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
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
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 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
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
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
I WILL GIVE YOU BRAINLIEST!!!
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 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
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.
Which of the following elements would be brittle?
Sulfur
Magnesium
Rubidium
Lithium
Answer:
Sulfur
Explanation:
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 :) *
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
what this pic meaning ?
What do these two changes have in common?
an old sandwich rotting in a trashcan
and baking cookies
please hurry asap I WILL MARK BRAINLEST
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
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!
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 penny is 2.5 g. How many kilograms does a penny weigh?
Answer:
The penny now weighs 0.0025kg
Hope this helps please give me brainliest!
God bless!
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:
Have A Wonderful Day !!
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
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.
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.
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]
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
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Answer:
This shoes the soda lime defusing to limewater turning into germinating seeding which defuses back to limewater
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.
Learn more about energy level,here:
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is Mo2S6 ionic or covalent
Answer: Ionic
Explanation:
Answer:
ionic
Explanation:
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.
Learn more about isotopes here:
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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)