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From the calculations and the principles of radioactivity, the age of the parent isotope is 144 years

The term radioactivity has to do with the spontaneous decay of a substance.

We know that we have about 25% parent isotope still remaining hence;

[tex]0.693/t1/2 =2.303/t log No/N\\When N =0.25 No and t1/2 = 72 years\\0.693/72 =2.303/t log No/0.25No\\0.0096 = 2.303/t *0.60206\\0.0096 = 1.3865/t\\t = 1.3865/0.0096\\t =144 years[/tex]

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Answer:

A. 144 years old

Explanation:

Answer:

2

Explanation:

Answer:

[tex]\boxed {\boxed {\sf 12.5 \ mL \ NaOH}}[/tex]

Explanation:

In a neutralization reaction, an acid and base react to form salt and water. The hydrogen ions (H+) and hydroxide ions (OH-) combine to form water, while the other spectator ions bond to make salt.

For this reaction, the acid is HCl (hydrochloric acid) and NaOH (sodium hydroxide).

The H (from HCl) and OH (from NaOH) combine to make water (HOH or H₂O). The other ions, Cl and Na combine to form NaCl or sodium chloride. Let's write the neutralization reaction.

[tex]HCl _{(aq)}+NaOH _{(aq)} \rightarrow NaCl _{(aq)} + H_2O _{(l)}[/tex]

Now let's perform the calculation. We should use the titration equation or:

[tex]M_AV_A= M_BV_B[/tex]

where M is the molarity of the acid or base and V is the volume.

We know there are 25 milliliters of 1 molar HCl (acid) and an unknown volume of 2 molar NaOH (base).

[tex]\bullet M_A= 1 \ M \\\bullet V_A= 25 \ mL \\\bullet M_B= 2 \ M[/tex]

Substitute the known values into the formula.

[tex]1 \ M * 25 \ mL = 2 \ M * V_B[/tex]

Since we are solving for the volume of the base, we must isolate the variabel. it is being multiplied by 2 M and the inverse of multiplication is division. Divide both sides by 2 M.

[tex]\frac { 1 \ M * 25 \ mL}{2 \ M }=\frac{2 \ M * V_B}{2 \ M}[/tex]

[tex]\frac { 1 \ M * 25 \ mL}{2 \ M }= V_B[/tex]

The units of M cancel.

[tex]\frac { 1 * 25 \ mL}{2 }=V_B[/tex]

[tex]\frac {25}{2} \ mL= V_B[/tex]

[tex]12.5 \ mL= V_B[/tex]

12.5 milliliters of 2 M sodium hydroxide are required to neutralize 25 mL of 1 M hydrochloric acid.

Answer:

This is because the half life of second order reactions is inversely proportional to the initial concentration of the reactant.

Explanation:

The equation to half life in the second order reactions is given by:

t1/2=1/[A]initial

From the equation, you can see that as the initial concentration of A increases the denominator also increases ,thus overall value (t1/2) decreases.

Hope this helps:)

Answer:

hdfcghbjhaiedg

Explanation:

Answer:3)date geological formations

Explanation:

The ratio of the mass of U-238 to the mass of Pb-206 can be used to date geological formations.

Radioactive elements have unstable nucleus and they can be used for dating.

The ratio of the amounts of U 238 and Pb 206 in a rock sample enables the age of the rock to be estimated using the technique of radiometric dating.

Thus, the ratio of the mass of U-238 to the mass of Pb-206 can be used to date geological formations.

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Answer:

Back into the sky and sewers/drainage holes

Explanation:

Water becomes evaporated from the sun and Rain also goes into drainage holes

Into the Earth of course! Rain falls from the sky then onto the ground in the dirt making grass or flowers, or perhaps crops. Rain kan also go onto the tress in the rainforest, or maybe the beautiful Niagara Falls.

(hope this helps!)

