100.0 grams of an isotope with a half-life of 36.0 hours is present at time zero. How much time will have elapsed when 25.00 grams remains?
We have that the time that will have elapsed when 25.00 grams remains is
T=72hours
From the question we are told
100.0 grams of an isotope with a half-life of 36.0 hours is present at time zero. How much time will have elapsed when 25.00 grams remains?
Generally the equation for the Half life is mathematically given as
Where
[tex]X=\frac{25}{100}\\\\X=0.25\\\\Therefore\\\\\frac{1}{2}^n=0.25\\\\n=2 half lives[/tex]
Therefore
T=2*36
T=72 hours
Hence
the time that will have elapsed when 25.00 grams remains is
T=72hours
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1. What is the name of the metal which exists in liquid state at room temperature?
(a) Sodium
(b) Potassium
(c) Mercury
(d) Bromine
2. Heterogeneous mixture in which the solute particles do not dissolve and remain suspended throughout the solvent and the solute particles can be seen with the naked eye is known as:
(a) Colloidal solution
(b) Solution
(c) Suspensions
(d) both (b) and (c)
3. In tincture of iodine, find the solute and solvent?
(a) alcohol is the solute and iodine is the solvent
(b) iodine is the solute and alcohol is the solvent
(c) any component can be considered as solute or solvent
(d) tincture of iodine is not a solution
4. A pure substance which is made up of only one kind of atom and cannot be broken into two or more simpler substances by physical or chemical means is referred to as ?
(a) a compound
(b) an element
(c) a molecule
(d) a mixture
Answer:
1. mercury.
2. suspensions.
3.iodine is the solute and alcohol is the solvent.
4. A element.
the energy level model of the atom was proposed by
Answer:
Niels Bohr
Explanation:
How do we get mass from moles?
Letter C shows that some of the heat rising from the earth's surface is trapped by gases in the atmosphere and reflected back to earth. This is known as what?
options:
Coriolis Effect
Solar Flares
Green House Effect
Windshield Effect
Fe-C-Cr alloy is covalent or ionic?
Answer:
covalent....................
What direction would this plate move? (the plate is gray in color)
options:
from West to East
from East to West
from South to North
from North to South
Answer:
from south to north thats what it look like
Explanation:
Physical Models Activity (I need help)
You have explored some interesting, informative, and amusing examples of models. Now it's time to get creative and make your own model. Here is the requirement checklist for your model:
✔ Model types can include drawings, diagrams, physical models, virtual simulations, or videos.
✔ Models must be created by you, not something selected from an online or outside source.
✔ Submit a presentation, picture, video, or screenshot of your model.
✔ Submit a one-paragraph summary describing the topic you chose, your model, what it represents, how you made it, and the specific science involved. It is important that you are using science terminology and are accurate.
Now that you know how to create and submit your model, you will need to choose a topic for your model. Choose one of the three topics listed below. Select each topic for an overview.
Conservation of Mass
Atomic Theory
Thermal Energy
The question above wants to assess your ability to create a model to represent a scientific concept. In that case, I can't create the model for you, but I'll show you how to create that template.
First, you must choose one of the topics presented in the question. I suggest that you choose the topic "Conservation of Masses," because of its simplicity, however you should choose the one you are most familiar with.
Next, you should research this topic and look at the factors that make it up.
After that, you can create your template as follows:
Use a software that has ready-made drawings, mainly geometric figures, for you to represent the elements that make up this topic.Use these drawings to represent these elements, place titles that identify them, and add arrows, which direct the viewer's attention to understand the model.You can see examples of "Conservation of Masses," models in the attached figure.
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I will brainless who can answer this all pleaseeeeejxmx Ms
answer:
black
Explanation:
black is visible
Which of the cells shown is a prokaryote?
A) muscle cell B) nerve cell C) bacterium D) red blood cell
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Answer:Infection with a pathogen does not necessarily lead to disease. Infection occurs when viruses, bacteria, or other microbes enter your body and begin to multiply. Disease occurs when the cells in your body are damaged as a result of infection and signs and symptoms of an illness appear.
