Answer:
12.5mg of technetium-99 remain
Explanation:
When a radioactive isotope decays in the time, its concentration follows the equation:
ln[A] = -kt + ln[A]₀
Where [A] could be taken as the mass of radioactive isotope after time t (18h),
k is rate constant = ln 2 / Half-Life = ln 2 / 6hours = 0.1155hours⁻¹
[A]₀ is initial amount of the isotope = 100.0mg
Replacing:
ln[A] = -0.1155hours⁻¹ *18hours+ ln[100.0mg]
ln[A] = 2.5257
[A] =
12.5mg of technetium-99 remain
What forms when two atoms combine?
Answer: A molecule is formed when two or more atoms combine together.
Hope this helps!
15. A substance that has a melting point of 1074 K
conducts electricity when dissolved in water, but
does not conduct electricity in the solid phase. The
substance is most likely
A) an ionic solid
C) a metallic solid
B) a network solid
D) a molecular solid
Answer:
Ionic solid.
Explanation:
Ionic solid dissociated into free ions capable of conducting electricity in aqueous solution. Ionic solids are also characterised by high melting point due to strong ionic bonds. No free ions or electrons to conduct electricity in solid form.
The substance conducts electricity when dissolved in water, but does not conduct electricity in the solid phase and will be most likely an ionic solid. Therefore, option (A) is correct.
What are ionic solids?Ionic solids can be described as made of lattices of alternating ions. They are not close-packed structures because they like ions would have to touch. Ionic solids are commonly insulators because electrons are tightly held to the ions. They have high melting points due to strong ionic bonds
Due to the strong attractive forces between ions in ionic solids, they have high melting and boiling points. An ionic compound can conduct electricity in water and when it is melted.
In solution, the ions of the ionic solids are free to move and can conduct an electrical charge. The molten state also gives freedom of movement for the ions to conduct while Ionic solids are good insulators.
The ions in the solid cannot move due to the strong attractive forces between oppositely charged ions and, therefore, they do not conduct electricity well.
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How many significant figures does 0.09749000 have
Answer:
Number of Significant Figures: 7
Explanation:
The Significant Figures are 9 7 4 9 0 0 0. Remember: the first zeros don't count!
which of the following gas samples would have the largest number of representative particles at STP?
a) 0.10 L Xe
b) 0.007 L SO3
c) 12.0 L He
d) 7.0 L O2
c) 12.0 L He would have the largest number of representative particles at STP
Further explanationGiven
The gas samples
Required
The largest number of particles
Solution
The largest number of particles = the largest amount of moles
At STP 1 mole = 22.4 L and 1 mole = 6.02 x 10²³ particles
Quickly we will be able to determine that option C has the largest number of particles because it has the largest number of volumes
or we can find the mole of each gas sample
Let's find each mole of the gas sample
a. 0.10 L Xe
[tex]\tt \dfrac{0.1}{22.4}=0.0045[/tex]
b. 0.007 L SO3
[tex]\tt \dfrac{0.007}{22.4}=0.00031[/tex]
c. 12.0 L He
[tex]\tt \dfrac{12}{22.4}=0.536[/tex]
d. 7 L O2
[tex]\tt \dfrac{7}{22.4}=0.313[/tex]
How will the calcium atom shown below achieve an octet if it takes part in an ionic bond?
a
The calcium atom will gain 8 electrons.
b
The calcium atom will lose 6 electrons.
c
The calcium atom will gain 2 electrons.
d
The calcium atom will gain 20 electrons.
e
The calcium atom will gain 6 electrons.
f
The calcium atom will lose 8 electrons.
g
The calcium atom will lose 20 electrons.
h
The calcium atom will lose 2 electrons.
Answer:
It will lose 2 electrons
Explanation:
Here we have a calcium atom, which has 20 electrons.
Those 20 electrons are in 4 shells. (2-8-8-2)
Saying there are 2 electrons in the valence shell (Shell N), to get to an octet with an ionic bond (with a group 16 element), those 2 electrons will have to go.
The graph indicates the running route for Tobias.
