Uranium-235 has a half-life of 710 million years. If it is determined that a certain amount of stored U-235 will be considered safe only when its radioactivity has dropped to 0.10 percent of the original level, approximately how much time must the U-235 be stored securely to be safe?

(A) 7.1 x 10^6 years
(B) 7.1 x 10^7 years
(C) 7.1 x 10^8 years
(D) 7.1 x 10^9 years
(E) 7.1 x 10^10 years

Given its lack of a definite crystal structure, Marcie's shiny rock is likely a rock, not a mineral. Rocks are comprised of various minerals and other materials, which results in a less distinct structure compared to minerals.

Marcie's shiny rock is likely a rock, given its description. Rocks and minerals, while sharing some characteristics, have key differences. Both rocks and minerals are solid, naturally occurring substances. However, minerals, besides having a definite chemical composition, also possess a specific crystal structure. By confirming that Marcie's shiny rock does not have a definite crystal structure, it's safer to categorize it as a rock. Rocks are comprised of different minerals as well as other elements, making them less uniform than minerals. Rocks range from three basic types: igneous (from molten rock or lava), sedimentary (from the deposition and sedimentation of organic or inorganic particles), and metamorphic rock (undergone chemical alteration under high temperature and pressure).

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Marcie's rock is likely a rock, not a mineral, due to its lack of a definite crystalline structure. Although certain rocks with metallic content can be extraterrestrial, no indication is given to suggest this. The rock could be classified as metamorphic, sedimentary, or igneous, depending on its formation process.

Marcie's shiny rock, being solid, naturally occurring, and possessing a definite chemical composition, meets most criteria to be termed a mineral. However, a key aspect of a mineral is that it exhibits a definite crystalline structure, which her rock does not. Hence, it would better be described as a rock. Rocks can be an amalgamation of different minerals and do not require a specific crystalline structure to classify.

The identified characteristics of the rock, however, do not necessarily mean it is extraterrestrial in origin, as the provided references might suggest. While it is true that the irons and stony-irons with metallic content can be extraterrestrial, there is no indication given that Marcie's rock is metallic or contains iron. Therefore, it is unlikely a meteorite. It may require a laboratory analysis to confirm this.

It may be a metamorphic, sedimentary, or igneous rock, which are categories based on their geologic formation processes. Metamorphic rocks undergo physical and chemical alteration under high temperature and pressure, sedimentary rocks are formed from the sedimentation of particles, and igneous rocks originate from the solidification of magma or lava.

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Answer:

Acid: [Al(H₂O)₆]³⁺

Base: H₂O

Conjugate base: [Al(H₂O)₅(OH)]²⁻

Explanation:

(a) For the reaction:

[Al(H₂O)₆]³⁺  + H₂O  ⇄  H₃O⁺ + [Al(H₂O)₅(OH)]²⁻

The acid: [Al(H₂O)₆]³⁺

The base: H₂O

The conjugate base: [Al(H₂O)₅(OH)]²⁻    

According to the Bronsted-Lowry acid-base theory, the reaction of an acid and base occurs by the exchange of a proton. The acid forms its conjugate base, and the base forms its conjugate acid in the reaction.

Hence, by the above definition, the [Al(H₂O)₆]³⁺ is the acid that forms its conjugate base [Al(H₂O)₅(OH)]²⁻ and the H₂O is the base that forms its acid conjugate H₃O⁺ when they react and the  [Al(H₂O)₆]³⁺ lose a proton to the H₂O.  

I hope it helps you!

Answer:

Sulphur is the element having atomic number 16. Its valency is 6 and forms anion.

Explanation:

Sulphur is the element having atomic number 16 and mass number 32 which means sulphur has 16 proton, 16 electron and 16 neutron. 2 electrons are present in the first shell, 8 electrons are present in the second shell and 6 electrons are present in the outermost shell. Sulphur requires 2 electrons to become stable so that's why sulphur take 2 electrons and become anion. its valency is 6 which means 6 electrons are present in the outermost shell of sulphur atom.

