if an element has a half-life of 30 million years and there is 12.5% of it remaining in a rock, how old is that rock

Answers

Answer 1

Answer:

The half-life of a substance is the amount of time it takes for half of that substance to decay. However, after two half-lives, half of the half remaining will decay, leaving you with one quarter of the original substance.

So, after 1 million years you will have 50% of the original substance remaining.

And, after 2 million years you will have 25% of the original substance remaining.

After 3 million years you will have 12.5% of the original substance remaining.

And after 4 million years you will have 6.25% of the original substance remaining.

Explanation:

Hope it helps:)


Related Questions

Water is carried though the trunk in the sapwood.
True
False

Answers

Answer:

true

Explanation:

the answer would be TRUE. The network of thick-walled calls brings water and nutrients up from the roots through tubes inside of the trunk to the leaves and other parts.

New forms of drug-resistant bacteria can evolve quickly because
A
when a drug kills most of the bacteria, the ones left to breed are those that have a natural resistance to the drug.

B
when scientists genetically engineer bacteria they use natural selection.

C
scientists use extinction to selectively breed bacteria.

D
a drug causes mutations in the bacteria, leaving only mutated bacteria left to breed.

Answers

Answer:

A

Explanation:

what are the functions of the following? (Make it simple)
Vacuole
Cell Membrane


Answers

Answer:

Vacuole- Function of vacuole is they help to maintain water and minerals balance in cell.

Cell Membrance- The functions of cell membrane are:

They keep toxic substances out of the cell.It only allows sensitive material to enter and exist in cell.

Possible variations of a gene that controls a specific trait

A) Heredity

B) Phenotype

C) Gene

D) Allele

Answers

Answer:

D

Explanation:

Alleles are the different possibilities for the trait (brown, blue, green.)

Possible variations of a gene that controls a specific trait are referred to as alleles. Therefore, the correct option is D.

Alleles are different types or forms of a gene that reside at the same locus on a certain chromosome. They contribute to the wide variety of traits seen within populations and can exist in several forms, such as dominant or recessive.

For example, there may be alleles for blue eyes, brown eyes, or green eyes, for a gene that affects eye color. Different alleles play a role in the variety of phenotypes (observable characteristics) that people can display.

Therefore, the correct option is D.

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In an example of natural selection, ______ cells in cancerous tumors can survive chemotherapy, and these cells go on to divide rapidly in the absence of competition from other cells.

Answers

Answer:

1. Drug-Resistant

Explanation:

Which of the following examples is NOT classified as composite volcano?
A. Mt. Fuji B. Mt. Rainier C. Mt. Mayon D. Mt. Paricutin

Answers

Answer:

C. Mt. Maton

Explanation:

not sure but hope it helps

Mt. Mayon examples is NOT classified as composite volcano.

What is Composite volcano?

Cone-shaped composite volcanoes, also known as stratovolcanoes, are formed from numerous layers of lava, pumice, ash, and tephra. Composite volcanoes typically generate tall peaks rather than rounded cones because they are composed of layers of viscous material rather than fluid lava.

Calderas are occasionally created when the peak crater collapses. The most destructive volcanic eruptions in recorded history have been caused by composite volcanoes.

Apart from Earth, Mars is the only known location in the solar system with stratovolcanoes.

Therefore, Mt. Mayon examples is NOT classified as composite volcano.

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Landfills are one source of CO2. As garbage decomposes, it releases CO2 into the air. Can you think of at least one
way that humans can reduce the amount of trash they dump in landfills?

Answers

Answer:

Recycling

Explanation:

Less garbage will be thrown away

Name the process through which gaseous exchange occurs.​

Answers

Answer:

Diffusion

Explanation:

Diffusion is the spontaneous movement of gases, without the use of any energy or effort by the body, between the alveoli and the capillaries in the lungs.

in VDJ recombination occurs in the Group of answer choices variable region of the heavy chain. constant region of the light chain. variable region of the light chain. Both the light and heavy chain.

Answers

Answer:

constant region of the light chain.

Explanation:

The VDJ recombination is defined as the process where the T cells as well as the B cells are randomly assembled from the different gene segments. These are mainly known as the variables (V), the diversity (D) and the gene (G). This is done in order to generate the unique receptors which is also called as the antigen receptors so that they can collectively recognize the different types of the molecules. It mainly occurs in the constant region of the light chain.

hey i really need help in deciding the answer for the question

Answers

 B. have a great rest of your day :)

A newly developed drug causes users to lose some muscle control and slur their words, The drug also results in a slowing of central nervous system activity. MOST likely this drug is a:

Answers

Depressants slow the central nervous system.