A graph with horizontal axis time (seconds) and vertical axis position in (meters). The line runs in straight segments from 0 seconds 0 meters to 4 seconds 10 meters to 6 seconds 5 meters to 10 seconds 10 meters to 12 seconds 15 meters to 14 seconds 5 meters to 16 seconds 22 meters to to 20 seconds 28 meters.
Which best describes his run?
A.From time 0 to 6, he went fast and then slowed down.
B.From time 6 to 10, he was at his slowest.
C.From time 12 to 14, he went very slow.
D.From time 14 to 18, he went toward the starting point.
Answer: b
Explanation:
Answer:
B
Explanation:
just took the test!!
Write the name and symbol of the ion formedwhen a sulfur atom gains two electrons. a.an aluminum atom loses three electrons. b.a nitrogen atom gains three electrons. c.a calcium atom loses two electrons.
Answer:
SULFUR: S²-
ALUMINIUM: Al³†
NITROGEN: N³-
CALCIUM: Ca²†
HURRRYYYY!!!!
Which of the following will lead to a thunderstorm?
The atmospheric factors which leads to thunderstorm are moisture, unstable air, and air way for the surface air to rise. Hence, option c is correct.
What is thunderstorm ?Thunderstorm is a natural phenomenon occurring from the collision of clouds and accompanied with electrical current and lightening. Severe thunderstorms produce convective instability .
This instability of air brings about a significant negative buoyancy in conjunction with thunderstorm downdrafts. Intense evaporation, negative buoyancy, and a powerful downdraft are produced as the dry air entrains with the cloud's wet air.
Thunderstorms also causes tilting of storms, displaces updraft from downdraft; Creates a vacuum affect at the top of storms and thus lift the air in the surface.
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How would you expect this object to behave if it starts out not moving? (The object is the circle, and the arrows show forces acting on the object.) speed up moving to the left speed up moving to the right move to the right at a constant speed move to the left at a constant speed
Answer:
its a
Explanation:
i took the test and its right
The object is the circle, and the arrows show forces acting on the object, speed up moving to the left.
what is speed ?Speed is the ratio of distance to the time in which the distance was covered, it is a scalar quantity as it has only direction and no magnitude.
The speed is represented as s=d/t, Where, s is the speed in m.s-1, d is the distance traveled in m, t is the time taken in s
There are four types of speed such as Uniform speed, Variable speed, Average speed, Instantaneous speed
Uniform speed in which the object covers equal distance at equal time , whereas variable speed is defined as when the object covers a different distance at equal time interval.
Average speed is defined as the uniform speed the ratio of total distance travelled by an object to the total time taken by the object.
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a) Of options (a) - (d) below, highlight the (unbalanced) chemical equation that represents
the combustion reaction of cellulose (like what we see with the wood burning in a
campfire above)
a) O, + H2O → C + CH1,05 + CO2
b) C6H100, + O2 + C + CO, + H,O
c) CH4,05 + CO2 → C+ O2 + H,O
d) CO, + H2O → C.H.O. + O2
Answer:
c...............
Explanation:.............................yuuuuuuuuuuuuuuuuuuuuuwoopuuuuuuuu
How do the trillions of cells in the human body get what they need to function
Which graph represents the function f(x) = 2|x|?
Answer:
It will look like a v starting the at point (0,0) with a slope of 2
Explanation:
Answer:
look at the graph
Explanation:
hope this helps, pls mark brainliest :D
explain how to find the mass of water. show your calculations as well
Answer:
You can find the mass of water by multiplying the density of water by its volume.
mass = Density x volume
Explanation:
It is very easy to find the mass of water once you know the formula of density. "Density" refers to mass per unit volume.
Density (ρ) = [tex]\frac{mass}{volume}[/tex]
Therefore, mass = ρ x volume
The density of water is 1 kg/L.
For example, if the volume of water is 500 ml, then you can get its mass by multiplying 500 ml by 1 kg/L.
Let's convert 500 ml to Liter first.
500 ml x [tex]\frac{1 L}{1,000 ml}[/tex] = 0.5 L
Now, let's compute.
mass = ρ x volume
mass = 1 kg/L x 0.5L
mass = 0.5 kg
The mass of a 500-ml water is 0.5 kg.
give 3 importance of learning about fault
Answer:
These breaks, across which slip has occurred, are called faults. ... So understanding the types and patterns of ancient fault can help geologists to ... The faulting patterns can have enormous economic importance
Give below are the four mixtures. Choose the correct one which can be separated by winnowing. (i) soybean and chickpeas (ii) wheat and rice (iii)cotton and cornflakes (iv)Banana wafers and chips Which of these can be separated by the method of winnowing?
Answer:
Banana wafers and chips
Explanation:
Winnowing is the process of separating heavier and lighter components of a mixture by blowing air through the mixture. This implies that the relative weight of the particles in the mixture determines whether they can be separated by winnowing or not.
However, chips are heavier than wafers. wafers refer to a very light snack which is easily blown away by a current of air. Hence banana chips and wafers can be separated using the method of winnowing.
A student spends 4.5 hours studying for a test. How much time is this equivalent to in seconds
Select one:
a)2,700 seconds
b)16,200 seconds
c)270 seconds
d)6,480 seconds
Conservation of mechanical energy is defined as
(a) Energy of motion
(b) Law of conservation of energy
(c) The sum of the kinetic and potential energies of an object remain a constant value unless there are forces acting on the object that cause a loss of energy overall, such a friction and air resistance.
(d) Potential energy added to kinetic energy
Help me pleasee!!!!! (revised)
Answer:
bal2 is the correct answer hope this hlps have a great rest of your day.
Explanation:
Use the image to answer the question
Cassie is working on an investigation for science. She mixes a yellow liquid and a solid chemical in a flask. Which answer best describes her results?
A.
A physical change occurred because the substances kept their properties.
B.
A physical change occurred because the liquid turned yellow.
C.
A chemical change occurred because a gas was formed from a chemical reaction.
D.
A chemical change occurred because the liquid was boiled.
PLEASE HURRY
Answer:
C. A chemical change occurred because a gas was formed from a chemical reaction
Answer:
B A physical change occurred because the liquid turned yellow.
why is
helium number 2 (the second element)
and beryllium number 4 (the fourth
element) on the periodic table ?
Answer:
See note in Explanation
Explanation:
The modern periodic table of the elements is arranged in order of increasing atomic numbers which is also in terms of the number of protons in the nucleus. That is, for any element listed on the periodic table its atomic number equals the number of protons in the nucleus. Thus, the element with 2 protons in its nucleus would be element #2 (Helium), element #3 (Lithium) has 3 protons in its nucleus and element #4 (Beryllium) has an atomic number 4 and contains 4 protons in its nucleus.
Also, this arrangement of elements finds that elements below elements 2, 3 & 4, Neon #10; sodium #11 & magnesium #12 have similar chemical and physical properties as does elements #2, #3 & #4. Such gives rise to the 'Periodic Law' => the chemical and physical properties of the elements is a periodic function of their atomic number (or, number of protons in the nucleus).
true or false? British commander Henry Hamilton was also
known as the "hair buyer" because he paid his
soldiers to cut their own hair.
if it is false give an explanation to why it is false
That is true he was known as the hair buyer
Answer:
its true.
i did it on edg 2020
Explain why ammonia is a gas at room temperature
Answer:
Originally Answered: Why is ammonia in gas form at room temperature? That is because ammonia's boiling point is -33.34 Celsius or -28 Fahrenheit. The average household temperature is about 28 to 32 Celsius depending where you live but wherever it is, it is definitely above the boiling point of ammonia.GOOD LESSONS ♡
Part F
Based on the model, do you think a fossil can form anywhere on Earth, or does fossil formation require certain
conditions? Explain your answer.
Answer:
Yes, the process of fossilisation is a continuous one. If the conditions are right, a dead plant or animal will be preserved in the rocks of the future, just as they were in the past.
Explanation:
For a fossil to form, several conditions have to be met. First of all, the animal had to live in the given area! Animals live in many environments on Earth, but not everywhere. The water above many lake bottoms and many areas of the deep ocean bottom are stagnant. The bottom water is never exchanged with surface waters, so the water contains no dissolved oxygen. Animals cannot live without oxygen, so no animals live there. In these situations, the only possibility of fossilization is if a fish or other swimming animal dies in oxygen-rich waters above, sinks down into the stagnant muddy bottom, and is buried by sediments.