Explanation:
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1. matter
2. oxygen
3. water
4. hydrogen
5. compound
hope it helps :)
• An atom of _________ has an atomic mass of ______ because it has ______ protons and _____ neutrons ?
Answer:
carbon 12 6 6
Explanation:
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The example of a unicellular organism is amoeba
Max Plank created the idea of quanta4 or quantum energy. This is?
Answer:
A theory of physics in which energy exists only in discrete quantities, called quanta. It was originated in 1900 by the German physicist Max Karl Ernst Ludwig Planck (1858–1947), who suggested that electromagnetic radiation is quantized, i.e. it can be emitted or absorbed only in tiny packets, not continuously.
Explanation:
How did james Chadwick know that neutrons are neutral ?
Answer:
In 1932, he tried similar experiments himself, and became convinced that the radiation ejected by the beryllium was in fact a neutral particle about the mass of a proton. ... Chadwick also noted that because the neutrons had no charge, they penetrated much further into a target than protons would.
Explanation:
A school bus travels 270 km in 6 hr. What is its average speed for the trip in km/hr?
Answer:
45km/hr
Explanation:
270/6=45
Which of the following is an element?
O CuO
O Na
OCH4
H20
Explanation:
na is element
others are compounds
AgNo3.
Electrolysis happening in water.
5.6l of Oxigen goes in Anod how much Ag goes on Ch?
While Brian was cutting the end of the rubber tube, during chemistry lab, he accidently cut his finger. It was a minor cut and hardly any blood was visible. Brian should __________
a. tell his teacher immediately and do as directed.
b. go to the sink and wash his hand with soap and water.
c. place a towel over the wound and keep working.
d. continue working because he is ok.
Answer:
A because even if its a minor cut, it's always a better choice to inform someone.
jeffrey is on his skateboard and starts skating down a ramp. ten seconds later he is traveling at 20.0m/s calculate the acceleration
Pots and pans that are used for cooking are often
made of copper, aluminum, and iron. Explain how metallic bonding makes these
metals suitable for this use.
Cooking materials are made of copper, aluminum, and iron because they contain free, mobile electrons owing to the metallic bond.
Metallic bonding involves a sea of electrons that is bonded to metal cations by electrostatic attraction. The electrons in the metallic bond are free to move around the material.
Because there are free electrons, when the material is heated, the electrons receive energy and move faster, this energy spreads throughout the material by conduction.
Hence, good conductors of heat such as copper, aluminum, and iron are used for cooking materials.
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Help me pls I will mark you as brain
Answer:
D. 1, 2, and 3
Explanation:
Someone pls help me I will make you brain
Answer:
the 3rd option is the answer
Which metalloid has five valence electrons in the fourth electron shell?
antimony
germanium
selenium
arsenic
Answer:
A- antimony
Explanation:
Answer:
A
Explanation:
Which group will have an electron configuration that ends in s2?
a
Alkali metals (Group 1)
b
Halogens (Group 17)
c
Alkaline earth metals (Group 2)
d
Noble gases (Group 18)
Group 2 metals have 2 electrons in their outer shell. These two electrons are usually found in the s orbital, hence the s².
The region around a nucleus in which electrons are likely to be found is called the
(1 point)
O pudding
O empty space
O atomic orbital
atomic orbit
What is the density of a 500g box whose volume is 67 ml?
Answer:
7.46 g/mLExplanation:
The density of a substance can be found by using the formula
[tex]density = \frac{mass}{volume} \\[/tex]
From the question
mass = 500 g
volume = 67 mL
We have
[tex]density = \frac{500}{67} \\ = 7.462686[/tex]
We have the final answer as
7.46 g/mLHope this helps you
Mrs. Sprague wants to determine which type of ball has the highest bounce. she
drops a tennis ball, soccer ball, then a basketball from a height of 15 feet, and
measures and records how high each type of ball bounces back up.
What is the Independent Variable in this experiment?
A.the different types of balls being tested
B.the height of the drop
C.the height of each bounce
D.the measuring tape
PLEASE HELP
Answer:
Explanation:
It's going to be the height of the drop. That is kept as a constant. The dependent variable is how high each ball bounces.
If the net force acting on a stationary object is zero, how will the object’s motion be affected?
Answer:
remain at rest
Explanation: