Answer:
A chemical change happens when one chemical substance is transformed into one or more different substances, such as when iron becomes rust.
Explanation:
Answer: when one chemical substance is transformed into one or more different substances.
Explanation:
A student has a sample of solid calcium. It is shiny and metallic looking. He squeezes a pipet of concentrated sulfuric acid onto the calcium. Bubbles are produced and the calcium appears to disappear. The test tube gets hot. What kind of change occurred?
Answer:
Physical change
Explanation:
There are two types of changes: physical change and chemical change. Physical change is defined as the change that changes the physical appearance of the substance and do not affcet the chemical composition of the substance whereas chemical change causes changes in the chemical composition of the susbstance.
The given example shows physical change because solid calcium undergoes sublimation. process in which a solid substance changes into gaseous phase directly without undergoing liquid phase.
Hence, the correct answer is "Physical change".
during chemical reaction do atoms change into a new substance
true or false
Answer:
t
Explanation:
because for atoms to change they have to have some kind of chemical action to get new life
Please answer correctly !!!!!!!!!!!!!!!!! Will mark brainliest !!!!!!!!!!!!!!!! And explain please !!!!!!!!!!!!
Hope this is your answer i wasn't able to see he full question so i am not sure
Why is hydrogen peroxide sold in opaque plastic bottles?
it's not a very stable compound
How many grams are in 1.98 x 1024 formula units of NaCl?
Answer:
There are 2027.52 formula units of NaCl
Explanation:
plz mark me brainlest
Using the em figure what color is the wavelength 436 nm
Answer:
Blue
Explanation:
Explain what intermolecular forces are, and how they are easily overcome.
Explanation:
Intermolecular forces are forces that exist between two or more molecules and they can be overcome at high temperatures.
Between Na and Na+ which has larger size
Answer:
Na+ is smaller than Na because, it has given away one electron because of which the electron shielding gets stronger due to more protons and less electrons. Whereas, Cl- is larger than Cl because it has gained an extra electron and so, the no.07/12/2010
Explanation:
which of the following molecules has only two non binding pairs (long pairs) of electrons in its lewis structure?
a)O2
b)CH4
c)NH3
d)H2s
Explanation:
NH₃ has only two non-binding pairs (lone pairs) of e⁻ in it's Lewis structure.
••
H—N—H
|
H
Therefore,
C is correct. ✔
Why the noble gases are found in small amounts in the earth's atmosphere?
Answer:
They have completely filled outermost shell
Explanation:
The noble gases are the rarest and occur in trace amounts in the atmosphere because they have completely filled outermost and this makes them unreactive with other elements.
Elements become abundant as they combine with other species to form compounds.
Noble gases on the other hand have a high level of stability and do not readily combine with other species.
Some of these gases are :
Helium
Neon
Argon
Krypton
Xenon
Radon
They have very high ionization energy and very low electron affinity and so will not readily react.
The capability of a substance to be stretched into thin wires without breaking is known as —
A malleability
B conductivity
C luster
D ductility
Answer:
The answer is D, ductility
Explanation:
The definition of ductile is "(of a metal) able to be drawn out into a thin wire."
Is the following an element, compound, homogeneous mixture, or heterogeneous mixture?
Coca-cola
Answer:
CO2 is classified as a compound
Explanation:
A hypothesis is ______ to explain a set of observations.
1 one possible way
2 the correct method
3 a factual statement
4 a set of data
Answer:
1
Explanation:
one possible way its just a theory of what the answer could be
Answer:
3-a factual statement
Explanation:
A hypothesis is a factual statement to explain a set of observations.
The main goal of science is to
Answer:
The goal of science is to learn how nature works by observing the natural and physical world, and to understand this world through research and experimentation.
Explanation:
It is found that after 24!hours 1/8 of the mass of a sample of a radio-active isotope remains What is the half-life of this isotope?
Answer:7.72 years
Nuclear half-life expresses the time required for half of a sample to undergo radioactive decay.
Explanation:
0.01 = 67.0 ×[tex](\frac{1}{2}) ^{\frac{98.0} {1/2 } }[/tex] [tex]\frac{0.01}{67.0}[/tex] = 0.000149=[tex](\frac{1}{2}) ^{\frac{98.0} {1/2 } }[/tex]
[tex]^{\frac{98.0} {1/2 } }[/tex] =log[tex]_{0.5}[/tex] (0.000149)=12.7
[tex]^{\frac{98.0} {1/2 } }[/tex]=7.72 years
Hope this helps have a great day/afternoon :)
19. Who was the first female astronomer
A.Aristotle
B.En Hedu’Anna
C.Archimedes
D.Plato
Answer: A.En Hedu'Anna
Answer:
En Hedu’Anna!