A newly developed drug causes users to lose some muscle control and slur their words, The drug also results in a slowing of central nervous system activity. Depressants slow the central nervous system.

What is Nervous system?

Signals are sent from the brain to the rest of the body, including the internal organs, via the nervous system. Thus, the nervous system's activity regulates a variety of functions, including the capacity to move, breathe, see, and think.

The nerve cell, or neuron, is the building block of the neurological system. There are around 100 billion neurons in the human brain. A neuron has a cell body, which contains the cell nucleus, as well as distinct extensions known as axons and dendrites.

Different neuronal types control or carry out various functions. For instance, motor neurons help the brain send signals to the muscles that cause movement.

Therefore, A newly developed drug causes users to lose some muscle control and slur their words, The drug also results in a slowing of central nervous system activity. Depressants slow the central nervous system.

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is the statement true or false? plant cells have chloroplast, but no mitochondria?​

Answers

Answer:

False

Explanation:

Plant cells have both but animal cells have only the mitochondria minus the chloroplast.

If a base is deleted, a _____ mutation occurs.
A. substitution

B. insertion

C. point

D. frameshift

Answers

Answer:

Option D. A frameshift mutation occurs.

Answer:

D. frameshift

Explanation:

If a base is deleted, a frameshift mutation occurs. Hope it helps you !!

PLZ help me I’m too slow

Answers

It would be the butterfly orchid since it is a primary producer known as an autotroph! (Is this is AP bio exam?)

Explain why it is important to prevent the extinction of species?

Answers

Answer:

Animals and plants depend upon each other, so the loss of one species affects others within that complex web of relationships.

Explanation:

Healthy ecosystems depend on plant and animal species as their foundations. When a species becomes endangered, it is a sign that the ecosystem is slowly falling apart.

I hope this helps :3

Answer:

Why is it so critical that we protect species? 1. Its ecological significance. Plant and animal species are the cornerstones of healthy ecosystems. When a species becomes endangered, it indicates that the ecosystem is deteriorating.

Explanation:

The principal enzyme involved in DNA replication is called _____________. The enzyme joins ________________ to synthesize a new _______________ strand of DNA. DNA replication is called ______________ because each new DNA molecule is made up of one original and one new strand.



complementary

DNA polymerase

nucleotides

semiconservative

Answers

Answer:

The principal enzyme involved in DNA replication is called _DNA polymerase_. The enzyme joins _nucleotides_ to synthesize a new __complementary_ strand of DNA. DNA replication is called __semiconservative__ because each new DNA molecule is made up of one original and one new strand.

Explanation:

DNA replication is the process through which DNI molecule duplicates. This event takes place during the S stage of the interphase. So when the cell divides during mitosis or meiosis, each cell will get a complete set of chromosomes.

DNI replication is semi-conservative because each new molecule carries an original DNI strand and a new one. The fact that the new molecule is composed of an original strand makes it semi-conservative. The old existing strands are used to synthesize the new complementary strand.

The origin of the replication requires helicase enzymes to break hydrogen bonds and separate the two original strands. The topoisomerase enzyme is necessary to release tension. Other proteins are also needed to join the strains and keep them separated. Once the molecule is opened, there is a region named replication forks. DNA polymerase makes the new nucleotides enter into the fork and pairs them with the corresponding nucleotide of the original strand. Adenine pairs timine, and cytosine pairs guanine.

DNA strands are antiparallel, and replication occurs only in 5´-3´direction. So one of the strands will replicate continuously, while the other strain will be formed by short fragments known as Okazaki fragments.

Primers are needed to make the DNA polymerase work. Primers are small units of RNA and are placed at the beginning of each new fragment.

What is an adaptation? Give an example of one.

Answers

Answer:

Adaptations are special skills that help animals survive in their environments. For example, in order for pelicans to catch their prey, they use their pouch-like beaks to scoop up fish. This is an example of physical adaptation; the animal is using its body parts to help it survive.

Explanation:

My answer is self-explanatory; this is not plagiarized.

It is the action of adapting to something. For example, if a wild fire wides out 40 acres of forest then all the animals that lived there would have to find somewhere else to live and adapt to their new environment.

Hope this helps!

After initially swallowing food, what is repeated until the food is ready to move on to the Omasum?
A. Acid kills the bacteria.
B. Honeycomb like ridges absorb the nutrients.
C. The animal regurgitates food for chewing until it is ready
for the the next chamber.
D. Gastric juices are secreted to break down food.

Answers

Answer:

Gastric juices are secreted to break down food

Which would most likely cause a forced migration due to loss of habitat?
a short-term change
a long-term change
death
adaptation

Answers

Answer:

short term

Explanation:

Answer:

short

Explanation:

edg

What causes 37% of all pollution?

Answers

Answer:

There are a variety of examples that cause the problematic issue of pollution- Usually air pollution can be caused by the alteration of gases, solid and liquid particles suspended into the air. If we were to contemplate on how human causes lead to pollution, vehicles exhaust fumes are possibly one of the most affecting in air pollution, as well as the exhaust from industrial factories and plants. Human reasons have majorly led to pollution.

When an evolutionary biologist designs an experiment to test a hypothesis, which term is used to describe the variable that the scientist changes among his/her groups of study organisms.

Answers

Explanation:

Controlled experiment =An experiment in which only one variable is changed

Independent variable= The variable that is deliberately changed in an experiment

Dependent variable =The variable this is observed and changes in response to the independent variable

How would you describe the process of genetic information being passed from parent to offspring in organisms like bacteria?

A. The organism undergoes mitosis and creates genetically diverse offspring

B. The organism undergoes meiosis and creates genetically diverse offspring

C. The organism undergoes binary fission and creates genetically identical offspring

D. The organism undergoes sexual reproduction and creates genetically identical offspring

Answers

Answer:

C. The organism undergoes binary fission and creates genetically identical offspring

Explanation:

This because binary fission is the means of reproduction in prokaryotic organisms like bacteria. This refer to the process where a single cell divided into two or more and each looking more exactly like the parent cell..

the process of binary fission, a particular parent cell replicate its genetic material or DNA and then divides into two parts by a process called cytokinesis and each new organism produced then receive one copy of DNA. This occur in bacteria

Question 3 of 5 Which object is at the center of the solar system in the geocentric model? A. Earth B. The Moon C. The Sun D. A group of stars

Answers

Answer:

c?

Explanation:

.........................

...

.......

Answer:

the answer is A.

Explanation:

will you please give me brainlest

Which statement is the best description of an ecosystem?​

Answers

Answer:

biological community of interacting organisms and their physical environment

8. Continental drift states that continents have moved (quickly or slowly) to their current location.

Answers

Answer:

Respondent agreed the continental drift theory, which stated that continents are constantly moving on Planet's crust. Pangaea started to break up over time, and the continents gradually shifted to their current locations.

Explanation:

16. The rate of weathering depends primarily upon the area's _______________________.

Answers

Answer:

Climate

Explanation:

Hope this is right :)

Sorry if I get it wrong

The circulatory system of the frog..

A. carries oxygen to all of the cells
B. carries food to all cells
C. carries water to all cells
D. all of the above​

Answers

Answer: A

Explanation:

The blood carries oxygen and nutrients to cells and carries waste products away.

Hemophilia is a rare recessive genetic disorder in which the recessive version of the gene does not produce blood-clotting factors. A woman whose father had hemophilia marries a normal man. They have two children: a boy and a girl. What are the chances of the boy being a hemophiliac? _________ What are the chances of the girl being a hemophiliac? _________ Show your work with a Punnett Square.

Answers

Answer:25 , 0

Explanation:

XX©(mother being the carrier as her father was hemophilia- females can only be carrier of hemophilia ) when crossed with normal father produces offspring XX©, XY, XY©, XY. Therefore chances of boy being hemophilia=(1/4)*100=25.

Chances of girl being hemophilia= 0.

Hey guys! can someone write a summary on the topic of cloning?

Answers

Answer: Cloning describes the processes used to create an exact genetic replica of another cell, tissue or organism. The copied material, which has the same genetic makeup as the original, is referred to as a clone. The most famous clone was a Scottish sheep named Dolly

Explanation:

Answer:

Write your own work.  I mean I know you did just had my answer deleted because I called you out the first time.  So take the advice

Explanation:

please help me in Science grade 8th

Answers

Answer:

Both earthquake and volcanoes are concentrated in specific regions.

Explanation:

The distribution of earthquake on earth is concentrated in specific zones where the plate tectonic meets or fuse with each other. Volcanoes are also concentrated in specific regions on the earth. Most volcanoes are concentrated on the edges of continents, on island chains, or long mountain ranges beneath the sea. There is a great relationship between earthquake and volcanoes because volcanic eruptions is the cause of earthquake in a region.

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