Answer:
The reaction for which ΔH is positive are endothermic reactions. Explanation: The energy changes occur during the bonds formation and bonds breaking
7th grade help me plzzzzzzzz
Answer:
1. Metals
2. Solid, gas, liquid
Explanation:
For #1:
The majority of elements in the periodic table are classified as metals. The transition metals lie in the center of the table, spanning groups three through 12. These elements are solid at room temperature, except mercury, and have the metallic color and malleability expected of metals.
Hope this helps :)
what is S oxidation number
the answer to you question is -2
How much eat is absorbed when 50.0g of water changes from 25.0 Celsius to 37.0 Celsius?
What is the value of index fossils to the fossil record?
221 A grocery shop has different types of fruit: one box contains 10 mangos, another
contains 7 avocados and the third box contains 5 lemons.
The same shop has 20% organic food. 50% inorganic food, and 30% of the things they sell
are juices.
3 marks)
A) Represent the types of fruit in bar graph.
B) Represent the sales in pie graph.
Answer:
A) Please see the required bar graph attached
B) Please see the required pie graph attached
Explanation:
The given data are;
The number of each fruit in each box are;
First box contains 10 mangoes
Second box contains 7 avocados
Third box contains 5 lemons
The percentage of the things they sell are;
Organic food = 20%
Inorganic food = 50%
Juices = 30%
A) The bar graph is plotted with Microsoft Excel
The height of each column is equivalent to the number of fruit in the box
Each column represents a box of fruit
B) The pie graph (chart) is generated with Microsoft Excel
The steps to draw the pie chare are;
1) Draw a circle
2) Partition the circle into segments proportional to each percentage from the center of the circle as follows;
The sum of angles at the center of the circle = 360°
The angle of the segment that will represent the 20% organic food in the pie chart = 20/100 × 360° = 72°
Therefore, the segment representing organic food will have an angle of 72° at the center of the circle
Similarly, the segment representing inorganic food will have an angle of 50/100 × 360° = 180° at the center of the circle
The segment representing juices will have an angle of 30/100 × 360° = 108° at the center of the circle.
Isopentyl acetate is the molecule largely responsible for the aroma and taste of bananas. It is made up of carbon, hydrogen, and oxygen. Combustion of a 3.256-g sample of isopentyl acetate produces 7.706 g CO2 and 3.156 g H2O. Using these results, what is the correct empirical formula for isopentyl acetate?
Answer:
Explanation:
7.706 g of CO₂ will contain 12 x 7.706 / 44 g of C
= 2.1 g of C .
This will be contained in 3.256 g of isopentyl acetate
3.156 g of H₂O will contain 2 x 3.156 / 18 g of H
= .351 g of H
This will be contained in 3.256 g of isopentyl acetate
Rest will be oxygen
amount of oxygen in 3.256 g of isopentyl acetate
= 3.256 - ( 2.1 + .351 )
= .805 g
ratio of C , H , O in isopentyl acetate
= 2.1 g : .351 g : .805 g
2.1 / 12 : .351 / 1 : 0.805 / 16 ratio of moles
= .175 : .351 : .05 ratio of moles
= 3.5 : 7.02: 1
= 7 : 14 : 2
empirical formula of isopentyl acetate
= C₇ H₁₄ O₂ .
argon is an inert gas give reason.
Answer:
You're right
Argon is an inert gas.
Explanation:
Answer:
Argon is in zero group and it has octet structure so argon will not react with any compound
How can electronegativity be used to explain the reaction we see in terms of the numbers and types of bonded being formed in lithium?
Explanation:
Lithium is an electropositive element that readily loses electrons.
Oxygen is electronegative and it will readily accept electrons.
Due to this significant electronegativity differences between the two species they form electrovalent or ionic bonds between them.
2atoms of Li lose two electrons:
Li → Li²⁺ + e⁻
Lithium isoelectronic with helium
For oxygen;
O + 2e⁻ → O²⁻
Oxygen is isoelectronic with Neon
Two ions of the lithium combines with the oxygen to form the bond;
4Li + O₂ → 2Li₂O
The electrostatic attraction between the two ions forms the ionic bond
What is the formula for mass number?
Answer:
the formula for mass number is "mass number = protons + neutrons".
Why are supergiant so bright?
Because supergiants are so massive, the core temperature gets much hotter than in giants, so supergiants can fuse elements heavier than hydrogen and helium. But to support their tremendous mass, supergiants burn up their fuel much more quickly.
Answer:
because the core tempature gets much hotter.
Explanation:
so supergiants can fuse elements heavier than hydrogen and helium. But to support their tremendous mass, supergiants burn up their fuel much more quickly.
Which of the following atoms has the smallest atomic radius?
A. F
B. Li
C. C
D. Be
Answer:
A) F
It has the smallest atomic radius.
What is a rule for determining the mass number of an atom or ion?
Answer:
The mass number of the atom is equal to the sum of the number of protons and neutrons in the nucleus
Explanation:
Each proton and each neutron weigh one amu( atomic mass unit), adding together the neutrons and protons and multiplying by 1 amu you get the mass of an atom
Which of the following statements are incorrect?
A. A sodium atom has a smaller radius than a potassium atom.
B. A neon atom has a smaller radius than an oxygen atom.
C. A fluorine atom has a smaller first ionization energy than an oxygen atom.
D. All are statements are incorrect
b is the answer because oxyen atom has a smaller radius
Answer: B
Explanation:
Consider the equation:
Ca+O2→CaO
What needs to be done in order to balance the equation?
Place a 2 in front of the Ca and the CaO.
Place a 2 in front of the O2 and the CaO.
Place a 2 in front of the CaO only.
Place a 2 only in front of the Ca.
Lithium has two isotopes, lithium-6 weighing 6.015 amu (7.5% abundance), and lithium-7
weighing 7.016 amu (92.5% abundance). What is the atomic mass of lithium?
with calculations
Answer:
The answer is 6.941 but I dont really have the explanation
Explanation:
The atomic mass of lithium will be 6.9458 amu.
What is Atomic Mass ?
The mass of an atom of a chemical element expressed in atomic mass units.
It is approximately equivalent to the number of protons and neutrons in the atom (the mass number) or to the average number allowing for the relative abundances of different isotopes.
Calculation :
Consider 10000 atoms of Li ;
742 of them would have mass 6.02.9258 of them would have mass 7.02.
Hence,
The total mass of these 10000 Li atoms would be ;
(742 × 6.02) + (9258 × 7.02) = 69458
∴ 1 Li atom on average would have mass = 69458 / 10000 = 6.9458 amu
Therefore, The atomic mass of lithium will be 6.9458 amu.
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The ____ energy of an object increases with its height.
Thermal
Chemical potential
Gravitational Potential
kinetic
Answer:
chemichal potential
Explanation:
Answer:
Gravitational Potential
A divalent metal oxide contains 60 % of metal. What is atomic weight of metal ?
Atomic weight of metal : 24
Further explanationProust states the Comparative Law that compounds are formed from elements with the same Mass Comparison so that compounds have a fixed composition of elements
Divalent metal oxide=XO
MW O = 16
MW XO₂ = X+16
[tex]\tt \%mass=\dfrac{Ar~X}{X+16}\times 100\%\\\\0.6=\dfrac{X}{X+16}\\\\0.6(X+16)=X\\\\0.6X+9.6=X\\\\0.4X=9.6\rightarrow X=24[/tex]
I will pick the brainiest answer! Thanks! :)
1. What is volume displacement? Why would you use this method?
2. What is density? What happens to things that are denser? What happens if they are less dense?
Answer:
1. The volume of displaced fluid is equivalent to the volume of an object fully immersed in a fluid or to that fraction of the volume below the surface of an object partially submerged in a liquid. The weight of the displaced portion of the fluid is equivalent to the magnitude of the buoyant force.
Why would you use this method?
So it can be used to accurately measure the volume of the human body and other oddly shaped objects by measuring the volume of fluid displaced when the object is submerged.
2. Density, mass of a unit volume of a material substance. The formula for density is d = M/V, where d is density, M is mass, and V is volume. Density is commonly expressed in units of grams per cubic centimetre.
What happens to things that are denser?
Students should realize that if an object weighs more than an equal volume of water, it is more dense and will sink, and if it weighs less than an equal volume of water, it is less dense and will float.
What happens if they are less dense?
The density of an object determines whether it will float or sink in another substance. An object will float if it is less dense than the liquid it is placed in. An object will sink if it is more dense than the liquid it is placed in.
How are oxidation states of transition metals indicated in the names of metal
compounds?
A. Prefixes are used to indicate oxidation states.
B. Group numbers are used to indicate oxidation states.
C. Roman numerals are used to indicate oxidation states.
D. Subscripts are used to indicate oxidation states.
Answer:
The anser is c
Roman numerals are used to indicate oxidation states. Hence, option C is correct.
What is the oxidation state?An oxidation state is a number given to the atom of an element when participating in a chemical reaction.
Roman numerals are used to indicate oxidation states of transition metals.
The names for transition metal compounds often have roman numerals in them, because the roman numerals indicate the charge on the transition metal. But the oxidation state of Cu in CuO is +2, and the oxidation state of Cu in [tex]Cu_2O[/tex] is +1. Name metal first and charge and transition metal with a roman numeral.