Explanation:
What type of reaction is the equation 2NaCl → 2Na +Cl2?
Answer:
Synthesis reaction
Explanation:
This is a synthesis reaction. When you combine sodium metal (Na) with chlorine gas (Cl), you form sodium chloride or kosher salt (NaCl).
Hope this explanation helps!
PLEASE ANSWER
A train travels 200 miles at an average speed of 50 miles per hour. How long does it take the train to travel this distance?
5. an atom that has lost or gained an electron and has become charged
A.ion
B. proton
C. ionic bond
D. compound
Answer:
It would be compound.
Explanation:
It is this way because if it adds another proton it becomes more positive that nuetral, and if you add an electron it just makes the atom more dense. That is why the answer is compound. Hope this helped :)
The maximum amount of statie friction between this chair
and the floor is 175 N.
Which action would cause the chair to move to the left?
A. Applying 100 N of force to the chair from the left
B. Applying 200 N of force to the chair from the left
O c. Applying 200 N of force to the chair from the right
O D. Applying 100 N of force to the chair from the right
Answer:
C
Explanation:
A p ex
Which particle changes to create a positive or negative ion of an atom?
A.proton
B. neutron
C. electron
Answer:
it is alkali
Explanation:
hope it helps you
Explain why you cannot use a pump like the one at the right to
lift water up to the 3rd floor of an apartment building.
Answer:
can you aks it more clerlry
Explanation:
Snakes and similar animals are members of a group called reptiles.
How do reptiles differ from other animals?
Answer:
They have skin covered with scales.
TIME REMAINING
58:36
The electron configuration for Helium (He) is shown below.
1s2
Which diagram shows the correct distribution of electrons in the electron shells of a helium atom?
Answer:
'*:*'
Explanation:
I know this looks weird, but
'= electron
*:* equals the nucleus, so 2 protons and 2 neutrons
and then '=electron
8. What is Planck's law?
O F = hm
O F = MA
O E = hf
O E = mc (squared)
Answer:
O E = hf
Explanation:
why is diamond said to be hard
Answer: Diamond is said to be the hardest element because it is unbreakable by humans. These diamonds are mined, and they are very hard. A miner knows when they have found diamond when they feel something super hard.
Hope this helps you!
Is the freezing point of this 5??
Please correct my mistake if it isn't.
Answer:
yes
Explanation:
Answer:
yes
Explanation:
you're smart have a nice evening
Wear lightweight clothes in the_____. not sun or summer and is it heat
Answer:
there was too much heat
Explanation:
what acts as a buffer for seawater ?
Answer:
The bicarbonate and carbonate ions.
Explanation:
Probably not he answer your looking for though. So, CO2.
12. A 100.00-gram sample of naturally occurring boron
contains 19.78 grams of boron-10 (atomic mass =
10.01 atomic mass units) and 80.22 grams of
boron-11 (atomic mass = 11.01 atomic mass units).
Which numerical setup can be used to determine the
atomic mass of naturally occurring boron?
A) (0.1978)(10.01) + (0.8022)(11.01)
B) (0.8022)(10.01) + (0.1978)(11.01)
C) (0.1978)(10.01)/(0.8022)(11.01)
D) (0.8022)(10.01)/(0.1978)(11.01)
It’s A) (0.1978)(10.01) + (0.8022)(11.01)
Relative and average atomic mass both describe properties of an element related to its different isotopes. Out of these two Relative atomic mas is more accurate. Therefore option A is correct option.
What is mass?Mass defines the quantity of a substance. It is measured in gram or kilogram. Average mass is the mass of atoms of an element that are isotopes. It can be calculated by multiplying mass of a isotope to natural abundance of that isotope.
Mathematically,
average atomic mass= ∑(relative abundance x mass of isotope)
average atomic mass boron= (relative abundance boron-10 x mass of isotope boron-10)+(relative abundance boron-11 x mass of isotope boron-11 )
average atomic mass boron=(0.1978)(10.01) + (0.8022)(11.01)
Therefore option A is correct option.
To learn more about mass, here:
https://brainly.com/question/28704035
#SPJ2