The half-life of a certain element is 100 days. How many half-lives will it be before only one-fourth of this element
remains?
4
50
25
2

Answers

Answer 1
It will take 2 half-lives so D.

Related Questions

How many moles of gas will occupy a volume of 2.5 l at 12.0 atm and 25c?

Answers

Answer:

1.23 moles

Explanation:

Ideal gas law

PV = n RT                 R = .082057 L-atm/mol-K

25 C = 298.15 K

12 (2.5) = n (.082057) (298.15)      n = 1.23 moles

17. Explain How is a change in oxidation number related to the process of oxidation and reduction?

Answers

Answer:

Explanation:

A change in oxidation number represents a transfer of electrons between atoms/ions. This is what happens during oxidation and reductions, where electrons are gained and lost (respectively).

Which scientist provided a foundation for John Dalton’s work on the atomic structure?
Robert Millikan
Joseph Proust
Ernest Rutherford
J. J. Thomson

Answers

Answer:

J.J. Thomson

Explanation:

Answer:

D

Explanation:

took the test

Define density please thanks!!

Answers


the degree of compactness of a substance.

Does sodium fluoride follow the octet rule? If not, which exception is it?

Answers

Answer:

Sodium fluoride (NaF) does indeed follow the octet rule without any violations.

Atoms of arsenic (As) are often added to silicon (Si) in a process called doping to change the conductivity of the silicon. How does the addition of arsenic change the conductivity of silicon?

An atom of arsenic has one fewer valence electron and more electron shells than an atom of silicon, so the conductivity decreases because the arsenic atom gains an electron.
An atom of arsenic has one more valence electron and more electron shells than an atom of silicon, so the conductivity decreases because the arsenic atom loses the electron.
An atom of arsenic has one fewer valence electron and fewer electron shells than an atom of silicon, so the conductivity increases because the arsenic atom gains an electron.
An atom of arsenic has one more valence electron and more electron shells than an atom of silicon, so the conductivity increases because the arsenic atom loses the electron.

Answers

Answer:

B.) An atom of arsenic has one more valence electron and more electron shells than an atom of silicon, so the conductivity decreases because the arsenic atom loses the electron.

Explanation:

Silicon is located in the 3rd row and 14th column in the periodic table. Arsenic is located in the 4th row and 15th column in the periodic table. This means that arsenic has one more valence electron than silicon. Since arsenic is located one row down from silicon, its valence electrons occupy higher energy orbitals.

Silicon maintains a crystal-like lattice structure. Each silicon atom is covalently connected to assume this shape. When silicon gains one extra electron from arsenic, it experiences n-type doping. This new electron is not tightly bound in the lattice structure. This allows it to move more freely and conduct more electricity. This can also be explained using band gaps. Silicon, which previously had an empty conduction band, now has one electron in this band. This lowers the band gap between the conduction and valence bands and increases conductivity.

Answer:

its d

Explanation:

witchh organsim primary cosumers

Answers

Answer:

Primary consumers are herbivores, feeding on plants

Explanation:

:)

Primary consumers are at the second trophic level of the food pyramid. This means that they eat producers. An example of a primary consumer would be a grasshopper eating grass. Primary consumers get eaten by secondary consumers, such as a rabbit who eats grass, and the rabbit gets eaten by a fox.

Which two of the following correctly describe a solution?
A. All solutions are in the liquid phase.
B. The solubility of a solute in a particular solvent is affected by temperature.
C. A solution consists of a solute and solvent.
D. The solubility of a solute in a particular solvent is affected by the densities of the
solute and solvent.

Answers

Answer:

C and A

Explanation:

i think it is because a solution is a mix of a solute and solvent, dont judge me if its wrong

How many grams is 3.2 moles of water

Answers

Answer:

similarly 1 mole of water is equivalent to molecular mass of water x 3 that is 18x3=54 gram

Explanation:

Bonds occur to make atoms more stable. Covalent bonds occur between _____

Question 41 options:

metals and noble gases because valence electrons are given to noble gases


metals and nonmetals because valence electrons are given to metals


nonmetals and nonmetals because valence electrons are shared


metals and metals because valence electrons are shared

Answers

Answer:

nonmetals and non metals because valence electrons are shared

Explanation:

please take note that ionic bond only occur between nonmetals and metals whereas covalent bonds only occur between nonmetals and nonmetals

6.0 L of gas in a piston at a pressure of 1.0 atm are compressed until the volume is 3.5 L. What is the new pressure inside the piston?

