Answer:
After 7.648 days, you will see one quarter.
Explanation:
1 → 0.5 → 0.25
Since half life of radon-222 is 3.824 days, you need twice this time to get one quarter at the end.
2 ⋅ 3.824 = 7.648 days.
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Refer to the Newsela article "How You Can Make a Solar Oven To Cook with a Pizza Box."
What is the author's purpose in mentioning variables in designing the solar oven?
to show how easy it is to produce solar energy
to encourage readers to vary the design
to explain how wasteful solar energy production can be
to show the author did not think too hard about the design
Answer:
To encourage readers to vary the design
Explanation:
what is the definition of chemical formula?
Answer:
A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus and minus signs. These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a chemical name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulae can fully specify the structure of only the simplest of molecules and chemical substances, and are generally more limited in power than are chemical names and structural formulae.
Explanation:
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Which of the following elements would be brittle?
Sulfur
Magnesium
Rubidium
Lithium
Answer:
Sulfur
Explanation:
What is the right answer?
Answer:
Option C
Explanation:
In Lewis dot structure the valence electrons are represented as dots around the symbol.
For example,
In hydrogen valence electron is only one it can be represented as,
H·
We know that in covalent bonding atoms share their electron to complete the octet. Thus, their Lewis dot structure would be represented as,
H:H
This is the Lewis dot structure of H₂.
In given atom X their are 2 valence electrons (3s²) thus its Lewis dot structure contain two dots around the symbol.
Option C is correct answer because it has only two dots which actually represent valence electrons.
Other options are incorrect because symbol X has more than two electrons/dots.
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Answer:
This shoes the soda lime defusing to limewater turning into germinating seeding which defuses back to limewater
Explanation:
A penny is 2.5 g. How many kilograms does a penny weigh?
Answer:
The penny now weighs 0.0025kg
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Which isotope has 45 neutrons?
O A. 80,36KT
OB. 80,35Br
O C. 78,345e
O D. 34,17C1
Answer:
Br.
neutron = mass number - atomic number
youcan see the answer at the pic
The isotope that has 45 neutrons is B. 80,35Br.
What is the isotope?The neutron can be obtained by subtracting the protons from the mass number. In the question, we have a proton that is numbered, 35 and a mass number of 80.
So, to get the neutron, we would subtract the protons from the mass number as follows;
80 - 35 = 45. The element that is described by this data is Bromine. Therefore, the correct option number is B. 80,35Br.
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Calculate the enthalpy change to raise the temperature of 180.0 g of water from 10.0°C to 40.0°C. The molar heat capacity for water is 75.3 J/Kmol. a. What values have you been given? b. What value are you trying to find? c. Which heat equation do you need? d. Now solve the problem.
Answer:
22572J
Explanation:
a) The following values have been given:
Mass of water = 180.0g
Initial temperature = 10°C
Final temperature = 40°C
molar heat capacity for water = 75.3J/Kmol
To calculate the specific heat capacity of water (c), we divide the molar heat capacity by molar mass of water (18g/mol)
That is; 75.3/18
= 4.183 Jg/K
b) The enthalpy change denoted by ∆H is the value we are trying to find.
c) To find enthalpy change (∆H), we use the formula:
∆H = m × c × ∆T
Where; m= mass
c= specific heat capacity
∆T= change in temperature =
(final temp - initial temp)
∆H = m × c × ∆T
∆H = 180 × 4.18 × (40-10)
∆H = 180 × 4.18 × 30
∆H = 22572J
During the day, the earth is heated up by the sun. The land gets hotter than the sea because it takes less energy to increase the land's temperature than to increase the sea's temperature. The land heats the air near it. This air rises and is replaced by cool air from the ocean, creating a "sea" breeze that blows from the ocean to the land during the day. Which forms of heat transfer are described above as helping to create a sea breeze? A. convection only B. radiation only C. convection and conduction D. conduction and radiation
Answer:
C. convection and conduction
Explanation:
A sea breeze is a phenomenon that occurs during hot summer days when the sun transfers its heat to the earth surface by convection the land absorbs energy much easier than the seawater. As a result, the air above land will become warmer and as we know warmer air is lighter so this air will rise-up the air above the sea will now move from sea to the land to balance this air also there will be heat exchange between land air and the sea air by conduction and hence together they will create a phenomenon called a 'sea breeze'.
A neutral (net charge
zero) atom of silicon contains:
A
28.09 electrons
B
16 electrons
C
14 electrons
D
38 electrons
Answer:
C 14
Explanation:
Silicon atom has 14 protons. Given that a positive and a negative neutralize each other you need 14 electrons to neutralize the 14 protons.