Based on the model it can be said that fossil formation require certain conditions ( i.e YES )
What is fossilisation ?Fossilisation is the process of preserving plants and animals in a solid petrified form such as rocks. Fossilisation is a continous process which is seen when dead plants and animals are left to become fossils given that the necessary conditions are met.
Hence we can concude that Based on the model it can be said that fossil formation require certain conditions ( i.e YES )
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please answerrrrrrrrrrrrrrrrrrrrrrrrr
Answer: I'm in no way like an expert but I've heard water goes from an elevated area to a lower area. So it should be arrows that start at a more elevated to less elevated. Like white to brown, and orange to yellow, and stuff like that. I hope that helped? Anyway, have a lovely day!
Explanation:
Calculate the energy of a photon with a frequency of 3.20 x 10^-11 s^-1
Answer:
E = 21.22×10⁻⁴⁵ J
Explanation:
Given data:
Frequency of photon = 3.20×10⁻¹¹ s⁻¹
Energy of photon = ?
Solution:
Formula:
E = h×f
h = plancks constant = 6.63×10⁻³⁴ Js
by putting values,
E = 6.63×10⁻³⁴ Js × 3.20×10⁻¹¹ s⁻¹
E = 21.22×10⁻⁴⁵ J
While working in the lab, you observe the following volume.
What is the value that should be recorded?
Select one:
a)17.4 mL
b)18.4 mL
c)13.4 mL
d)19.4 mL
Answer:
B 18.4L
Explanation:
Answer:
The answer is 18.4 mL
The liquid is between 19 and 17
so the answer will be 18.4 mL
Which of the following parts of a forest ecosystem could not become a fossil?
A. twigs that dropped from trees
B. a dead mouse
C. a puddle
D. deer footprints in the soil
The parts of a forest ecosystem could not become a fossil are; deer footprints in the soil and a puddle.
A fossil is formed from the remains of plants and animals that have died. Anything that is not plant or animal material can never be turned into fossil. Fossil is rich in carbon.
A puddle just refers to a percolation of water. A puddle and deer footprints in the soil are not of plant or animal origin.
As such, deer footprints in the soil and a puddle could not become a fossil.
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the _ of an element is the average mass of an element naturally occurring atom, or isotopes,taking into account the _ of each isotopes
Answer:
the atomic mass of an element is the average mass of an element naturally occurring atom, or isotopes, taking into account the percentage of each isotopes
Explanation:
The atomic mass of an element is obtained by obtaining the relative abundances (in percentages) of naturally occurring atoms and the masses of the isotopes. The atomic mass can also be defined as the sum of the protons and the neutrons in the nucleus of an element.
In the periodic table, the atomic mass is indicated below the symbol of each of the elements and is usually in the decimal form.
Balance the following chemical
equation by providing the correct
coefficients.
[ ]FeBr3 + [ ]Na2S → [ ]Fe2S3 + [ ]NaBr
Answer:
Explanation:
A chemical formula can be defined as a notation that is used to show which element and how many is contained in a chemical compound.
Also, in chemistry, the sum of charges of the anion and the cation of any ionic compound is always equal to zero.
A chemical equation is considered to be balanced when the amount of reactants on the left is equal to the amount of products on the right.
Therefore;
[2]FeBr3 + [3]Na2S → [1]Fe2S3 + [6]NaBr
In the above chemical equation, we will balance the reactants in the chemical equation with the smallest coefficients possible;
[tex] 2FeBr_{3} + 3Na_{3}S ----> Fe_{2}S{3} + 6NaBr [/tex]
Two (2) moles of Iron (III) Bromide reacts with two (2) moles of Sodium Sulfide to form Iron (III) Sulfide and Sodium Bromide.
A chemical equation is shown:
C2H4 + O2 → CO2 + H2O
According to the law of conservation of mass, how many atoms of oxygen exist in the products of this reaction? (3 points)
Answer:
Explanation:
C2H4 + O2 → CO2 + H2O
eqn is unbalanced - balancing by counting no. of C n H atoms
C=2 n H=4 in one C2H4
so the reaction will form two CO2 + two H2O
counting no. of O atoms: 2*2 + 2*1
=4+2
Answer:6
Explanation: