Thallium-207 has a half-life of 4.77 minutes. If an initial sample weighed 155 grams, and
now only weighs 2.42 grams, how many half-lives have occurred?
A.4
B.6
C.5
D.3

Answers

Answer 1

Answer:

6

Explanation:

You divide the initial sample weight (155) by 2 until you get to 2.42.


Related Questions

Please help I will mark you brainiest
What are one advantage and one disadvantage of sexual reproduction?
What is one advantage and one disadvantage of asexual reproduction?

Answers

Answer:asexual- Energy is not required to find a mate. Offspring are genetic clones. A negative mutation can make asexually produced organisms susceptible to disease and can destroy large numbers of offspring. Some methods of asexual reproduction produce offspring that are close together and compete for food and space.

Explanation:During sexual reproduction the genetic material of two individuals is combined to produce genetically diverse offspring that differ from their parents.

Convert 623g of Fe to grams

Answers

Answer: The answer is 11.15587787626466 or rounded up it will be 11.2 mol.

Explanation: By converting Grams of any element it will be in moles which is grams in philosiphical terms. But by converting Fe(or iron) It is called a Convertment of measurement units.

Explain the Anchoring Phenomenon (summary)

Answers

An anchoring phenomenon anchors all of the learning within a unit. So, it is a unit level event that the classroom is trying to make sense of as they engage in a series of lessons.

Since the questions the students ask about the anchor drive the learning within the unit, the anchor should be complex and require an understanding of several big science ideas to explain.

At strategic moments, the class revisits the anchoring phenomenon to review their initial questions to see which they have answered, which they are making progress on, and what new questions they may have to help us continue learning about the phenomenon.

Throughout the unit, the classroom and each student should be given opportunities to share their thinking and how it relates to the anchoring phenomenon.
YOU SHOULD PUT IT IN YOUR OWN WORDS THOUGH <3

You're provided a 0.50 M solution of HCl. How many moles of HCl are present in 25 ml of this solution? ​

Answers

Answer:

0.0125 moles of HCl

Explanation:

(0.50 mol/L)(0.025 L) = 0.0125 moles of HCl

Balance and indicate what type of reaction

C6H12 + O2 → CO2 + H2O

Answers

C6H12 + 9O2 → 6CO2 + 6H2O

This is a Combustion Reaction

Balanced equation is [tex]C_6H_{12}[/tex] + [tex]9O_2[/tex] → [tex]6CO_2[/tex] + [tex]6H_2O[/tex].

What is the balanced equation?

A balanced chemical equation occurs when the number of the atoms involved on the reactants side is equal to the number of atoms on the products side.

Balanced equation is [tex]C_6H_{12}[/tex] + [tex]9O_2[/tex] → [tex]6CO_2[/tex] + [tex]6H_2O[/tex]. Where there are 6 carbon atoms, 18 oxygen atoms, and 12 hydrogen atoms.

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The tapir and agouti are ___________ found in the Amazon Rainforest.
A.Carnivores
B.Omnivores
C. Herbivores
D. Decomposers
"science"

Answers

The tapir and agouti are herbivores found in the Amazon rainforest
C

Help please !!!!!!!!!!!!

Answers

the answer to your question is a increase

how does H3O+ and OH- relate to acids, bases, and the pH scale?​

Answers

Answer:

For pure water, the values of [H3O+] and [OH-] are equal and thus their values are both 1.0 x 10-7. If there is an equal amount of acid and base present in any solution, the solution is called "neutral" and the pH of the solution is 7. ... The sum of the pH and pOH must always equal 14.

Explanation:

HELP!!!!!What is the molar mass of a gas which has a density of .249 g/L at 20.0 degrees Celsius and a pressure of .95 atm?

Answers

Answer:

6.31g/mol

Explanation:

Using the ideal gas equation;

PV = nRT

Where;

P = pressure (atm)

V = volume (L)

n = number of moles (mol)

R = gas law constant (0.0821 Latm/molK)

T = temperature (K)

Mole (n) = mass (m)/molar mass (Mm)

* Mm = m/n

Also, density (p) = mass (m) ÷ volume (V)

PV = nRT

Since n = M/Mm

PV = M/Mm. RT

PV × Mm = m × RT

Divide both sides by V

P × Mm = m/V × RT

Since p = m/V

P × Mm = p × RT

Mm = p × RT/P

Mm = 0.249 × 0.0821 × 293/0.95

Mm = 5.989 ÷ 0.95

Mm = 6.31g/mol

help me get this right no links

Answers

Answer:

D

Explanation:

Because the Earth rotates through two tidal “bulges” every lunar day, coastal areas experience two high and two low tides every 24 hours and 50 minutes!!!

What is the name of this molecule?
Η Η
H-C=C-C-C-H
H H
A. 3-butyne
B. 4-butyne
C. 2-butyne
O D. 1-butyne

Answers

D. 1-butyne.

The name of this molecule is 1-butyne.

The name of this molecule is 1-butyne. D is correct.

What is IUPAC nomenclature?

IUPAC nomenclature of organic chemistry is a method of naming organic chemical compounds as given by the International Union of Pure and Applied Chemistry (IUPAC).

There are 3 main parts of IUPAC nomenclature -

1. Prefix

2. Root word

3. Suffix

We have to select the longest continuous chain in a compound and give prefixes as the substituents. Root word will the part which depends on no. of carbon atoms such as meth or eth. And in suffix we focus on type of carbon chain whether it is saturated or not and also the functional group.

Here, we can say that the numbering will be started from the carbon having triple bond and it is present at first position.

Therefore, The name of this molecule is 1-butyne. D is correct.

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An object has an actual mass of 34.85 grams. Johnny measures the object to have a mass of 35 grams after rounding. What is Johnny's percent error of the object?

Answers

Answer:

1.15.........................

please help me with this question !​

Answers

Answer: i dont understand

Explanation:

Question

What is the name of this ben zene ?

the name of this benzene is benzene circle

if you also don't understand the go in this link

https://en.m.wikipedia.org/wiki/File:Benzene_circle.svg

plz give me brainliest+ thanks i need it to reach in expert : )

PLEASE HELP!

See picture

Answers

Answer:

See Explanation

Explanation:

The equation of the reaction;

KHSO4(aq) + KOH(aq) -------> K2SO4(aq) + H2O(l)

Number of moles of KHSO4 = 49.6 g/136.169 g/mol = 0.36 moles

Since the reaction is in a mole ratio of 1:1, 0.36 moles of K2SO4 is produced.

Number of moles of KOH = 25.3 g/56.1056 g/mol = 0.45 moles

Since the reaction is 1:1, 0.45 moles of K2SO4 is produced

Hence K2SO4 is the limiting reactant.

Mass of K2SO4 formed = 0.36 moles of K2SO4 * 174.26 g/mol = 62.7 g

So;

1 mole of KHSO4 reacts with 1 mole of KOH

0.36 moles of KHSO4 reacts with 0.36 * 1/1 = 0.36 moles of KOH

Amount of excess KOH = 0.45 moles - 0.36 moles = 0.09 moles

Mass of excess KOH = 0.09 moles * 56.1056 g/mol  = 5 g of excess KOH

The word “covalent” can be broken into two parts: “co” and “valent.” The “co” part means
“together.” To what does the “valent” part refer?
A. Outer electrons
B. Atoms
C. Protons
D. Nuclei
E. Inner electrons

Answers

Answer:

Outer electrons.

Explanation:

All bonds are localized bonds formed between two atoms by the donation of electrons from each atom.

Which description applies to all atoms of an element? flammable visible under a microscope different alike

Answers

Answer:

I think its alike.... Pretty sure actually

Lana balanced an equation so that the result was 2C2H3Br + 5O2 → 4CO2 + 2H2O + 2HBr. Which most likely represents the starting equation?

Answers

Answer:

C2H3Br + O2 → CO2 + H2O + HBr

Explanation:

The term balancing of chemical reaction equation has a unique meaning in chemistry. What it actually means is to ensure that the number of atoms of each element on the left hand side of reaction equation becomes equal to the number of atoms of the same element on the right hand side of the reaction equation.

When we look at the equation; C2H3Br + O2 → CO2 + H2O + HBr, the number of atoms of each element on the left and right hand sides of the given equation are not the same hence the equation is unbalanced.

If we look at the equation; 2C2H3Br + 5O2 → 4CO2 + 2H2O + 2HBr, the number of atoms of each element on both sides of the reaction equation are now equal, thus the later equation is the balanced version of the former.

Answer:

C2H3Br + O2 → CO2 + H2O + HBr

Explanation:

given a mixture of lead to oxide ammonium chloride and sodium chloride describe how a mixture can be separated to obtain a sample each​

Answers

Answer:

There are way in separating mixtures of chloride salts such as that of sodium chloride and ammonium chloride. It can be done by crystallization, filtration, and sublimation. The easiest method among the three is separation by sublimation.

What is the concentration of a solution made by dissolving 0.99mol of acetic acid in enough water to make 0.58L of solution?

Answers

Answer:

[CH₃COOH] = 1.70 M

Explanation:

When we talk about concentration we can determine Molarity

Molarity determines the moles of solute that are contained in 1L of solution.

In this case our solute is the acetic acid.

M = mol/L

M = 0.99 mol /0.58L → 1.70 M

We can also make a rule of three

In 0.58 L of solution we have 0.99 moles of solute

In 1 L of solution we may have (1 . 0.99) / 0.58 = 1.70 moles

Acetic acid is a weak acid, partially dissociated in water.

CH₃COOH  +  H₂O  ⇄  CH₃COO⁻  +  H₃O⁺     Ka

What are the materials that good conductors and insulators?​

Answers

Conductors

Silver

Gold

Copper

Aluminum

Mercury

Steel

Iron

Seawater

Concrete

Mercury

___________________

insulators

Aluminum foil

Glass

Air

Plastic

Rubber

Porcelain

Wood

What type of particle has no electrical charge? A. proton B. neutron C. electron D. nucleus

Answers

Answer:

B

Explanation:

Neutron, neutral subatomic particle that is a constituent of every atomic nucleus except ordinary hydrogen. It has no electric charge and a rest mass equal to 1.67493 × 10−27 kg—marginally greater than that of the proton but nearly 1,839 times greater than that of the electron.