Answer:

Mass of Mg(OH)₂ required for the reaction = 863.13 g

Explanation:

3Mg(OH)₂ + 2H₃PO₄ -------> Mg₃(PO₄)₂ + 6H₂O

(5.943 x 10²⁴) molecules of H₃PO₄ is available fore reaction. Mass of Mg(OH)₂ required for reaction.

According to Avogadro's theory, 1 mole of all substances contain (6.022 × 10²³) molecules.

This can allow us find the number of moles that (5.943 x 10²⁴) molecules of H₃PO₄ represents.

1 mole = (6.022 × 10²³) molecules.

x mole = (5.943 x 10²⁴) molecules

x = (5.943 x 10²⁴) ÷ (6.022 × 10²³)

x = 9.87 moles

From the stoichiometric balance of the reaction,

2 moles of H₃PO₄ reacts with 3 moles of Mg(OH)₂

9.87 moles of H₃PO₄ will react with y moles of Mg(OH)₂

y = (3×9.87)/2 = 14.80 moles

So, 14.8 moles of Mg(OH)₂ is required for this reaction. We them convert this to mass

Mass = (number of moles) × Molar mass

Molar mass of Mg(OH)₂ = 58.3197 g/mol

Mass of Mg(OH)₂ required for the reaction

= 14.8 × 58.3197 = 863.13 g

Hope this Helps!!!

Answer:

5.943 × 10²⁴ molecules of H₃PO₄ will react with 789.29 grams of  Mg(OH)₂

Explanation:

Here we have

5.943 × 10²⁴ molecules of H₃PO₄ in a reaction with Mg(OH)₂

as follows

3Mg(OH)₂ + 2H₃PO₄ → Mg₃(PO₄)₂ + 6H₂O

Therefore 3 moles of Mg(OH)₂ react with 2 moles of H₃PO₄ to form 1 mole of Mg₃(PO₄)₂ and 6 moles of H₂O

5.943 × 10²⁴ molecules of H₃PO₄ which is equivalent to [tex]\frac{5.943 \times 10^{24}}{6.02 \times 10^{23}} moles = 9.869 \, moles \, of \, H_3PO_4[/tex]

Will react with 3/2×9.869 moles or 14.8 moles of Mg(OH)₂

One mole of Mg(OH)₂ weighs 58.3197 g/mol

Therefore, 5.943 × 10²⁴ molecules of H₃PO₄ will react with 14.8×58.3197 g or 789.29 grams of  Mg(OH)₂.

Answer:

C= 0.532M

Explanation:

The equation of reaction is

H2SO4 + 2KOH = K2SO4+ H2O

nA= 1, nB= 2, CA= ?, VA= 48.9ml, CB= 1.5M, VB= 34.7ml

Applying

CAVA/CBVB = nA/nB

(CA× 48.9)/(1.5×34.7)= 1/2

Simplify

CA= 0.532M

Answer:

0.425

Explanation:

Answer:

0.452

Explanation:

Answer:

Liquid drain cleaner: Base

Milk: Acid

Explanation:

Would make sense to see this on the pH scale where anything above 7 is basic and below 7 is acidic.

The identification of each substance treated as an acid or substance should be Liquid drain cleaner: Base and Milk: Acid

Acid should be treated as the hydrogen that contained the substance where the proton should be donated to the other substance. While on the other hand, the base represent the molecule for accepting the hydrogen ion from an acid. Also if the pH scale should be above 7 so it should be treated base while below should be treated as the acid.

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Answer:

Most common oxidation state of the chalcogens is -2, most common oxidation state of the halogens is -1.

Explanation:

For atomic radii, the chalcogens have a larger atomic radii than the halogens

This is because atomic radii decreases across the period due to increase in nuclear charge.

For ionic radii the chalcogens also have larger ionic radii than the halogens. This is because the chalcogens always carry a -2 charge compared to halogens that carry a -1 charge. Since -2 is the most common oxidation state for chalcogens and -1 is the most common oxidation state for the halogens.