The transition metals may form more than one ion, thus it is needed to be specified which particular ion we are talking about. This is indicated by assigning a Roman numeral after the metal. The Roman numeral denotes the charge and the oxidation state of the transition metal ion.
[tex]Fe^{2+}[/tex] would be named iron (II) and [tex]Fe^{3+}[/tex] would be named iron (III).
Hence, option C is correct.
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How many number of oxygen molecules are required to produce 0.22 g of CO2 according to the reaction?
c+o2=co2
The first noble gas with a Lewis Structure with 8 dots is
A. Ar
B. Kr
C. He
D. ne
Answer:
C) He
Explanation:
Helium is one of the noble gases and contains a full valence shell. Unlike the other noble gases in Group 8, Helium only contains two valence electrons.
How do slab pull forces affect plate motion? Choose the correct answer.
Uplifted mantle causes plates to move apart.
Convection currents drive the plate downward to move it.
Earthquakes break the crust into smaller plates to make motion easier.
The weight of the subducted plate produces a force to continue moving the plate.
Answer:
The weight of the subducted plate produces a force to continue moving the plate.
Explanation:
To pass a test with 15 questions how many can I get wrong?
Answer:
You can get 7 answers wrong.
Explanation:
Let's calculate the average
[tex]\frac{15}{2} \\\\=7.5[/tex]
So if you correctly answer 8 -15 (7.5 is approximated to 8 )questions correctly you will pass.
So you can get 7 answers wrong.
Emma draws a sketch of what happens to light as it moves through air and then into a tank of water. describe what happens to the speed of light as it enter the water.
Answer if you know, if you don't move on please! If you don't know comment not answer. Thank you!!
Answer:
The speed of light becomes slower in denser medium which is water in this case.
Explanation:
We know the lens law of Refraction which states
[tex]\frac{Sin(i)}{Sin(r)} =[/tex] Refractive index of second medium /Refractive index of the first medium
= Velocity of light in medium 1 (V1)/ velocity of light in medium 2 (V2)
When light rays fall from air medium into water which is a denser medium bending of light or change in the direction of light occurs which is knows as Refraction.
When refraction occurs speed of the light rays are also varied as we can see it from the Lenz's Law. suppose two light rays parallel to each other falling on the air-water interface at an angle , the first ray will reach the interface and bend about the normal and then the second ray. We also observe when light enters denser medium the speed of light becomes slower, also the bending of light when going from rarer to denser it bends towards normal of the surface and when it move from denser to rarer medium it moves away from the normal to the surface.
Using dimensional analysis, how many kilometers are there in 34 inches?
Answer:
There are many ways to figuring this out: you could use a ruler, a calculator or scrap paper.
Explanation:
This is not an actual flat out answer, but it’s helpful methods to getting the answer the next time you are stuck. Hope you are having a nice day. Bless your heart and soul.
What part of the earth are the plate tectonics on?
lithosphere
outer core
asthenosphere
inner core
Help! I am in a hurry! Will get brainliest if correct!
Answer:
nonmetel
Explanation:
Answer:
Its a non-metal
Explanation:
Elements that tend to gain electrons to form anions during chemical reactions are called non-metals. These are electronegative elements. They are non-lustrous, brittle and poor conductors of heat and electricity (except graphite). Non-metals can be gaseous, liquids or solids.
Examine the layers of rock. How does layering provide evidence for determining geologic age?
Answer:
the deeper you go down in to the rock the older the fossils get.
Explanation:
layering can provide evidence because the deeper you go down in to the rock the older the fossils get. So when the scientists go in to the rock they can say what animals lived in that time and what animal was the oldest.
The element magnesium is a
O Group 12, Transition Metal
O Period 3, Alkaline Earth Metal
Period 4. Alkali Metal
O Period 4, Halogen
If 0.484J of heat is added to 0.1372g of water, how much will the temperature increase?
0.263 °C
0.927 °c
0.843 °C
0.460 °C
Answer:
ΔT = 0.843 °C
Explanation:
Given data:
Heat added = 0.484 J
Mass of water = 0.1372 g
Temperature increase = ΔT = ?
Solution:
Formula:
Q = m.c. ΔT
Q = amount of heat absorbed or released
m = mass of given substance
c = specific heat capacity of substance
ΔT = change in temperature
Specific heat capacity of water is 4.184 j/g.°C
Now we will put the values in formula.
0.484 j = 0.1372 g × 4.184 j/g.°C× ΔT
0.484 j = 0.574j/°C× ΔT
ΔT = 0.484 j / 0.574j/°C
ΔT = 0.843 °C