100 mL of an NaOH solution is neutralized by 50 mL of a 0.5M HCl solution. What is the morality of the NaOH solution?

Answers

Answer:

0.25M

Explanation:

acording to M1V1/M2V2=n1/n2

How many grams are in 5.4 moles of K2SO4

Answers

Answer:

The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles K2SO4, or 174.2592 grams.

Explanation:

The potassium sulphate( [tex]K_{2} SO_{4}[/tex] )contain 940.95 gram in 5.4 moles.

What is mole?

A mole is described as the quantity of a material that includes precisely 6.02214076 X [tex]10^{23}[/tex] of the substance's elementary constituents.

Given data:

Mole = 5.4

Molar mass = 174.25 g/mol

Mass = ?

Mole can be calculated by using the formula:

Mole = mass / molar mass

Put the value of given data in above equation.

Mass = Mole × molar mass

Mass = 5.4 mole × 174.25 g/mol

Mass = 940.95 gram

Therefore, there are 940.95 gram in [tex]K_{2} SO_{4}[/tex]

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If 3 moles of Mg were reacted, how many moles of
0, were also reacted?
2 Mg + O2 → 2 Mgo

Answers

Chu papi 02 806 mpg 2mg

PLEASE HELP! CHEMISTRY!
Solution A has a pH of 2.0. Solution B has a pH of 5.0. Which solution is more acidic? Based on the H+ ion concentrations in the two solutions, how many times more acidic?

Answers

Answer:

solution A

Explanation:

it is because solution A has a pH of 2.0 and solution B has the pH of 5.0 and also whose number is greater than the solution A .That is why it is acidic

Which would require less energy, moving two particles of the same charge together, or moving two particles of opposite charge close together? Why? (Explain)

Answers

Answer:

Moving two particles of the opposite charge close together.

Explanation:

Think about it.

Opposites attract.

When you attempt to move particles with the same charges, a force is created.

hola estoy aburrido alguien para hablar

Answers

Answer:

yoooo si se puede jejeje

Explanation:

Answer:

Explanation:

hola como esta yo tan biene es  aburrido

22. Which statement describes the likely metabolic impact of cyanide
production on clover plants?
M. Cyanide is nontoxic to clover plants because they produce ATP without
the electron transport in the mitochondria.
P. Cyanide is toxic to clover plants because they use cytochrome c oxidase
for electron transport in the mitochondria.
R. Cyanide is toxic to clover plants because they use cytochrome c oxidase
for ATP synthesis in the chloroplasts.
s. Cyanide is nontoxic to clover plants because they carry out electron
transport in chloroplasts rather than in mitochondria.

Answers

Answer:

M

Explanation:

Hope it helped u alot

P. Cyanide is toxic to clover plants because they use cytochrome c oxidase for electron transport in the mitochondria.

The correct option is B.

Where is cyanide found?

Various bacteria, fungi, and algae have the ability to produce cyanides. Tapioca, spinach, willow shoots, almonds, string beans, fruit seeds, and car fumes are other items that contain cyanides.

What goods include cyanide?

Smoking cigarettes and the byproducts of the combustion of synthetic fibers, including plastics, contain cyanide. Combustion products are chemicals that are released while combustion. The paper production, textiles, and plastics all use cyanide. The chemicals used it to develop pictures include it. Unfortunately, cyanide is not like other materials. By utilizing this approach, you simply cannot develop a natural tolerance to cyanide.

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The complete question is -

Which statement describes the likely metabolic impact of cyanide

production on clover plants?

A-M. Cyanide is nontoxic to clover plants because they produce ATP without the electron transport in the mitochondria.

B-P. Cyanide is toxic to clover plants because they use cytochrome c oxidase for electron transport in the mitochondria.

C-R. Cyanide is toxic to clover plants because they use cytochrome c oxidase for ATP synthesis in the chloroplasts.

D-S. Cyanide is nontoxic to clover plants because they carry out electron

transport in chloroplasts rather than in mitochondria.

The initial temperature of a reaction is 24.7 °C. The temperature decreases by 3.2 °C. What is the new temperature of the reaction? Someone help

Answers

Answer:

I think it's 21.5 *C

Explanation:

Read the given expression.
Effective nuclear charge = atomic number - x
Which of the following explains the identity of X and its trends across a period? (5 points)
X is the screening constant, and it increases across a period.
X is the screening constant, and it remains constant across a period.
X is the number of outermost electrons, and it increases across a period.
X is the number of outermost electrons, and it remains constant across a period.

Answers

Answer:

Option 2: X is the screening constant, & it remains constant across a period.

Explanation:

I took the test and got the question correct :)

As we move across the period, X is the screening constant, and it remains constant across a period.

As we move across the period, the size of atoms become smaller because of an increase in the size of the nuclear charge. This leads to a decrease in atomic radius.

As the size of atom decreases, the screening effect on the outermost electron decreases accordingly. Hence, as we move across the period, X is the screening constant, and it remains constant across a period. This is because, no new shells are added across the period.

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