In terms of oxidation states, the halogens show a higher value of common oxidation state -1 while for chalcogens is -2 even though +2, +4 and +6 oxidation states are also well known.

First ionization energy of halogens is greater than that of the chalcogens due to greater effective nuclear charge.

The second ionization energy of chalcogens is greater than that of the halogens.

Chalcogens have −2, +2, +4, and +6 whereas halogens have −1, +1, +3, +5, and +7 oxidation state.

The most common oxidation states of the elements of chalcogens are −2, +2, +4, and +6 while on the other hand,  the oxidation states of halogens such as fluorine, chlorine, bromine, and iodine are −1, +1, +3, +5, and +7. The chalcogens have larger atomic as well as ionic radii as compared to halogens because of the presence of less number of electrons in the outermost shell.

We know that when we moves from left to right in the periodic table, atomic radius decreases due to addition of extra electrons in the outermost shell. The attraction of nucleus on the additional electron increases which leads to movement of outermost shell nearer to nucleus.

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Answer: 0.029 mol

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.

The balanced chemical equation is:

[tex]C_{12}H_{22}O_{11}+12O_2\rightarrow 12CO_2+11H_2O[/tex]

To calculate the moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar Mass}}=\frac{10.0g}{342g/mol}}=0.029moles[/tex]

Thus there are 0.029 moles of sucrose

Answer:

A

Explanation:

Answer:

0.083 moles KCl

Explanation:

We have 252 mL of 0.33 M KCl. "M" is molarity, and it's measured in mol/L. Since we know the molarity is 0.33 mol/L, in order to find how many moles 252 mL is, we need to multiply our given volume by the molarity.

However, our given volume is in mL, so let's convert to L first by dividing 252 by 1000 (because there are 1000 mL in 1 L):

252/1000 = 0.252 L

Now, we can multiply 0.252 L by 0.33 mol/L to get moles since the L units will cancel out:

0.252 L * 0.33 mol/L = 0.08316

We have two significant figures here, so round 0.08316 to 0.083.

The answer is 0.083 moles.

Hope this helps!

Answer:

Explanation:i joule is equal to 0.238902957619 calories so 1251 joules is equal to 298.87 calories divided by 25.0 degrees centigrade is equal to 11.95 calories divided by the 35.2 gram sample weight to get the calories per gram per degree centigrade would come to 0.3396 calories/gram degree centigrade. Presumably this, if correct, could be used to obtain the metal in question by consulting a chart or table with specific heats of various metals because they should always be the same specific heat for each metal.

Answer:

The air in our atmosphere is composed of molecules of different gases. ... While the composition doesn't change much as you travel up through the lower layers of the atmosphere, what does change is the number of molecules. As you travel higher, the air molecules become less plentiful.

Explanation:

Answer:

Temperature variance at Redding > > Temperature variance beside at Eureka

Monthly temperatures at Redding are generally higher than the monthly temperatures beside the ocean at Eureka

Explanation:

Month             January

Eureka                Eureka          Redding      Redding

Average              Average          Average       Average

High                     Low                 High             Low

54°F                     41°F                   55°F              35°F

February

55°F                     43°F                  58°F              38°F

March

55°F                     43°F                   70°F          41°F

April

56°F                     45°F                   71°F          45°F

May

58°F                    48°F                    80°F         52°F

June

60°F                     51°F                     89°F         60°F

July

61°F                      52°F                      98°F         64°F

August

62°F                      53°F                      97°F         61°F

September

63°F                     51°F                         89°F          56°F

October

61°F                      49°F                        69°F         45°F

November

58°F                     45°F                        60°F         40°F

December

55°F                     42°F                        55°F           34°F

58                          46.92                  74.25            47.58        Mean

3.16                        4.25                     15.99            10.63         Standard Dev

9.97                       14.08                    255.84         112.992      Variance

63                           53                         98                64              Max  

54                           41                          55                34              Min

Based on the climate data that Sarah and Ruby collect, they can conclude that

From the data we have

From the data it is observed that the temperatures beside the ocean in Eureka are lesser than and more stable (vary less) than the temperatures in Redding, also the temperatures in Redding are much higher than the temperatures beside the ocean in Eureka.

Answer:

1. Limiting reactant.

2. Product.

3. Theoretical yield.

4. Reactants.

5. Actual yield

Explanation:

1. The limiting reactant. The limiting reactant is the reagent that is completely up in the reaction.

2. Product. Product is the result obtained From a reaction and the amount of product formed is determined by the limiting reactant

3. Theoretical yield. This is the result obtained from the stoichiometry calculations.

4. Reactant. Reactant are the starting material for a chemical reaction. The amount of the reactants determines the theoretical yield (products)

5. Actual yield. This is the result obtained from the experiment carried out in the laboratory.

Answer:

C3H6O

Explanation:

Data obtained from the question. This includes:

Carbon (C) = 0.62069 g

Hydrogen (H) = 0.103448 g

Oxygen (O) = 0.275862 g

The empirical formula can be obtained as follow:

Step 1:

Divide by their molar mass.

C = 0.62069 / 12 = 0.0517

H = 0.103448 / 1 = 0.103448

O = 0.275862 / 16 = 0.0172

Step 2:

Divide by the smallest number.

C = 0.0517 / 0.0172 = 3

H = 0.103448 / 0.0172 = 6

O = 0.0172 / 0.0172 = 1

Step 3:

Writing the empirical formula.

The empirical formula is C3H6O

Answer:

The empirical formula is C3H6O

Explanation:

Step 1: Data given

A sample of ethyl butyrate contains:

0.62069 g of carbon

0.103448 g of hydrogen

0.275862 g of oxygen

Atomic mass of carbon = 12.01 g/mol

Atomic mass of hydrogen = 1.01 g/mol

Atomic mass of oxygen = 16.0 g/mol

Step 2: Calculate moles

Moles = mass / molar mass

Moles carbon = 0.62069 grams / 12.01 g/mol

Moles carbon = 0.0517 moles

Moles hydrogen = 0.103448 grams / 1.01 g/mol

Moles hydrogen = 0.1024 moles

Moles oxygen = 0.275862 grams / 16.0 g/mol

Moles oxygen = 0.0172 moles

Step 3: Calculate the mol ratio

We divide by the smalllest amount of moles

C: 0.0517 moles / 0.0172 moles = 3

H: 0.1024 moles / 0.0172 moles = 6

O: 0.0172 moles / 0.0172 moles = 1

The empirical formula is C3H6O

Answer:

initial temperature of metal : 100

initial temperature of water : 22.4

final temp of both 27.1

Explanation: that one is for aluminum so i don’t know which metal you needed if for though

Answer:

Initial metal= 100

Initial water= 22.7

Final Both= 24.6

Explanation: THESE ARE FOR COPPER

Answer: Matter cannot be created or destroyed

Explanation: Balanced equations are set equations we cannot change one element or compound in the equation without changing the entire equation. So balanced equation show the conservation of mass because while other substances may be formed from the synthesis or decomposition of compounds new elements are never introduced and are not created out of thin air    :)

Answer:

Matter cannot be created or destroyed in chemical reactions. This is the law of conservation of mass. In every chemical reaction, the same mass of matter must end up in the products as started in the reactants. Balanced chemical equations show that mass is conserved in chemical reactions.

Answer:

= 25 %

Explanation:

Given that :

the genotype attributed to  trolls having one eye  = (EE, Ee);  that is homzygous dominant or heterozygote dominant for eye number

Likewise those that posses two eyes have (ee) ; that is homzygous recessive

Now; two heterozygous one eyed trolls are crossed ; we have :

Ee  × Ee

The punnet square for this cross looks like what we have below:

               E                e

E              EE              Ee

e              Ee               ee

From the above cross; we have:

1   EE    ---- (homozygous dominant ) indicating troll having one eye

2  Ee    ---- ( heterozygote dominant ) indicating troll having one eye

1  ee    ----- ( homozygous recessive ) indicating troll having two eyes

The genotypic ratio is 1:2:1

Thus; the expected genotype ratio of the two eyed offspring = [tex]\frac{1}{4}*100[/tex]

= 25 %  

Answer:

25% is the expected genotype ratio of the two-eyed offspring.

Explanation:

║ E ║ e ║

E║ EE ║ Ee ║

e ║ eE ║ ee ║

Answer:

Explanation:

Covalent catalysis is when a transient covalent bond is formed between substrate and residues such that so the enzyme nucleophilic group on an electrophilic moiety of the substrate is bound at the active site. Metal ion catalysis involves activating bound water through forming nucleophilic hydroxide ion.

Protonation or proton abstraction may be accomplished through the use of amino acids such as aspartate or Lysine in acid-base catalysis.

The term Catalysis is defined as the process of adding a catalyst to facilitate a reaction. During a chemical reaction, the bonds between the atoms in molecules are broken, rearranged, and rebuilt, recombining the atoms into new molecules.

Catalysis by covalent bonds the two-part catalytic process forms a covalent bond between enzyme and substrate (for example, chymotrypsin mechanism uses a nucleophilic functional group).

By changing the oxidation state, metal ion catalysis catalysts can participate in oxidation-reduction reactions.

Through ionic interactions, a Zn2+ cofactor may properly orient the substrate in the active site. May be involved in Fe2+ interactions.

All lowers activation energy or stabilizes the transition state or intermediate catalyst after the reaction occurs.

Thus, a proton is transferred between enzyme and substrate may use amino acids such as aspartate or Lysine for protonation or proton abstraction is called as acid-base catalysis.

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Your question is incomplete, most probably your question was

Enzymes use several types of catalytic mechanisms. Differentiate between acid-base catalysis, covalent catalysis, and metal ion catalysis.

Answer:

So Carbon-14 has eight neutrons and Carbon-12 has six neutrons. Hope it helps!

Answer:

A carbon-12 atom has 6 protons, 6 neutrons, and 6 electrons.

Answer:

they are characterized as a group by having 3 electrons in the outermost parts of their atomic structure. boron the lighter of these elements

Answer:

ΔH = -601.9 kJ/ mol Mg

Explanation:

Step 1: Data given

Mass of the solid magnesium sample = 0.2475 grams

The heat capacity of calorimeter = 3024 J/°C

The temperature increases by 2.027 °C

Step 2: Calculate the heat transfer

q = Ccal * ΔT

⇒with q = the heat transfer

⇒with Ccal = the heat capacity of calorimete 3024 J/°C

⇒ΔT = The temperature increases by 2.027 °C

q = 3024 J/°C * 2.027 °C

q = 6129.6 J

Since this is an exothermic reaction, ΔH will be negative

Step 3:Calculate the heat associated with the burning of Mg

Heat = -6129.6 J / 0.2475 grams Mg

Heat = 24766 J/grams = -24.77 kJ /grams Mg

Heat = -24.77 kJ/ grams * 24.3 g/mol

ΔH = -601.9 kJ/ mol Mg

The new volume of the soccer ball is 9 litres when temperature inside the can was 25°C and pressure remained constant.

Explanation:

Data given:

initial volume of the ball, V1 = 3.6 litres

temperature of the field, initial temperature, T1 = 10°C

temperature in the trash can, final temperature, T2 = 25 °C

pressure =constant throughout

volume of the ball when in trash can, final volume V2 =?

From the data given:

Charles' Law will be applied to know the volume of the ball in the can:

[tex]\frac{V1}{T1}=\frac{V2}{T2}[/tex]

putting the values in the equation after rearranging it:

V2 = [tex]\frac{V1T2}{T1}[/tex]

V2 = [tex]\frac{3.6 X 25}{10}[/tex]

V2 = 9 litres

The volume will be increased to 9 litres when ball will go inside the trash can.

Ideal gas law is valid only for ideal gas not for vanderwaal gas. Therefore the volume of N[tex]_2[/tex] will be made according to the equation is 2.64l.

Ideal gas equation is the mathematical expression that relates pressure volume and temperature. Ideal gas is a hypothetical gas. Vanderwaal gas can behave as ideal gas at low pressure and high temperature.

Mathematically,

PV=nRT

where,

P = pressure= 2.3atm

V= volume=?

n =number of moles=85.0/65.01

                               =1.30moles

T =temperature=348K

R = Gas constant = 0.0821 L.atm/K.mol

Substituting all the given values in the above equation, we get

2.3 × V=1.30× 0.0821 L.atm/K.mol × 348 K

V=1.76l

volume of nitrogen = 3/2× 1.76l=2.64l

Therefore the volume of N[tex]_2[/tex] will be made according to the equation is 2.64l.

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To calculate the volume of nitrogen gas produced from the decomposition of NaN3 at a given temperature and pressure, we must apply the stoichiometry from the balanced chemical equation and use the ideal gas law formula.

The student's question involves determining the volume of nitrogen gas (N2) produced from the decomposition of sodium azide (NaN3) under specified conditions of temperature (75 degrees Celsius) and pressure (2.3 atm). To solve this, one must use the ideal gas law, PV = nRT, where P is the pressure, V is the volume, n is the number of moles of gas, R is the ideal gas constant, and T is the temperature in Kelvin. The first step is to calculate the moles of N2 that can be produced from 85.0 grams of NaN3 using the stoichiometry of the given balanced equation.

Firstly, one needs to find the molar mass of NaN3 to convert grams to moles. Then, apply the stoichiometry from the balanced equation (2 mol NaN3 produces 3 mol N2). Finally, using the calculated number of moles of N2, apply the ideal gas law to find the volume of nitrogen gas at the given temperature and pressure.

Final answer:

Natural selection requires genetic variation within a population and environmental pressures that select for certain traits, leading to changes in the population's genetic makeup over generations.

Explanation:

For natural selection to take place in a population, two essential conditions must exist: genetic variation among individuals and environmental pressures that favor certain traits over others. Genetic variation ensures that there are differences in traits among individuals, which may be advantageous or not depending on the environmental context. These traits must have a genetic basis so that they can be inherited by the next generation.

Environmental pressures, such as climate change, predation, availability of resources, and competition, then determine which of these traits are beneficial, leading to the greater reproductive success of individuals with those traits, thus altering the genetic makeup of the population over time.

Answer:5000 s^-1

Explanation: Solution=

Using the formulae----> Kcat=Vmax/Et

where

Vmax is the maximum rate of the reaction when all the enzymes are saturated.

Vmax= 6.5 mmoles/s

Et=1.3 uM

1 mmole= 1000 umole

Changing to micromoles/sec, gives=

Vmax=   6.5 mmoles/s \times 1000= 6500 micromoles/s

Bringng back the equation,  

----->Kcat= Vmax/Et

= 6500/1.3

= 5000 /s

Therefore, our answer  is 5000 s^-1

Answer:

D) 18

Explanation:

Hello,

In this case, by considering the given rate law:

[tex]r=k[A]^2[B][/tex]

We also take into account that the concentration of A is tripled and the concentration of B is doubled, therefore, we have:

[tex]r=k[3*A]^2[2*B][/tex]

Which results in an increasing factor of:

[tex]3^2*2=9*2=18[/tex]

By considering only the tripling and the doubling, thus, the answer is D) 18.

Regards.

Answer:

Limiting factors are resources or other factors in the environment that can lower the population growth rate. Limiting factors include a low food supply and lack of space. Limiting factors can lower birth rates, increase death rates, or lead to emigration.

Explanation: