How many days will it take for 80 grams of Iodine-131 to decay to 5 grams?

Answer:

a. Approximately [tex]1.3\; \rm mL[/tex].

b. Approximately [tex]7.2\; \rm mL[/tex].

Explanation:

The unit of concentration "[tex]\rm M[/tex]" is equivalent to "[tex]\rm mol \cdot L^{-1}[/tex]", which means "moles per liter."

However, the volume of both solutions were given in mililiters [tex]\rm mL[/tex]. Convert these volumes to liters:

[tex]\displaystyle 45\; \rm mL = 45\; \rm mL \times \frac{1\; \rm L}{1000\; \rm mL} = 0.045\; \rm L[/tex].

[tex]\displaystyle 330\; \rm mL = 330\; \rm mL \times \frac{1\; \rm L}{1000\; \rm mL} = 0.330\; \rm L[/tex].

In a solution of volume [tex]V[/tex] where the concentration of a solute is [tex]c[/tex], there would be [tex]c \cdot V[/tex] (moles of) formula units of this solute.

Calculate the number of moles of [tex]\rm NaCl[/tex] formula units in each of the two solutions:

Solution in a.:

[tex]n = c \cdot V = 0.045\; \rm L \times 0.10\; \rm mol \cdot L^{-1} = 0.0045\; \rm mol[/tex].

Solution in b.:

[tex]n = c \cdot V = 0.330\; \rm L \times 0.074\; \rm mol \cdot L^{-1} = 0.02442\; \rm mol[/tex].

What volume of that [tex]3.4\; \rm M[/tex] (same as [tex]3.4 \; \rm mol \cdot L^{-1}[/tex]) [tex]\rm NaCl[/tex] solution would contain that many

For the solution in a.:

[tex]\displaystyle V = \frac{n}{c} = \frac{0.0045\; \rm mol}{3.4\; \rm mol \cdot L^{-1}} \approx 0.0013\; \rm L[/tex].

Convert the unit of that volume to milliliters:

[tex]\displaystyle 0.0013\; \rm L = 0.0013\; \rm L \times \frac{1000\; \rm mL}{1\; \rm L} = 1.3\; \rm mL[/tex].

Similarly, for the solution in b.:

[tex]\displaystyle V = \frac{n}{c} = \frac{0.02442\; \rm mol}{3.4\; \rm mol \cdot L^{-1}} \approx 0.0072\; \rm L[/tex].

Convert the unit of that volume to milliliters:

[tex]\displaystyle 0.0072\; \rm L = 0.0072\; \rm L \times \frac{1000\; \rm mL}{1\; \rm L} = 7.2\; \rm mL[/tex].

Answer:

3.01 x 10²³ molecules

Explanation:

Given parameters:

Number of moles of oxygen atoms  = 6.17moles

Unknown:

Number of molecule of tin(IV) nitrate  = ?

Solution:

To solve this problem, let us write the formula of tin (IV) nitrate;

              N₄O₁₂Sn

Now,

       12 moles of Oxygen can be found in 1 mole of  N₄O₁₂Sn

      6.17 moles of oxygen will be found in [tex]\frac{6.17}{12}[/tex]   = 0.5mole of  N₄O₁₂Sn

So;

       1 mole of a substance contains 6.02 x 10²³ molecules

  0.5 mole of N₄O₁₂Sn will contain 0.5 x 6.02 x 10²³ = 3.01 x 10²³ molecules

Answer:

here are what i have so far, im doing this right now

Explanation:

Plate Tectonics Lab Report

Instructions: In the Plate Tectonic lab you will investigate the interactions between continental and oceanic plates at convergent, divergent, and transform boundaries around the globe. Record your observations in the lab report below. Y

Objective(s):  

To look at interactions between continental and oceanic plates, etc.  

Hypothesis:

In this section, please include the if/then statements you developed during your lab activity for each location on the map. These statements reflect your predicted outcomes for the experiment.

Location One: Select three events that you predict will be observed. If I explore two continental plates at a convergent boundary, then I will observe:

• earthquakes  

• mountains

• volcanoes

Location Two: Select three events that you predict will be observed. If explore two continental plates at a divergent boundary, then I will observe:  

• ocean formation  

• volcanoes

• seafloor spreading

you will submit your completed report

ps; you might want to change up the objective.

