PLEASE HURRY!
What is the half-life of a 12 g sample of radioisotope that decayed to 6 g in 28
years?
A. 14 years
B. 7 years
C. 56 years
D. 28 years

Answers

Answer 1

Answer:

28 years

Explanation:

the information is literally in the question.

Answer 2
The answer is 28 years

Related Questions

Briefly explain why adding insulation to an attic helps reduce heating costs.

Answers

Answer:

Insulation reduces the exchange of heat through a surface such as a wall, attic, duct or roof. In a well-insulated home, less warm air escapes from the house during the winter, and less cool air escapes during the summer, reducing the amount of energy needed for heating and cooling

When your body is warmed by the sun during the winter, this process is said to be

a. exothermic.
b. endothermic.
c. isothermic.
d. none of the above

Answers

Answer:

B. Endothermic

Explanation:

Your body is absorbing the heat.

Which of the following correctly ranks the following bonds in order from most to least polar?

C-H, N-H, O-H, F-H


a)
O-H > F-H > N-H > C-H
b)
F-H > N-H > O-H > C-H
c)
C-H > N-H > O-H > F-H
d)
F-H > O-H > N-H > C-H

Answers

Answer:

O-H F-H N-Hy

Explanation:

C-H N-H O-H F-H

What does a vacuole mean

Answers


a small cavity or space in tissue, especially in nervous tissue as the result of disease.

Answer:

a space or vesicle within the cytoplasm of a cell, enclosed by a membrane and typically containing fluid.

or

a small cavity or space in tissue, especially in nervous tissue as the result of disease.

If the pH = 6.5, what is the [H+]? *
3.16 x 10-7
3.16 x 10-6
O
3.16 x 10-5

Answers

Answer:

Key Concepts

The hydrogen ion concentration in a solution, [H+], in mol L-1, can be calculated if the pH of the solution is known.

pH is defined as the negative logarithm (to base 10) of the hydrogen ion concentration in mol L-1 pH = -log10[H+] ...

[H+] in mol L-1 can be calculated using the equation (formula): [H+] = 10-pH

More items...

Explanation:

Answer:

[tex]pH = - log[H {}^{ + } ] \\ 6.5 = - log[H {}^{ + } ] \\ [H {}^{ + } ] = {10}^{ - 6.5} \\ [H {}^{ + } ] = 3.16 \times {10}^{ - 7} \: mol {dm}^{ - 3} [/tex]

Which sequence of steps describes the life cycle of a lake?
A. Runoff fills a depression - sediments build up - water becomes
increasingly shallow
B. Runoff fills a depression - sediments are eroded - water becomes deeper
C. Runoff fills a depression - sediments build up
- water rises continuously
D. Runoff fills a depression - sediments are eroded - water spreads over a wider area

Answers

Answer:

The actual sequence of steps which describe the life cycle of a lake is given below:

C. Runoff fills a depression - sediments build up

- water rises continuously

Explanation:

This is because, the water which builds up as a result of the runoff water accumulating on the depression helps towards building up. When it must have accumulated greatly, it ends up forming a lake.

1. In 1996 a meteor crashed into the Earth near Steelsville, Ontario. The resulting meteorite was found to contain 5,790 g of Molybdenum Chloride having a formula of Mo2Cl9. How many molecules of Mo2Cl9 are present in the 5,790 g meteor?

Answers

Answer:

6.38×10²¹ molecules

Explanation:

Formula for molybdenum chloride is:

Mo₂Cl₁₀

Molar mass is : (Molar mass for Mo) . 2 + (Molar mass for Cl) . 10

95.94  . 2 + 35.45  . 10 = 546.38 g/mol

We determine moles that are contained in 5.790 g of Mo₂Cl₁₀

5.790 g . 1 mol /546.38 g = 0.0106 moles

We count the molecules:  0.0106 mol . 6.02×10²³ molecules / mol =

6.38×10²¹ molecules

Remember that 6.02×10²³ is also called Avogadro's number (NA) which is the number of particles of anything, that are contained in 1 mol.

Which of the following best describes an electron transition?

A. An electron gains or loses energy and moves between continuous
energy levels.
B. An electron gains or loses charge and changes into a proton or a
neutron.
C. An electron gains or loses energy and moves between quantized
energy levels.
D. An atom gains or loses an electron and becomes an ion.

Answers

Answer:

A. An electron gains or loses energy and moves between continuous

energy levels.

what is the slope of the line segment

-3
-1/3
1/3
3​

Answers

Answer:

slope = 3

Explanation:

[tex]slope = \frac{3 - 0}{1 - 0} \\ = 3[/tex]

Joelle is a manager at a construction company, and she is interested in the chemistry behind the materials they use. She has begun studying the materials used to fill walls. She knows that to keep the temperature inside a room steady the material must be a thermal insulator, and she predicts that materials should not be acidic or else they would dissolve too easily in water.

Which of these is a molecular ingredient that could be used in a wall-filling material ?

C27H36N2O10
Na6Ba6
NeNa
HCl

Answers

Answer:

a

Explanation:

A molecular ingredient that could be used in a wall-filling material is C₂₇H₃₆N₂O₁₀, is not a good thermal insulator, hence option A is correct.

The big molecule C₂₇H₃₆N₂O₁₀ is a poor thermal insulator. Since NeNa is a relatively reactive chemical, it would probably dissolve in water far too quickly. The acidic molecule HCl would dissolve far too quickly in water.

Not a good thermal insulator is C₂₇H₃₆N₂O₁₀. It is a big molecule composed of a lot of hydrogen atoms. Since hydrogen atoms are excellent heat conductors, they would be ineffective in stopping heat from passing through a material used to fill a wall.

Thus, the option (A) C₂₇H₃₆N₂O₁₀ is correct.

Learn more about thermal insulator, here:

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how does evelyn hear music?​

Answers

Who even is Evelyn?

A carbon atom that is surrounded by four hydrogen atoms has a _____ molecular geometry. This geometry results from the arrangement of the _____ hybrid orbitals around the carbon atom. They are formed when the s-orbital and ______ -orbitals mix, or hybridize.

Answers

Answer:

Tetrahedral, sp3, p

Explanation:

C has 4 bonds and hence its tetrahedral shape with 109.5 degrees. since there are 4 bonds, it is sp3

Answer:

A carbon atom that is surrounded by four hydrogen atoms has a

✔ tetrahedral

molecular geometry.

This geometry results from the arrangement of the

✔ four sp3

hybrid orbitals around the carbon atom.

They are formed when the s-orbital and

✔ three p

-orbitals mix, or hybridize.

Explanation:

Please help I’ll give brainliest

Answers

Answer:

N2, O2 and Br2

Explanation:

N2, O2 and Br2 are formed of two atoms, so they are diatomic

This is a list of the seven diatomic elements. The seven diatomic elements are:

Hydrogen (H2)

Nitrogen (N2)

Oxygen (O2)

Fluorine (F2)

Chlorine (Cl2)

Iodine (I2)

Bromine (Br2)

an engineer chooses to use bamboo as a building material because it grows quickly and needs little space to grow. This is an example of?

Answers

Mark Brainliest please

Answer: This is an example of Green Design

Green design can be described as a method in which any building project is made by minimizing the harmful effects of construction on humans and environment. Green design is a sustainable design which is better for the economy too. In a green design, eco- friendly materials are used for construction works.
In the scenario discussed in the question, an engineer is using bamboo as a building material due to its eco- friendly features. Hence, it is an example of green design.

Answer:

A) This is an example of Green Design

Explanation:

Given the structural formula: This compound is classified as an

Answers

Answer:

A.) aldehyde is the answer

From the given structural formula, the compound is ethanamide and thus, belongs to the group of amides. Thus, the correct option is B.

Amide is a functional group of organic compounds having an acyl group (R-C=O) linked to amine group (-NR¹R² where R¹ and R² are hydrogen atoms or alkyl groups). The amide functional group is given as -CON= (not double bond with N, but two distinct single bonds).

Amides can be classified into the following types depending on the moiety attached to nitrogen other than the carbonyl carbon:

1. Primary amides - amide in which the nitrogen atoms is attached to two hydrogen atoms

2. Secondary amides - in which the nitrogen atom is attached to one hydrogen and one alkyl group.

3. Tertiary amides - in which the nitrogen atom is attached to two alkyl groups.

Learn more about amides in:

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What happens when an unstable nucleus undergoes radioactive decay?
A. Electrons change energy levels to balance the nucleus.
B. Energy is absorbed by the nucleus to make it more stable.
O C. Particles or electromagnetic radiation are emitted.
D. The nucleus increases in mass through radioactive decay.

Answers

i believe the answer is C. an unstable nucleus emits radiation and is transformed into the nucleus of one or more elements. i hope this helps!

Which question would most likely be studied by a biologist?
A.
How can a drug that treats cancer be synthesized?
B.
How can cancer-causing substances be regulated?
C.
How much ultraviolet radiation passes through the atmosphere?
D.
What causes cancer cells to grow uncontrollably?

Answers

Answer:

The correct answer would be - D. What causes cancer cells to grow uncontrollably?

Explanation:

A Biologist is a person that studies living organisms and the study of living organisms and their process called biology. Biology is a very vast field that involves many branches such as zoology, botany, biochemistry, immunology, biophysics, anatomy, ecology and many more.

So, given all are can be an example of the study biology wanted to do, however, the question most likely studied by a biologist would be What causes cancer cells to grow uncontrollably as it deals with an organism and their biological process.

Which of the following could possibly be true about a strong acid? (Check all that apply:).
It will completely dissociate (break apart) when dissolved in water.
It could have a pH of 6
It could have a pH of 13
Only a few of the acid molecules will dissociate (break apart).
It could have a pH of 2.
It could have a pH of 9

Answers

Answer:

it could have a pH of 2 it will completely dissociate when dissolved in water

If 15.0 mL of phosphoric acid completely neutralizes 38.5 mL of 0.150 mol/L calcium hydroxide, what is the concentration of the phosphoric acid?

Answers

Answer:

Let me give it a try.

H3PO4 + Ca(OH)2 = Ca3(PO4)2 + H2O

Balancing this reaction

2H3PO4 + 3Ca(OH)2 == Ca3(PO4)2 + 6H2O.

Moles= Molarity x Volume

Volume = 38.5ml = 0.0385L

Moles of Ca hydroxide = 0.150m/L x 0.0385L

(Notice the units canceling out...leaving moles).

=0.005775moles of Ca(OH)2.

From balanced reaction...

3moles of Ca(OH)2 completely reacts with 2moles of H3PO4

0.005775moles of Ca(OH)2 would completely react with....

= 0.005775 x 2/(3)

=0.00385moles of H3PO4.

Now we're looking for its Concentration in Mol/L

Molarity=Moles of solute/Volume of solution(in L)

Volume of solution assuming no other additions to the reaction = 15ml + 38.5ml =53.5ml =0.0535L

Molarity = 0.00385/0.0535

=0.072Mol/L.

If this is wrong

then Simply Try The formula for Mixing of solutions

C1V1 = C2V2

0.15 x 38.5 = C2 x (15+38.5)

C2 = 0.11M/L.

An example of a product made from a synthetic material is
Question 5 options:

A)

a PET plastic water bottle.

B)

knitted wool socks.

C)

a cotton t-shirt.

D)

a pine 2×4 board.

Answers

Hi there! A simple answer and explanation is below :)

Answer:

A) PET plastic water bottle

Explanation:

Plastic goes through a manufacturing process before being used to make bottles for liquids like milk, soda, motor oil, and shampoo, as well as dry items like pharmaceuticals and nutritional supplements. Plastic is made up of a variety of organic polymers, including polyethylene and ethylene, in its unprocessed condition. In a soft state, plastic can be molded into the desired shape and then cast into a solid stat

What is the pH of a solution?
O A. A measure of the strength of the acid
B. A measure of the buffering ability of the solution
O c. A measure of the hydrogen gas concentration
O D. A measure of the acidity of the solution

Answers

Answer:

D. A measure of the acidity of the solution

Explanation:

pH is a measure of how acidic or basic a solution is, and is measured on a scale from 0-14, where 7 is neutral, anything less than 7 is acidic, and anything more than 7 is basic.

show using dots to illustrate high population density and low population density in the boxes provided in answer to guide questions ​

Answers

Answer:

Just add a plenty of dots in the first one and very few dots in the second one

An area with high population density will have many dots while areas will low population density will have few dots when using dots to illustrate population density.

What is population density?

Population density is the ratio of the total number of organisms found in a given area to the total of the area of that place or habitat.

Population density = total number of organisms/total area

An area with high population density indicates that more organised ate found per unit area than an area with low population density.

Therefore, using dots to illustrate population density, an area with high population density will have plenty dots while areas will low population density will have few dots scattered over.

Learn more about population density at: https://brainly.com/question/13902749

Chemistry 1 question please help!! 10 points

Answers

Answer:

3

Explanation:

its the 3 one it is

What is the delta H when 72.0 grams H2O condenses at 100.00C?

Here are some constants that you MAY need.

specific heats heat of fusion heat of vaporization

H2O(s) = 2.1 J/g0C 6.01 kJ/mole 40.7 kJ/mole

H2O(L) = 4.18 J/g0C

H2O(g) = 1.7 J/g0C



2930 kJ


163 kJ


-163 kJ


-2930 kJ

Answers

Answer: The value of [tex]\Delta H[/tex] is -163 kJZ

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)

We are given:

Given mass of water = 72.0 g

Molar mass of water = 18 g/mol

Putting values in equation 1, we get:

[tex]\text{Moles of water}=\frac{72.0g}{18g/mol}\\\\\text{Moles of water}=4mol[/tex]

Calculating the heat released for the condensation process:

[tex]\Delta H=n\times \Delta H_{(vap)}[/tex] ......(2)

where,

[tex]\Delta H[/tex] = amount of heat released

n = number of moles of water = 4 moles

[tex]\Delta H_{(vap)}[/tex] = specific heat of vaporization = -40.7 kJ/mol

Negative sign represents the amount of heat released.

Putting values in equation 2:

[tex]\Delta H=4mol\times (-40.7kJ/mol)=-163kJ[/tex]

Hence, the value of [tex]\Delta H[/tex] is -163 kJ

Use mathematics to prove that the 5.50 grams of salicylic acid (C7H6O3) used in this experiment is equal to 0.04 mol.

Answers

Answer:

Please find the answer to the question below

Explanation:

In chemistry, the following mathematical formula is used to calculate the number of moles contained by a substance:

mole = mass of substance (g)/molar mass of substance (g/mol)

Molar mass of salicylic acid (C7H6O3) = 12(7) + 1(6) + 16(3)

= 84 + 6 + 48

= 138g/mol

Mass = 5.50grams

mole = 5.5/138

mole = 0.039

Approximately, the number of moles of 5.5grams of salicylic acid is 0.04moles. This is in accordance with the mole value (0.04) given in this question.

Por qué razón se fomenta la inmigración Europea?​

Answers

Hola aquí va la respuesta!

Se fomentó la inmigración europea porque la economía no era buena y vinieron a Paraguay para mejorar su situación.

Hola aquí va la respuesta!

Se fomentó la inmigración europea porque la economía no era buena y vinieron a Paraguay para mejorar su situación.

A. 2 pts: In terms of conservation of mass, what were the results of each experiment (which one conserved mass and which one did not)?
B. 4 pts: PROVIDE a SPECIFIC explanation for "why" the results in both videos were different.
. 2 pts: Discuss differences in the experimental steps between the two videos (for example what was done in video one that was not done in
video two, why would this make a difference in conserving mass?)
• 2 pts: Look at both chemical equations (below for convenience), what difference in the type of products would have contributed to the
differences in why one conserved mass and one did not?
REACTION 1: Pb(NO3)2 (aq) + 2K1 (aq) --> 2KNO3 (aq) +Pölz (s)
• REACTION 2: NaHCO3(s) + CH3COOH(aq) → CO2(g) + H2Om + CH3COONa(aq)

Answers

Answer:

dftdffdgxrdfdrdxxxxdddddddddddddeeertdffddy

A + 2 B + 4 C → products is known to be second order in A, first order in B and independent of the concentration of C. What is the value of the rate constant for this reaction if its rate is 0.783 M · s−1 when [A] = 5.00 M, [B] = 7.00 M, and [C] = 3.00 M? −2 −1 Answerinunitsof M ·s .

Answers

Answer:

4.47 × 10⁻³ M⁻² s⁻¹

Explanation:

Let's consider the following generic equation.

A + 2 B + 4 C → products

This reaction is known to be second order in A, first order in B and independent of the concentration of C (zero order in C). The rate law is:

rate = k × [A]² × [B] × [C]⁰

rate = k × [A]² × [B]

where k is the rate constant

When the rate is 0.783 M/s, [A] = 5.00 M, [B] = 7.00 M, and [C] = 3.00 M, the rate constant is:

k = rate / [A]² × [B]

k = 0.783 M/s / (5.00)² × (7.00) = 4.47 × 10⁻³ M⁻² s⁻¹

Use the equation below to answer the following question
2NaHCO3(aq) + Ca(H2PO4)2 (aq) → Na2HPO4 (aq) + CaHPO4 (aq) + 2002 (8) + 2H20 (0)
The theoretical yield of CHPO, is 10 g. If 8 g of CaHPO4 are produced from the reaction shown above, what is the percent yield of CHPO ?

Answers

Answer:

Percent Yield = 80%

Explanation:

Percent yield of a reaction is defined as one hundred times the ratio between the actual yield and the theoretical yield. That is:

Percent yield = Actual Yield / Theoretical Yield * 100

Where theoretical yield of CaHPO4 is 10g and actual yield is 8g

Replacing:

Percent yield = 8g / 10g * 100

Percent Yield = 80%

The metric system is also known as the

Answers

Answer:

THE answer is all of above

Explanation:

The metric system, also known as the Système international d'unités (SI), was developed in the late 1700s to standardize units of measurement in Europe. The metric system is the primary system of measurement used through much of the world and in science.
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if humans began hunting and driving the great barracuda to extinction how would this affect the ecosystem (answer should discuss biodiversity, food webs, and food chains) does the great pyramid of giza fit the golden ratio? why or why not? Kent Fuller is in the 34 percent tax bracket. A nontaxable employee benefit with a value of $2,300 would have a tax-equivalent value of:____.a. $345.b. $1,523.c. $1,948.d. $1,155.e. 1,500. hted by f(x) = 44.03The type of function represented I would really appreciate if someone could answer this:) Simplify the fraction to lowest terms.56/182 Which of the following could occur as the result of runoff of high nitrogen fertilizers from farmlands near a lake?O an increase in algae growth resulting in low oxygen levels in the lakeO a decrease in mineral storage reducing carbon levels of the lakeO a decrease in pollution in lower ozone levels in the lake areaO an increase in deforestation reducing animal populations in the lake area Triangle ABC IS dilated using the origin as the center of dllation to create triangle A'B'C'. What rule best represents the dilation applied to triangle ABC to Plyometrics can help a person maintain cardiorespiratory fitness true or false Face to face communication is better than other types of communication, such as letters, emails, or telephone calls. What is your opinion?write one opinion paragraph In an online shopping application, the primary case type PurchaseOrder has two child case types: Payment and Packaging. In processing PurchaseOrder case PO-11, Payment case Pay-37 and Packaging case Pac-56 are created. Which statement about the processing of PO-11, Pay-37, and Pac-56 is correct?A. PO-11 has to be resolved before either Pay-37 and Pac-56 is resolved.B. Pac-56 has to be resolved before Pay-37 is resolved.C. Both Pay-37 and Pac-56 have to be resolved before PO-11 can be resolved.D. PO-11 can be resolved when either Pay-37 or Pac-56 is resolved. In what ways did family relationships affect enslaved people? (You can think of ways therelationships were helpful and also ways the relationships were exploited by enslavers.) how accurate as indicators of electoral success are informal requirements based on political party, electoral experience, race, gender, religion, education, and wealth? a relative density bottle has a mass of 29.2 g when empty its mass is 116.2 g when it is full of liquid or diesel and when full of water it's mass is 129.2 g calculate the relative density of diesel hey dale plzzzz helppp I neeed the answer plssss A sports magazine prints 12 issues per year, and a technology magazine prints 10 issues per year. The total number of pages in all the issues of the sports magazine for one year is 32 more than the total number of pages in all the issues of the technology magazine for one year. Each issue of the sports magazine has 18 fewer pages than each issue of the technology magazine. Which system of equations can be used to find s, the number of pages in each issue of the sports magazine, and t, the number of pages in each issue of the technology magazine?A. t = s - 1810t = 12s + 32B. s = t - 1812s = 10t + 32C. s = t - 1810s = 12t + 32D. t = s - 1812t = 10s + 32 PLEASE HELP ITS TIMED LITTERALY IM BEGGING :(( 32 points WITH BRAINLIEST!! Please help Ill give brainliest ima give branliest if you answer this correctly