What do these two changes have in common?
an old sandwich rotting in a trashcan
and baking cookies
Identify the property of the matter described below.
Alcohol floats on top of the water.
A-pH
B-conductivity
C-density
D-luster
Answer: C.
Explanation: Alcohol floats on oil and water sinks in oil. Water, alcohol, and oil layer well because of their densities, but also because the oil layer does not dissolve in either liquid. The oil keeps the water and alcohol separated so that they do not dissolve in one another. ... Water sinks because it is more dense than oil.
cy sprints 100 meters in 13 seconds going south. what is his average velocity?
Answer:
Explanation:
This should be in physics.
d = 100 meters south
t = 13 seconds
v = d/t
v = 100 / 13
v = 7.69 m/s going south.
The point is that you have to specify the direction.
is Mo2S6 ionic or covalent
Answer: Ionic
Explanation:
Answer:
ionic
Explanation:
Explain what is meant by the term "excited state" as it applies to an electron. Is an electron in an excited state higher or lower in energy than an electron in the ground state? Is an electron in an excited state more or less stable than an electron in the ground state?
Answer:
Excited state of an electron is the state attained by an electron after it has absorbed energy and it moves further from the nucleus.
an electron is at higher energy when excited and at lower energy when at ground state.
an excited electron is less stable due to the decrease in the nuclear force of attraction and the grounded electron is more stable due to it's close distance to the nucleus.
An electron in excited state has its electron present in higher energy level while an electron in ground state is present in lower energy level.
What is an energy level ?Electrons present in an atom revolve in different orbits which are stationary states and are also called as energy levels. The energy levels are numbered as integers which are also called as principal quantum numbers.
Energy of the stationary state is given as E= -R
1/n² where R
is the Rydberg's constant. When an electron is excited, and it moves from lower to higher energy levels there is absorption of energy, while when it moves from higher energy level to lower energy level it radiates or gives out energy in the form of radiation.
They can also be defined as the distances between electron and nucleus of an atom . Electrons present in K energy level have least energy .Energy level diagrams are studied to understand nature of bonding , placement of electrons in orbits and and elemental behavior under certain conditions.
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Which of the following is the proper scientific notation for the number
18,200?
O A. .182 x 105
B. 1.82 x 104
O c. 18200 x 100
O D. 182 x 102
The Answer fam is......... 1.82 × 10^4, Hence It's B)
susan calculates the heat energy released when water condenses using Q = mCΔT. explain why her calculation is incorrect?
You need to find the entropy of fusion in order to find this out.
what is the ionic charge lf this atom
Answer:
An ionic charge of 2-
Explanation:
The number of electrons is 8 and the number of protons is 2, subtract the two and the difference is the ionic charge. Hope this helps! :)
Answer:
This answer would be 2
Explanation:
The way that I have always done it is you put protons in tally marks (without crossing) over the top of the neutrons and mark them out one by one and whichever one that you have leftover that is your charge.
Hope this helps!
In science class, a student is given a copper cylinder to investigate. The student measures the mass of the cylinder as 53.76 grams. The
student measures the volume of the copper as 6 cm. Which additional property of the copper can the student determine from these
measurements?
Answer:
From these two values, i.e. mass and volume, density of the copper cylinder can be calculated.
Formula of density is :
Density = Mass / volume.
Now we have mass: 53.76g and volume 6cm³
Density = 53.76 / 6
Density= 8.96 g/cm³
Describe how calcium and fluorine bond together to form calcium fluoride. The electron arrangement of each atom is shown.
Answer:
Detail is given below.
Explanation:
Calcium is alkaline earth metal. It has two valance electron. Thus calcium needs six more electron to complete the octet. Thus, its very easy for calcium to remove its two electron and get complete octet.
Electronic configuration of Ca:
Ca₂₀ = [Ar] 4s²
While,
Fluorine is halogen. It has seven valance electrons. It needed only one electron to complete the octet. When it combine with calcium , calcium loses two electrons thus two atom of fluorine combine with one atom of fluorine and stable compound calcium fluoride is formed.
Electronic configuration of F:
F₉ = [He] 2s² 2p⁵
Chemical equation:
Ca + F₂ → CaF₂
An object has a mass of 4 grams and a volume of 2 cm3. What is the density of the object
Answer:
The answer is 2.0 g/cm³Explanation:
The density of a substance can be found by using the formula
[tex]density = \frac{mass}{volume} \\ [/tex]
From the question
mass = 4 g
volume = 2 cm³
We have
[tex]density = \frac{4}{2} \\ [/tex]
We have the final answer as
2.0 g/cm³Hope this helps you
Answer:
D = 2 g/cm³
Explanation:
Density = mass over volume
D= m/v
Step 1: Define
m= 4 grams
v= 2 cm³
Step 2: Substitute and Evaluate
D= 4 g/2 cm³
D= 2 g/cm³
what are the 20 element
Answer:
you shoudl ask this question more clearly?
Explanation:
Answer:
The 20th Element is Calcium (Ca).
The 20 Elements are:
Hydrogen
helium
lithium
berilium
boron
carbon
nitrogen
oxygen
flourine
neon
sodium
magnesium
aluminium
silicon
phosphorus
sulphur
chlorine
argon
potassium
calcium
Carbon is considered an element, while carbon dioxide is considered a compound. This is because carbon dioxide is
Answer: This is because carbone dioxyde is composed of more than just an atom of carbon , it’s composed of 2 atoms of oxygen and one atom of carbon .
* I hope it was helpful , good luck :) *
A cup of hot water contains fewer molecules than a tub of hot water. This same cup of hot water will freeze faster than a tub of hot water. The total thermal energy of a system is not only dependent on the state of the material but also on the (resistance, heat, temp, half-life) and the total number of (atoms, currents, compounds, electromagnetic waves) in the system.
Answer:
The correct options are;
1) Heat
2) Atoms
Explanation:
The heat required to raise a unit mass of a substance by one degree which is the specific heat capacity of the substance, is a quantity characteristic of a given substance and the amount of temperature change experienced by the substance when an amount of heat energy transferred to the substance is a function of the mass of the substance, which is a function of the number of atoms present in the substance.
So also, the total thermal energy that is stored by a substance, that causes a given amount of temperature change, is a function of the heat capacity of the substance.
Which of the following is an example of very early scientific research?
sleeping in caves to avoid predation by animals
painting pictures and symbols on cave walls
making baskets from reeds
banging rocks together to see which make a spark and create fire
Answer:
banging rocks together to see which make make a spark and create fire painting pictures is an example of art and sleeping in caves is survival
Which best explains the process of meiosis?
Meiosis includes cytokinesis, which divides the cell's DNA.
Meiosis is a series of steps that divides the cell's cytoplasm.
Meiosis includes interphase, which divides the cell's cytoplasm.
Meiosis is a series of steps that divides the cell's DNA.
Answer:
D
Explanation:
Meiosis is a series of steps that divides the cell's DNA best explains the process of meiosis. Therefore, option D is correct.
What is meiosis ?A type of cell division in which each daughter cell receives half the DNA of the parent cell. In mammals, meiosis occurs during the formation of egg and sperm cells.
Due to the fact that cell division occurs twice during meiosis, a single starting cell can produce four gametes (eggs or sperm). Cells go through four stages during each round of division: prophase, metaphase, anaphase, and telophase.
Meiosis is also important for allowing genetic diversity and facilitating the repair of genetic defects via recombination.
Daughter cells are diploid after meiosis and have twice as much genetic material, which can be divided in an infinite number of ways.
Thus, option D is correct.
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Please help!!!
When 38 g of a metal at 92 °C is added to
43 g of water at 22°C, the temperature of the
water rises to 30°C. What is the specific heat
capacity of the metal? Assume no heat was
lost to the surroundings.
Answer in units of
J/g degrees C
The specific heat capacity of the metal : 0.610 J/g° C
Further explanationThe law of conservation of energy can be applied to heat changes, i.e. the heat received/absorbed is the same as the heat released
Q abs = Q received
Heat can be calculated using the formula:
Q = mc∆T
Q = heat, J
m = mass, g
c = specific heat, joules / g ° C
∆T = temperature difference, ° C / K
∆T = T(final temp) - T(initial temp)
mass of metal = 38 g
T initial metal = 92 °C
mass of water = 43 g
T final water = 30 °C
T initial water = 22°C
c water = 4.18 J/g° C
Heat absorbed by water[tex]\tt Q=m.c.\Delta T\\\\Q=43\times 4.18\times (30-22^oC)\\\\Q=1437.92~J[/tex]
the specific heat capacity of the metalQ water = Q metal
[tex]\tt 1437.92=38\times c\times (92-30)\\\\c=0.610~J/g^oC[/tex]
True/False: When a substance is heated, the change in energy causes the bonds between particles to become stronger.
Answer:
false
Explanation:
the energy causes the bonds to become looser
What does the “188” represent in Tantalum-188
A. mass number
B. atomic number
C. mass defect
Answer:
mass number
Explanation:
When there is an element name followed by a dash and then a number, the number simply represents the mass number.
for example:
Oxygen- 18
18 represents the mass number of this particular isotope
Your aquarium looks blurred and you wanted to clean it.How will you use recantation technique to separate water from the pebbles and other designs
Answer:
why do you not ask to your maam the answer