A geological event is a brief, spatially diverse, dynamic and ongoing occurrence in the history of the Earth.

A geological event is a brief, spatially diverse, dynamic (diachronous), and ongoing occurrence in the history of the Earth that aids in the modification of the Earth system and the production of geological strata. The concept of event stratigraphy initially came up as a way to identify, analyse, and correlate how significant physical and biological events have affected the overall stratigraphical record.

Israel's Dead Sea basin Holocene sediments contain seismic activity. This can be considered a record of a geological event, an earthquake, that altered the strata. Geological events can occur over timescales of order of magnitude, from just a few seconds through millions of years, as well as on a variety of spatial scales, from the local to the globe.

1. Volcanoes and minor earthquakes

2. Volcanoes, earthquakes and fold mountains.

3. Earthquakes and fold mountains.

4. Magma from volcanoes is filled with nutrients that makes land fertile.

Therefore, a geological event is a brief, spatially diverse, dynamic and ongoing occurrence in the history of the Earth.

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Answer:

0.0035M

Explanation:

Given parameters

Volume of HCl  = 100mL  = 0.1L

Volume of LiOH = 46.9mL  = 0.0469L

Molarity of LiOH = 0.75M

Unknown:

Concentration of hydrochloric acid = ?

Solution:

The reaction equation is given as;

         HCl   +  LiOH →   LiCl  + H₂O

Let us find the number of moles of the given specie which is LiOH;

   Number of moles  = molarity x volume;

    Number of moles of LiOH = 0.75 x0.0469  = 0.035moles

From the balanced reaction equation;

        1 mole of LiOH combines with 1 mole of HCl

     0.035mole of LiOH will require 0.035mole of HCl

Concentration of HCl = [tex]\frac{number of moles of HCl}{volume of HCl}[/tex]  

 Concentration of HCl  = [tex]\frac{0.035}{0.1}[/tex]   = 0.0035M

Answer:The formula of magnesium chloride is MgCl2 . The molar mass of MgCl2 is (24.30 + 2 × 35.45) g/mol=95.20 g/mol .

Explanation:

Answer: c. Water

Explanation:

Heat capacity can be defined as the physical property of the matter. It is the amount of heat which is required to produce a unit change in the temperature of the material.

Water requires more amount of energy per gram of the liquid to change its temperature as compare to any other liquid like ethanol and oil. Ethanol is a volatile liquid so it will require less heat to boil but heat capacity of oil will be more than the oil. The heat capacity of water will be the highest, and it will require more heat.

Answer:

Ne

Explanation:

It has the lowest density.

Neon has the lowest density since it has the smallest atomic size and the lowest atomic number.

The atomic density of an element refers to the number of atoms contained in an element per unit volume.

The size of an atom has an effect on atomic density. The size of an atom increases from left to right across the period and top to bottom down the group.

As such, on the periodic table, as we move from top to bottom down the group, the density of an atom increases.

The atomic element of the given elements are:

Therefore, we can conclude that Neon (Ne) will have the lowest density since it has the smallest atomic size and the lowest atomic number.

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Answer:

The wavelength of the energy that needs to be absorbed  = 52.36 nm

Explanation:

For this study;

Let consider the Rydgberg equation from Bohr's theory of atomic model:

i.e.

[tex]\dfrac{1}{\lambda} = R_H (Z^*)^2( \dfrac{1}{n_1^2}-\dfrac{1}{n_2^2})[/tex]

where

Z* = effective nuclear charge of atom = Z - σ = 6

n₁ = lower orbit = 3

n₂ = higher orbit = 4

[tex]R_H[/tex] = Rydyberg constant = 1.09 × 10⁷ m⁻¹

λ = wave length of the light absorbed

∴

[tex]\dfrac{1}{\lambda} = 1.09 \times 10^7}(6)^2( \dfrac{1}{3^2}-\dfrac{1}{4^2})[/tex]

[tex]\dfrac{1}{\lambda} = 1.09 \times 10^7}(36)( \dfrac{1}{9}-\dfrac{1}{16})[/tex]

[tex]\dfrac{1}{\lambda} = 392400000\times0.0486111111[/tex]

[tex]\dfrac{1}{\lambda} =19075000[/tex]

[tex]\lambda = \dfrac{1}{19075000}[/tex]

[tex]\lambda = \dfrac{1}{1.91\times 10^7 \ m^{-1}}[/tex]

[tex]\lambda = 5.236 \times 10^{-8} m[/tex]

[tex]\lambda = 52.36 \times 10^{-9} m[/tex]

[tex]\lambda = 52.36\ n m[/tex]

Therefore, the wavelength of the energy that needs to be absorbed  = 52.36 nm

Answer:

Zamir walked

27

meters and Talia walked

19

meters.

Explanation:

27 and 19

Answer:

zamir:27  Talia:19

Explanation:

i got it right on my test :)

.

.

[tex]

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b competition .

hope it helps u

Answer:

0.184 M

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

HCl + NaOH —> NaCl + H2O

From the balanced equation above, the following data were obtained:

Mole ratio of the acid, HCl (nA) = 1

Mole ratio of the base, NaOH (nB) = 1

Next, the data obtained from the question. This includes:

Volume of the base, NaOH (Vb) = 31.7 mL Molarity of the base, NaOH (Mb) = 0.145 M

Volume of the acid, HCl (Va) = 25.0 mL

Molarity of the acid, HCl (Ma) =?

Finally, we shall determine the molarity of the acid (HCl) as shown below:

MaVa /MbVb = nA/nB

Ma × 25 / 0.145 × 31.7 = 1

Cross multiply

Ma × 25 = 0.145 × 31.7

Ma × 25 = 4.5965

Divide both side by 25

Ma = 4.5965 / 25

Ma = 0.184 M

Therefore, the molarity of the acid (HCl) is 0.184 M

The concentrations : 0.15 M

pH=11.21

The ionization of ammonia in water :

NH₃+H₂O⇒NH₄OH

NH₃+H₂O⇒NH₄⁺ + OH⁻

The concentrations of all species present in the solution = 0.15 M

Kb=1.8 x 10⁻⁵

M=0.15

[tex]\tt [OH^-]=\sqrt{Kb.M}\\\\(OH^-]=\sqrt{1.8\times 10^{-5}\times 0.15}\\\\(OH^-]=\sqrt{2.7\times 10^{-6}}=1.64\times 10^{-3}[/tex]

[tex]\tt pOH=-log[OH^-]\\\\pOH=3-log~1.64=2.79\\\\pH=14-2.79=11.21[/tex]

I'll see what I can do here...

1) Nonmetal

2) Calcium (Ca), chemical element, one of the alkaline-earth metals of Group 2 (IIa) of the periodic table.

3) Hafnium

4) 204.3833 u

5) Not sure what you're asking, but oble gas, any of the seven chemical elements that make up Group 18 (VIIIa) of the periodic table. The elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og)

6) The metalloids; boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), polonium (Po) and astatine (At)

7) The Actinide series contains elements with atomic numbers 89 to 103 and is the third group in the periodic table.

8) 33

9) 88

10) 30

Hope this helps!

Answer:

The final temperature of the water when measuring the food sample is: The temperature of the water when the food sample has finished burning completely.

Explanation:

When measuring the food sample in energy and specific heat lab, it is pertinent to note that there is an initial temperature and even while still burning, the temperature gradually increases. But since we are dealing with final, temperature, what we need is basically the final temperature of the water when the food has finished burning. This is so because that's the final temperature of the water as once the food sample has finished burning and you turn off the heat source, the temperature will start to gradually reduce from then on.

Answer:

Explanation:

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]

From the question we have

[tex]n = \frac{4.5 \times {10}^{24} }{6.02 \times {10}^{23} } \\ = 7.475083056...[/tex]

We have the final answer as

Hope this helps you

Answer: Potassium and fluorine

Explanation:

The two rows form bonds the easiest

Answer: #1

Explanation:

Answer:

232.4 grams of KI solution

Explanation:

Well, we first start off by using like units. The concentration (M) of KI can be rewritten as Moles/ Liter, which makes the solution rewritten as 2.80 Moles/ 1 L.

We also know that 1000 Milliliters are equal to 1 Liter, therefore we can rewrite the 500 Milliliters as 0.500 Liters from doing a conversion (500 mL x  (1 L/1000 mL)= 0.500 L).

From here we multiply the concentration by the number of liters to leave us with moles ((2.80 Moles/ 1 L)  x  0.500 L= 1.4 Moles).

Now, we must find the molar mass of the KI solution, this can be done either by googleing it or adding the molar mass of each element in the compound via the periodic table. In this case, the molar mass for the Potassium in the compound is 39 g/mol while the Iodine is 127 g/mol. Those add to 166 g/mol, and now we can convert to grams from moles.

Now, we multiply the moles by the molar mass to cancel out the moles and leave us with grams. (1.4 mol x (166 g/mol)= 232.4 grams).

I hoped this helps and good luck with your semester in Chemistry!

Answer:

is used

Explanation:

Answer:

6.022×10²³ atoms of K

Explanation:

Given data:

Mass of KClO₃ = 122.5 g

Number of atoms of K = ?

Solution:

First of all we will calculate the number of moles of KClO₃ .

Number of moles = mass/molar mass

Number of moles = 122.5 g/ 122.5 g/mol

Number of moles = 1 mol

One mole of KClO₃ have 1 mole of K atoms.

Number of atoms of K:

1 mole = 6.022×10²³ atoms of K

Thus in 122.5 g of KClO₃  6.022×10²³ atoms of K are present.

Answer:

The third one

Explanation:

Answer:

Explanation:

in a combustion of ethane 2 moles of ethane react with 7 moles of O2

now no of moles in 54 gram of O2=mass/ molar mass

moles =54/32=1.7 moles

if 7 moles of O2 required 2 moles of ethane then 1.7 mole required=?

7 moles of O2=2 moles of C2H6

1.7 moles of O2=1.7*2/7=0.5 moles of C2H6

0.5 moles of C2H6 contain how much grams=?

mass= moles*molar mass=0.5*30=15

Answer:

organic molecules made up of carbon and hydrogen elements joined together in long groups called hydrocarbons. The arrangement of these hydrocarbon chains, and their interaction with each other, determines fat type.

The study of chemicals and their bond is called chemistry.

The correct answer is lipid.

Those molecules which are present in the cell more than the amount of 800 daltons are called macromolecules.

According to the question, the correct answer is lipid because in lipid all the molecules are made up of a long chain of carbon and hydrogen join together.

For example, palmitic is made up of 16 carbon compounds.

Hence, the correct answer is lipid.

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Answer:

100 mL of Na2CO3

Explanation:

We'll begin by calculating the number of mole in 1 g of CaCO3. This can be obtained as follow:

Mass of CaCO3 = 1 g

Molar mass of CaCO3 = 100.09 g/mol

Mole of CaCO3 =?

Mole = mass /Molar mass

Mole of CaCO3 = 1/100.09

Mole of CaCO3 = 0.01 mole

Next, we shall determine the number of mole of Na2CO3 needed to produce 0.01 mole of CaCO3.

This is illustrated below:

Na2CO3 + CaCl2 —> 2NaCl + CaCO3

From the balanced equation above,

1 mole of Na2CO3 reacted to produce 1 mole of CaCO3.

Therefore, 0.01 mole of Na2CO3 will also react to produce 0.01 mole of CaCO3.

Next, we shall determine the volume of Na2CO3 needed for the reaction as illustrated below:

Mole of Na2CO3 = 0.01 mole

Molarity of Na2CO3 = 0.1 M

Volume of Na2CO3 solution needed =?

Molarity = mole /Volume

0.1 = 0.01 / volume of Na2CO3

Cross multiply

0.1 × volume of Na2CO3 = 0.01

Divide both side by 0.1

Volume of Na2CO3 = 0.01 / 0.1

Volume of Na2CO3 = 0.1 L

Finally, we shall convert 0.1 L to millilitres (mL). This can be obtained as follow:

1 L = 1000 mL

Therefore,

0.1 L = 0.1 L × 1000 mL / 1 L

0.1 L = 100 mL

Thus, 0.1 L is equivalent to 100 mL.

Therefore, 100 mL of Na2CO3 is needed for the reaction.

The volume of sodium carbonate used in the given reaction is 0.1 liter or 100mL.

Volume of the solution will be calculated by using the molarity as:

M = n/V, where

n is the moles of solute and this can be calculated as:

n = W/M , where

W = given or required mass

M = molar mass

Given chemical reaction is:
Na₂CO₃ + CaCl₂ → CaCO₃ + 2NaCl

Moles of 1g of CaCO₃ = 1g/100g/mole = 0.01 moles

From the stoichiometry of the reaction, it is clear that same moles of CaCO₃ produced by same moles of used Na₂CO₃.

0.01 moles of CaCO₃ = produced by 0.01 moles of Na₂CO₃

Now we calculate the volume of 0.01 moles and 0.100M of Na₂CO₃ as:

V = n/M

V= 0.01/0.100 = 0.1L or 100mL

Hence 0.1 L is the required volume.

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Answer:

[tex]m_{CO_2}=3.709gCO_2 \\\\m_{H_2O}=1.898gH_2O[/tex]

Explanation:

Hello.

In this case, since the molecular formula of the given alcohol is C₄H₁₀O (molar mass = 74.14 g/mol), we can write its combustion reaction as shown below:

[tex]C_4H_1_0O+6O_2\rightarrow 4CO_2+5H_2O[/tex]

Thus, since there is a 1:4 mole ratio with carbon dioxide (molar mass = 44..01 g/mol) and a 1:5 mole ratio with water (molar mass = 18.02 g/mol), we can compute the obtained masses as shown below:

[tex]m_{CO_2}=1.562gC_4H_1_0O*\frac{1mol}{74.14gC_4H_1_0O} *\frac{4molCO_2}{1molC_4H_1_0O} *\frac{44.01gCO_2}{1molCO_2}=3.709gCO_2 \\\\m_{H_2O}=1.562gC_4H_1_0O*\frac{1mol}{74.14gC_4H_1_0O} *\frac{5molH_2O}{1molC_4H_1_0O} *\frac{18.02gH_2O}{1molH_2O}=1.898gH_2O[/tex]

Best regards!

Answer:

False. because weathering happens first, then erosion takes place.

Explanation:

Weathering is the breaking down or dissolving of rocks and minerals on Earths surface. Once a rock has been broken down, a process called erosion transports the bits of rock and minerals away. Water, acids, salt, plants, animals, and changes in temperature are all agents of weathering and erosion.

Weathering and erosion are different names for the same process is false.

Erosion is defined as the geological process wherein earthen components are eroded and moved by elements like wind or water. Soil erosion primarily occurs when dirt is exposed to strong winds, copious rain, and moving water. Some human endeavors, especially farming and land clearance, increase the susceptibility of soil to erosion.

Erosion occurs when these natural forces shift the smaller rock fragments. Weathering is what happens when a rock is altered or damaged but remains in its current location. Erosion is the process through which the fragments of weathered rock are removed. The processes that reduce rocks to little particles are erosion and weathering.

Thus, weathering and erosion are different names for the same process is false.

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Hydrogen can only form single covalent bonds when forming molecular compounds. Therefore, option B is correct.

A covalent bond is a type of chemical bond formed between two or more atoms in which electrons are shared between them. Covalent bonds usually occur between nonmetal atoms and are formed by the sharing of valence electrons.

Hydrogen can only form a single covalent bond because it has only one valence electron and needs one more electron to complete its valence shell, making it stable.

Nitrogen can form triple covalent bonds, carbon can form multiple covalent bonds, and oxygen can form double covalent bonds in molecular compounds.

Thus, option B is correct.

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Answer:

1.99 x 10⁻¹⁸J

Explanation:

Given parameters:

Frequency of the wave  = 3 x 10¹⁵Hz

Unknown:

Energy of the photon  = ?

Solution:

To solve this problem, we use the expression below;

     E  = hf

Where E is the energy, h is the Planck's constant and f is the frequency

Now insert the parameters and solve for E;

     E  = 6.63 x 10⁻³⁴ x 3 x 10¹⁵ = 19.9 x 10⁻¹⁹J or 1.99 x 10⁻¹⁸J

Answer:

Speed of light

Explanation:

The value 3.0 x 10⁸m/s is taken as the speed of light.

It is a constant.