Answer:
Chemical changes cause a substance to change into an entire substance with a new chemical formula. Chemical changes are also known as chemical reactions. The “ingredients” of a reaction are called reactants, and the results are called products.
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All the following are examples of selective breeding EXCEPT a wild dog that finds and mates with a domestic dog. neutering a horse that is particularly small for its breed. adding sheep from another country to the bloodline to help combat disease. purposely mating larger pigs to increase the amount of meat produced.
Answer:
A. a wild dog that finds and mates with a domestic dog.
Explanation:
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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:
Which of the following elements would be brittle?
Sulfur
Magnesium
Rubidium
Lithium
Answer:
Sulfur
Explanation:
The half life of radon 222 is 3.824 days, how much time must pass of one fourth of a given amount of radon to remain?
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.
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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You will learn in this course that organic compounds have covalent bonds with a significant amount of energy stored in them. This is why we burn fossil fuels to generate energy to heat our homes or drive our cars. Given this information, which of the compounds listed below would you expect to have the most energy is its carbon-carbon bond?
Answer:
See explanation
Explanation:
This question is obviously supposed to be a multiple choice question but the options are missing.
However, the question intends to test the student's knowledge about combustion of fossil fuels. Fossil fuels are mostly composed of hydrocarbons of different chain lengths.
The longer the chain length, the greater the energy released when the compound is burnt since there are more energy stored in its bonds.
Hence, the correct answer to this question will be the option that contains the greatest number of C-C and C-H bonds.
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.
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if three electrons are available to fill three empty 6p atomic orbitals, how will the electrons be distributed in the three orbitals
a.) one electron in each orbital
b.)two electrons in one orbital, one in another, none in third
c.) three in one orbital, one in other two
d.) cannot be predicted, determined by random chance
Answer:
A) one electron in each orbital
Explanation:
Orbitals get electrons one at a time. If there are three electrons and three empty orbitals, then one electron will go into one orbital!
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!
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
An ideal sample weighing 1.28g at 127C (temp) and 1 atm has a volume of 0.250L. Determine the molar mass of the gas.
Answer:
Molar mass of gas = 160 g/mol
Explanation:
Given data:
Mass of sample gas = 1.28 g
Temperature of sample gas = 127°C (127+273 = 400K)
Pressure of sample gas = 1 atm
Volume of sample gas = 0.250 L
Molar mass of gas = ?
Solution:
Formula:
PV = nRT
R = general gas constant = 0.0821 atm.L/ mol.K
Now we will put the values in formula.
1 atm × 0.250 L = n × 0.0821 atm.L/ mol.K ×400K
0.250 L.atm = n ×32.84atm.L/ mol
n = 0.250 L.atm/32.84atm.L/ mol
n = 0.008 mol
Molar mass of gas:
Number of moles = Mass/molar mass
0.008 mol = 1.28 g / molar mass
Molar mass = 1.28 g / 0.008 mol
Molar mass = 160 g/mol
A train in Japan can travel 813.5 miles in 5 hours
Answer:
162.7miles/hr
Explanation:
Given parameters:
Distance covered by the train = 813.5miles
Time taken = 5hours
Unknown:
Speed of the train = ?
Solution:
Speed is a physical quantity.
It is mathematically expressed as;
Speed = [tex]\frac{distance}{time}[/tex]
So, input parameters and solve;
Speed = [tex]\frac{813.5}{5}[/tex] = 162.7miles/hr
i need help please!
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Answer:
Earth is pulling up on the book with a force of 4n i think
Explanation:
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]
A penny is 2.5 g. How many kilograms does a penny weigh?
Answer:
The penny now weighs 0.0025kg
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How to find the number of atoms?
To find the number of atoms, we multiple the number of mols by Avogadro's number, about 6.02x10^23
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Answer:
to calculate the numbers of atoms in a sample, divide it's weight in grams by the amu atomic mass from the periodic table, then multiply the result by avogadro's number: 6.0 × 10^24
What is the ratio of aluminum atoms to oxygen atoms in aluminum oxide?
Answer:
Al2 O3 or 2:3
Explanation:
The aluminum oxide consists of two elements, which are oxygen atoms and aluminum atoms, and there are 2 aluminum atoms and 3 oxygen atoms in aluminum oxide. The ratio from aluminum atoms to oxygen atoms is 2:3.
There are two types of chemical compound one is covalent compound and other is ionic compound, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. Therefore, the ratio of aluminum atoms to oxygen atoms in aluminum oxide is 2:3.
What is chemical Compound?Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.
An ionic compound is a metal and nonmetal combined compound. Ionic compound are very hard. They have high melting and boiling point because of strong ion bond. The ratio of aluminum atoms to oxygen atoms in aluminum oxide is 2:3. Aluminium oxide is an ionic compound.
Therefore, the ratio of aluminum atoms to oxygen atoms in aluminum oxide is 2:3.
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What are some things that uses oxygen
Answer:
Common uses of oxygen include production of steel, plastics and textiles, brazing, welding and cutting of steels and other metals, rocket propellant, oxygen therapy, and life support systems in aircraft, submarines, spaceflight and diving.
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
Help this is not that hard I think
Answer:
1,) True
2.) False
3.) A Moraine
Explanation:
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Calculate the density of helium if a balloon with a capacity of 5.00 L holds 0.890 g.
Answer:
Explanation:
Density is m/V. Also, 1 liter = 1000 [tex]cm^3[/tex]. So, we get 0.890/(5*1000) = [tex]1.78*10^{-4}[/tex] g/cm^3. You can convert this to kg/m^3 as well by multiplying it by 10. Depends which one you want.
The ratio of the mass in grams and volume in cubic meters gives the density. The density of 0.80 gm helium is 1.78 × 10 ⁻⁴ g/cm³.
What is density?Density is the amount or the number of entities that can be contained in an area. It is denoted by ρ and is calculated as,
Given,
Mass = 0.890 gm
Volume = 5000 cm³
ρ = Mass ÷ Volume
= 0.890 ÷ 5000
= 1.78 × 10 ⁻⁴ g/cm³
Therefore, 1.78 × 10 ⁻⁴ g/cm³ is the density of helium.
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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
what this pic meaning ?
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The Statue of Liberty is made out of copper and was once shiny and copper-colored. Over the years, the copper has gone through a process called oxidation, where it has changed into a new material.
What has occurred?
an endothermic reaction
an energy formation
a chemical reaction
a precipitate formation
Answer:
an endothermic reaction
Explanation:
An endothermic reaction has occurred.
Answer:
endothermic
Explanation:
took the quiz
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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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
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
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
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.
which of the following is a state of matter ? particle,thermal,plasma, and diffuse ?
Answer:
a particle
Explanation:
matter takes up space, and particles take place in atoms
Answer:
plasma is a state of matter