Answers

From the calculations and by the use of Boyles law, the new pressure of the gas is 1.7 atm

What are gas laws?

The term gas law is used to demonstrate the relationship between the volume, pressure, number of moles and temperature of a gas.

Using the Boyles law;

P1 = 1 atm

P2 = ?

V1 = 6 L

V2 = 3.5 L

P1V1= P2V2

P2= P1V1/V2

P2= 1 atm * 6 L/3.5 L

= 1.7 atm

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Which equation represents a combustion reaction?
1) 4fe + 3o2 = 2fe2o3
2) 2h2o = 2h2+o2
3) 2agno3 + h2s = ag2s + 2nho3
4) 2al + n2= 2aln

Answers

Answer:

2

Explanation:

do take note that combustion reactions releases oxygen.

Two children on roller skates stand facing each other. The child on the right puts her arms out and pushes away from her partner. What is the action and reaction

Answers

Answer:

They both go backward because of force.

Explanation:

The logic behind this answer is that child right and pushes away causing her to go backward meaning her partner is being pushed backwards to.

(Hope this was helpful!)

Question 1 (1 point) Which of the following summarizes cellular respiration?

Oxygen reacts with glucose to produce carbon dioxide and water, and release energy.

Light energy is changed into chemical energy.

Chemical energy is changed into light energy.

Light energy is used to join water and carbon dioxide to make oxygen and glucose​

Answers

Answer:

oxygen reacts with glucose to produce carbon dixiode into water and release energy. It is 1

Explanation:

It is A

Explanation:

Which element is number 14 on the periodic table?.

Answers

Answer:

Silicon

Explanation:

When viewing the periodic table of elements and locating atomic number 14, you will find that the element present is Silicon (Si), of which is within the metalloid elemental group.

Why do fireworks produce heat when they explode?

Answers

a fuse is attached to gunpowder present below the shell. when this fuse is ignited with a flame, the gunpowder explodes creating heat and gas that cause a buildup of pressure beneath the shell. hope this helps :)

Which of the following is not a type of energy
A. Heat from an oven.
B. Electricity in a power cord.
C. Light from a lightbulb.
D. Smoke from a fire.

Answers

Answer:

smoke from a fire Is not an example of energy

When placed in a cloud chamber, a radioactive substance does which of the following?

a. Leaves a trail of condensed water vapor.
b. Produces an electric current.
c. lonizes chemicals on the film present in the chamber.
d. Causes a liquid to reach its boiling point.

Answers

they give out particles which travel through the air until they are absorbed, either by the air itself or by some other material that blocks their path.

According to the kinetic-molecular theory, the collision between two ideal gas particles is a result of

Answers

Answer:

Neither Attraction Nor Repulsion

Explanation:

To start off,

Kinetic Molecular Theory:

A theory that describes the behavior, interaction, and movement of gas molecules; based on the idea that particles of matter are always in motion; the relationship between the microscopic qualities and the macroscopic qualities of a gas.

Repulsion:

Repulsion in chemistry stands for the force which exists between two bodies that have the same electric charge or the same magnetic polarity, this force tends to repel the bodies and separate them from each other.  

Attraction:

The attraction of the negatively charged electrons that are circling the nucleus and the positively charged protons that are inside the nucleus provokes a pill that creates a chemical bond.

To finish,

Gas particles move at random, which means there are no attractive forces between them or in their surroundings. The entire kinetic energy of two particles is preserved when they collide.

Answer:

Neither attraction nor repulsion.

Explanation:

Just took the test!

kindly help me

i am confused
i will mark you brainlist

Answers

Explanation:

a) 2 (Cr)³+ + 3 BiO3- + 4 H+ → 3 (Bi)3+ + Cr2O72- + 2 H2O

b)

have posted a similar question in the image for the phosgene i hope it helps little

Why do medical implants and prosthetics should be carefully designed when placed inside or on the surface of the body?

Answers

Answer:

because it needs to fit exactly into how your body is like

Explanation:

Sam and Albert reacted 3.5 moles of hydrogen gas with an excess of oxygen and had a percent yield of 85%. How many moles of water did they actually produce

Answers

The mole of water Sam and Albert produced would be 3.5 moles

Mole ratio

From the balanced equation of the reaction:

[tex]2H_2 (g) + O_2 (g) --- > 2H_2O (l)[/tex]

The mole ratio of hydrogen to water is 1:1.

Thus, if 3.5 moles of hydrogen gas is reacted with excess oxygen, 3.5 moles of water will also be produced.

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What is the formula for calculating the change in thermal energy?

Answers

Answer: :Change in thermal energy = mass x specific heat capacity x change in temperature.

Explanation: what it basically means is mass x heat x the change in temperature.

Change in thermal energy = mass x specific heat capacity x change in temperature.

Radiocarbon dating can be used to determine the age of a fossil because the amount of carbon-14 found in the fossil...

a. increases steadily over time.
b. decreases steadily over time.
c. is unaffected by time.
d. remains the same for the first 10 years, and then rapidly decreases.

Answers

Answer:

B

Explanation:

Carbon-14 will steadily decrease in a dead organism. Fossils are no different. Sense it's dead already, it will still be getting rid of the last bit of carbon-14 it has in a steadily way.

Imagine that the human population continues to increase, but we don't monitor or implement strategies to minimize our impact on the blue crab population.
Construct an argument supported by evidence for how increases in human populations impact the consumption of natural resources. In your answer, be
sure to include:

• the relationship between human populations and the consumption of resources

• a prediction of how the blue crab population would change with an increasing human population
evidence from the resources explored during the lesson
scientific reasoning

Answers

Answer:

The Explanation

Explanation:

:i imagine less blue crabs ngl

What kind of water is found in littoral zone of a lake?

Answers

The littoral zone of a lake is the area closest to the shore. It has very little biological activity but includes a lot of oxygen. The water in the lake's littoral zone is freshwater, free of living organisms such as plants and fish.

A mole is known by what other name?

Answers

Answer: avogadros number/constant

Explanation:

What was in Flint's water that caused 12 people to die?(1 point)

lead

total triahalomethanes

Legionella pneumophila

Escherichia coli

Answers

The presence of lead in Flint's water is what caused the death of 12 people.

Option A.

What was in Flint's water?

The Flint water crisis started in 2014 when the city of Flint, Michigan, switched its water source from Lake Huron to the Flint River as a cost-cutting measure.

The water from the Flint River was more corrosive and caused lead to leach from the pipes, contaminating the drinking water. This led to high levels of lead in the drinking water, which is a potent neurotoxin that can cause a variety of health problems, particularly in children.

The contamination also led to an outbreak of Legionnaires' disease, a severe form of pneumonia, which was linked to at least 12 deaths in the area.

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How can we prevent coral reefs from dying in the first place?

Answers

If u go deep enough we can stop by killing and eating fish

Explanation:

1. Reduce your carbon footprint

Carbon emissions also increase ocean acidity, which can impact corals and the species that depend on them.

Walking, biking, riding public transportation and carpooling are all ways you can reduce your carbon footprint

2. Conserve water to reduce pollution

All water winds up in the ocean, and pollution drives much of the damage to reefs. And runoff is what carries nutrients and contaminants into the sea.

Using less water can help minimize these impacts.

3. Get engaged

Through civic and political engagement, you can help shape your community in ways that reduce negative impacts on coral reefs. Volunteering, voting and running for public office are all ways you can become more engaged and magnify your impact on a wide range of issues.

4. Support sustainable fishing

Overfishing has a dramatic impact on coral reefs. By making informed choices about the fish you purchase and eat, you can contribute greatly to ocean health.

5. Support sustainable development and tourism

By doing research, speaking out and making informed choices when you visit tropical reefs, you can make a big impact

6. Help inform the public

Educating others about the crisis facing coral reefs is a vital part of building support, engagement and the political will to fight the human-caused pressures that are devastating reef ecosystems.

Which of the following happens when a reaction reaches dynamic equilibrium in a closed system?

A) The concentrations of the reactants and products increase.
B) The concentrations of the reactants and products remain constant
C) The rate of the forward reaction is faster than the rate of the reverse reaction.
D) The rate of the forward reaction is slower than the rate of the reverse reaction

Answers

Answer: B

Explanation:

At equilibrium, the rate of the forward reaction is equal to the rate of the reverse reaction, and thus the concentrations of the reactants and products must be constant.

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