.38 g}* 100\%\\\\Y=83.1\%[/tex]
Best regards.
sharpining a pencil leaves behind pencil shavings. Is sharpining a pencil a physical change a physical or chemical? Explain
Answer:
A physical change
Explanation:
Cause when sharpening a pencil the led stays as led and only changes the height of it not the composition of it
I really need help on this
..
Answer:
b
Explanation:
Help me this, I only have 10 minutes to answer!!!!
Answer:sedimentary
Explanation:
an atom has 79 protons, 78 electrons and a mass number of 118. how many neutrons does this atom have
Answer:
39
Explanation:
Electrons weigh almost nothing, so their mass doesn't really matter for these types of problems. Just subtract 118-79 to find the remaining mass which is for the neutrons.
18. Which of these is an ion?
A. Fluorine with 9 protons
B. Calcium with 18 electrons
C. Calcium with 18 neutrons
D. Fluorine with 9 neutrons
A solution that holds more solute than it normally can under the conditions at a given temperature is _____. supersaturated unsaturated saturated diluted
Answer:
Supersaturated !
Explanation:
Calculate the atomic mass of the unknown element X described below.
Please help
Answer:
286
Explanation:
Add atomic mass of all the Isotopes,
Outcome = 825
divide it by number of isotopes which is 4 because there are 4 isotopes
Atomic mass of x = [tex]\frac{825}{4}[/tex]
Atomic mass of x is 286
The atomic mass of the unknown element X is 206 amu. Thus option B is correct.
What is atomic mass?Atomic mass is defined as the relative mass of the element's atom in comparison to the mass of an atom of the C12 isotope.
In an example, the general atomic mass is the average of the atomic masses of a large number of different isotopes.
First we added atomic mass of each isotopes
= 204 + 206 + 207 + 208 = 824
Now to calculate the atomic mass of element X we divide it by 4 as there is four isotopes
So, atomic mass = 824 / 4
= 206 amu
Thus, the atomic mass of the unknown element X is 206 amu. Thus option B is correct.
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In a certain chemical reaction, the bond energy of the products is 67 kJ and
that of the reactants is 52 kJ. Because energy is conserved, how much
potential energy does the system release or absorb?
O A. The reaction uses up 15 kJ of energy from the reaction system.
B. The reaction creates 15 kJ of energy when bonds form.
C. The reaction system absorbs 15 kJ of energy from the
surroundings.
O D. The surroundings absorb 15 kJ of potential energy.
D. The surroundings absorb 15 kJ of potential energy.
Further explanationChemical bonds = potential energy
ΔH reaction from bond energy is a breaking and forming reaction of the 2 reacting molecules
Can be formulated:
ΔH rxn = ∑ the energy of the reagent bonds broken - ∑ the energy of the bonds formed by the product
The bond energy of the products is 67 kJ and reactants 52 kJ
[tex]\tt \Delta H_{rxn}=52-67=-15~kJ[/tex]
ΔH = negative ⇒The reaction is exothermic(releases heat to surrounding)
Answer:
C is right
Explanation:
What type of compound is iron(III) oxide?
Group A metal ionic compound with nonmetal anion
Group A metal ionic compound with polyatomic anion
transition metal ionic compound with polyatomic anion
transition metal ionic compound with nonmetal anion
Answer:transition metal ionic compound with nonmetal anion
Explanation:
Answer:
Your answer is going to be D. transition metal ionic compound with nonmetal anion
Hope this helps :)
What is the temperature, in degrees Celsius, of a 10.5 grams sample of Neon gas confined to a volume of 2.50 L at a pressure of 1.00 atm.
Answer:
–215 °C
Explanation:
From the question given above, the following data were obtained:
Mass of Ne = 10.5 g
Volume (V) = 2.50 L
Pressure (P) = 1 atm
Temperature (T) =?
Next, we shall determine the number of mole present in 10.5 gof Neon, Ne. This can be obtained as follow:
Mass of Ne = 10.5 g
Molar mass of Ne = 20 g/mol
Mole of Ne =.?
Mole = mass /Molar mass
Mole of Ne = 10.5 / 20
Mole of Ne = 0.525 mole
Next, we shall determine the temperature of the sample of Neon, Ne. This can be obtained as follow:
Volume (V) = 2.50 L
Pressure (P) = 1 atm
Number of mole (n) = 0.525 mole
Gas constant (R) = 0.0821 atm.L/Kmol
Temperature (T) =?
PV = nRT
1 × 2.5 = 0.525 × 0.0821 × T
2.5 = 0.525 × 0.0821 × T
Divide both side by 0.525 × 0.0821
T = 2.5 / (0.525 × 0.0821)
T = 58 K
Finally, we shall convert 58 K to degree celsius (°C). This can be obtained as follow:
T(°C) = T(K) – 273
T(K) = 58 K
T(°C) = 58 – 273
T(°C) = –215 °C
Thus, the temperature of the sample of Neon gas is –215 °C.