Answer:

The second one would be one of the application of an endothermic reaction as because endothermic reaction always have the heat in the process to mix the reactants and form the products as here in a burning wood when the wood is supplied with heat then it change into products as ashes and smoke fumes So here due to the heat is involved to form the products thats the reaction is endothermic reaction.

Hope it helps

Answer:

-2

The charge on an oxygen ion is -2. An oxygen atoms contain six electrons in its valence electron shell.

Explanation:

Answer:

Molar mass of H3PO4  = 97.99 g/mol (Approx.)

Explanation:

Find:

Molar mass of H3PO4

Given;

Molar mass of H = 1.0079 g/mol

Molar mass of P = 30.974 g/mol

Molar mass of O = 15.999 g/mol

Computation:

Molar mass of H3PO4  = (1.0079)(3) + 30.974 + 15.999(4)

Molar mass of H3PO4  = 3.0237 + 30.974 + 63.996

Molar mass of H3PO4  = 97.9937

Molar mass of H3PO4  = 97.99 g/mol (Approx.)

Answer:

The above answer is correct

Explanation:

I took the test

Explanation:

A= Mercury (ll) oxide

B= Mercury and Oxygen

This is an oxidation-reduction (redox) reaction:

2 HgII + 4 e- → 2 Hg0

(reduction)

2 O-II - 4 e- → 2 O0

(oxidation)

HgO is an oxidizing agent, HgO is a reducing agent.

Answer:

Radiation refers to the emission of energy in rays or waves. Heat moves through space as energy waves. It is the type of heat one feels when sitting in front of a fireplace.

Explanation:

Answer:

An individual adapting due to memories formed from experiences with stimuli

Explanation:

Answer: I think it's 1 ATM and 0 F

Explanation:

Answer:

Volumen = 65.199 metro cúbico

Explanation:

Tal como lo conocemos

P1V1 = P2 V2

Aquí

P1 = 1,9 atmósferas

V1 = (pi) * r ^ 2 * h

Sustituyendo los valores dados, obtenemos

V1 = 3.14 * 2.8 * 2.8 * 4.6 = 113.241 metros cúbicos

V2 = por determinar

P2 = 3.3 atmósferas

Sustituyendo los valores dados y derivados en la fórmula principal, obtenemos -

1.9 atm * 113.241 metros cúbicos = 3.3 atm * V2

V2 = 1.9 atm * 113.241 metros cúbicos / 3.3 atm

V2 = 65.199 metro cúbico

Answer:

103.9 KPa

Explanation:

From the ideal gas equation;

PV=nRT

From the parameters given;

P= ?

T=250 K

V= 60L

n=3

R=0.082 atmLK-1mol-1

P= nRT/V

P= 3 × 0.082 × 250/60

P= 1.025 atm

1 atm=101325 pascals

1.025 atm = 1.025 atm × 101325 pascals/1atm

= 103.9 KPa

Answer:

103.9kPa

Explanation:

To solve this question we must use the equation:

PV = nRT

P = nRT / V

Where P is pressure in atm

n are moles of the gas = 3mol

R is gas constant = 0.082atmL/molK

T is absolute temperature = 250K

V = 60L

P = 3mol*0.082atmL/molK*250K / 60L

P = 1.025atm

As 1atm = 101.325kPa

1.025atm * (101.325kPa / 1atm) = 103.9kPa

Answer:

mass percent = (mass of solute / mass of solution) x 100%

Explanation:

Answer:

Marine debris comes from many different sources and enters the ocean in many ways. Intentional littering and dumping are a big cause of marine debris. ... Those rivers and streams can eventually carry the trash to the ocean. Improper or careless waste disposal is another big cause.

hope this helps

have a good day :)

Explanation:

Answer:

8.73 × 10²⁴ formula units

Explanation:

To calculate the number of formula units a substance contain, we multiply the number of moles by Avagadro number (6.02 × 10²³)

number of formula units = 14.50 moles × 6.02 × 10²³

= 87.29 × 10²³

= 8.73 × 10²⁴ formula units.

Answer:

The molecular formula for aspartame is C14H18N2O5, and its molar mass is about 294 g/mol. 1.2 g / 294 g/mol = 4.08 X 10-3 moles aspartame. Since each mole of aspartame has 2 moles of nitrogen, you have 8.16 X 10-3 moles of N in your 1.2 grams of aspartame.

Explanation:

Answer:

i. Sobolo is a Ghanian drink that is produced from red hibiscus flower that has an average pH of 6.7

It contains cyanidin and anthocyanins, which is a red pigment that is red in an acidic medium and changes green when introduced in a basic medium that has a high pH

The pH at the rectum of the digestive system = 5 to 8 (Slightly basic)

Therefore, what made the stool of Akosua green is that the sobolo drink changes to green in basic solution

ii. The stool which appeared green because she took sobolo turn into bright red upon mixing with the acidic WC water because of the presence of anthocyanins in sobolo, it turns red in an acidic medium

iii. Sobolo which turns green, or blue in a basic medium and red in an acidic medium can be used as a litmus solution to test the pH of a given substance

Explanation:

Sobolo or soobolo in Ghana is a name for the Hibiscus tea or tisane, which is made from calyces of the hibiscus plant, and has a sour (tangy) taste and appears bright red in color

Answer: Electrolysis is defined as the process by which electrolyte allows electric current to pass through it and is decomposed in the process.

Explanation:

Substances that allow the passage of electric current are known as conductors. Examples of conductors are metals, graphites. Metals are good conductors of electricity of which an example is LEAD.

Lead is a metal which can be extracted through the process of electrolysis. A substance in solution or liquid state like lead (II) bromide which allows electric current to pass through it and at the same time decompose by it is known as an ELECTROLYTE.

In the electrolysis of lead (II) bromide to obtain Lead,the electrolyte ionize into positive and negative ions. The positive ions migrate to the cathode and are known as captions. The negative ions migrate to the anode and are known as anions.

--> At the CATHODE: Pb2+ gains electrons and Lead is deposited

Pb2+(aq) + 2e -----> Pb(s)

--> At the anode: Br- gives up electrons and is liberated as bromine vapour.

2Br- (aq) ------> Br2(g) + 2e.

Answer:

pseudoscience

Explanation:

A pseudoscience may be defined as certain beliefs and statements or practices that are mistakenly regarded as a practice that is based on scientific method. These practices are claimed and thought to be factual as well as scientific, but they are incompatible with any scientific method.

One such pseudoscience is the belief that magnets can cure arthritis. It is a common belief that magnet therapy cab ease and provide a relief from the arthritis pain but scientific studies have confirmed that such treatments are ineffective for the arthritis pains and problems.

Answer:

121.1g

Explanation:

First, we need to convert the number of molecules of NaCl to moles (n) by dividing by Avagadro number

That is, n = number of molecules ÷ 6.02 × 10²³

n = 1.25 X 10²⁴ ÷ 6.02 × 10²³

n = 1.25/6.02 × 10^ (24-23)

n = 0.207 × 10¹

n = 2.07moles

Using the formula; mole = mass ÷ molar mass

Molar mass of NaCl = 23 + 35.5 = 58.5g/mol

mass = molar mass × mole

mass = 58.5 × 2.07

mass = 121.1g

Answer:

D; the pollen sticks to the stigma

Explanation:

When a flower is pollinated, the pollen sticks to the stigma. However, it is not always pollinated by insects (birds and other factors can as well), pollen can be transferred from different flowers (as long as they're the same species) and pollination doesn't stick to the anther.

Answer:

d

Explanation:

because when pollution occurs than the insects move to the flower to sick nectar and then pollan giains stuck in the insect body

Answer:

Meristematic Tissues. Tissues where cells are constantly dividing are called meristems or meristematic tissues. These regions produce new cells.

Explanation:

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