Answer:
21%
Explanation:
It's a mixture of different gases. The air in Earth's atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen.
What does aqueous mean in a chemical equation?
Answer: a solution where the solvent is water
Explanation: solute ions which are known as the dissolvable ions and molecules are surrounded by water molecules and then get incorporated into the bonding network of water
1 poin
9. In an experiment, the one variable that is changed on purpose by the
scientist is called the
controlled variable
experimental variable
independent variable
dependent variable
Answer:
It's called Independent variable
Explanation:
....
Drag the tiles to the correct boxes to complete the pairs.
Chromium is a transition metal, and oxygen has an oxidation number of -2. Use this information to match each compound to its chemical formula.
Julie finds a snail on the sidewalk and wants to know whether or not the snail moves throughout the day. She places a single mark on the sidewalk next to the snail.
What will Julie use the mark for initially?
determining how fast the snail moves
acting as a standard unit of measure
determining the displacement of the snail
acting as a reference point for detecting motion
Answer:
b-acting as a standard unit of measure
Explanation:
Julie uses the mark for initially acting as a standard unit of measure. The correct option is b.
What is observation?Recognizing and writing down an occurrence or fact is the process of observation, which frequently entails measuring it with tools. Utilizing tools for measurement is frequently required when recognizing and documenting an occurrence or fact. Written observations taken during or right after fieldwork are referred to as field notes.
They are essential for comprehending occurrences observed in the field. Scratch notes, diaries, and notebooks are common formats for field notes. The process of observation is essential in science. Snails are the molluscan. It comes under zoological study.
Therefore, the correct option is b. acting as a standard unit of measure
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Identify the correctly written chemical reaction.
A. Reactant + Product → Reactant + Product
B. Product + Product → Reactant + Reactant
C. Reactant + Reactant = Product
O
D. Reactant + Reactant → Product + Product
Answer:
eek um A.The substance(s) to the left of the arrow in a chemical equation are called reactants. The substance(s) to the right of the arrow is called products.
Explanation:
Can someone please help me answer these Questions pleaseee
How many moles of MgCO3 are in 2.57g of MgCO3?
Answer:
0.0305 moles of MgCO₃
Explanation:
In order to solve this problem, we first need to calculate the molecular weight of MgCO₃:
MgCO₃ MW = Atomic mass Mg + Atomic mass C + (Atomic mass O)*3MgCO₃ MW = 24.3 + 12 + 16*3 = 84.3 g/molFinally we divide the mass by the molecular weight, to calculate the number of moles:
2.57 g MgCO₃ ÷ 84.3 g/mol = 0.0305 moles.What causes fireworks
Answer:
Explanation:
A
potential
1
Fill in the blanks to complete the sentences.
food
Energy is the ability to do
work
which is what makes
matter
move or change.
physical
kinetic
Objects at rest have stored
energy, while objects in motion
have
energy
In order to exercise and do other
activities, our bodies need
the chemical energy stored in
HELPPPPP
Answer:
work
matter
potentioal
kinetic
physical
food
Explanation:it is in the order above ^
Which of the following are properties of ionic compounds?
A. hard solids with high melting and boiling points.
B. soft and good conductors of electricity.
C. both A and B
D. good conductors of electricity, but only when dissolved in water
Answer:a and d
Explanation:
The properties of ionic compounds are hard solids with high melting and boiling points and good conductors of electricity, but only when dissolved in water and the correct options are option A and D.
What are Ionic solids?Ionic solids are made up of ions joined together by ionic bonds. "Ionic bonding" is a type of chemical bond between a positive and a negatively charged ion where the transfer of electrons occurs.
They are too hard, and the ionic solids’ melting point is usually too high due to powerful forces between the anions and cations.
They are known as electrical insulators when they are in a solid-state. Apart from this, the molten salts do behave with electricity since the ions are not closed in the lattice.
Therefore, the properties of ionic compounds are hard solids with high melting and boiling points and good conductors of electricity, but only when dissolved in water and the correct options are option A and D.
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(Gr.7science)
Can somebody plz help answer both these questions only in 1-2 sentences if u can thanks! :D
WILL MARK BRAINLIEST..promise
Answer:Crystalline solids have well-defined edges and faces, diffract x-rays, and tend to have sharp melting points. In contrast, amorphous solids have irregular or curved surfaces, do not give well-resolved x-ray diffraction patterns, and melt over a wide range of temperatures.
Explanation:
Answer:
:-::-::
Explanation:
Determine whether each statement is an example of a physical change or a chemical change. Paper is shredded. physical chemical
Answer:
That would be a physical change
Explanation:
A physical change is when you are changing the physical properties of something but not changing its overall identity and a chemical change is when yo are changing the physical properties and changing its identity .
Ex. Ripping a dollar bill- Physical change
Burning a dollar bill- chemical change
Answer:
first one is physical , second one is chemical
Explanation:
Consider the Mg2+, Cl-, K+, and Se2- ions.The four spheres below represent these four ions, scaled according to ionic size. A) Match each ion to its appropriate sphere. B) In terms of size, between which of the spheres would yo find the (i) Ca2+ and (ii) S2- ions?
Answer:
A is Mg^2+
B is K^+
C is Se^2-
D is Cl^-
Ca^2+ lies between Mg^2+ and K^+
S^2- lies between K^+ and Se^2-
Explanation:
I have attached an image of the four spheres.
Remember that, cations are smaller in size than the corresponding atom atom because the formation of a cation often involves the removal of an entire shell. Anions are larger in size than the corresponding atom because an electron is added thereby expanding the electron cloud and size of the anion.
From left to right let us designate the spheres as ABCD.
A is Mg^2+
B is K^+
C is Se^2-
D is Cl^-
Ca^2+ lies between Mg^2+ and K^+
S^2- lies between K^+ and Se^2-
The size of the spheres, going from smallest to largest, would be: [tex]Mg^2^+[/tex], [tex]K^+[/tex], [tex]Ca^2^+[/tex], [tex]Cl^-[/tex], [tex]S^2^-[/tex], [tex]Se^2^+[/tex].
We can arrive at this answer because:
To know the size of the spheres of an ion, we must know if they are a cation or an anion and the number of electrons in each valence layer that is gained or donated.Cations are the ions that donate electrons. They are represented by the + symbol and get smaller and smaller as they donate electrons.Therefore, we can state that the cations [tex]Mg^2^+[/tex], [tex]K^+[/tex], [tex]Ca^2^+[/tex] have the smallest spheres.On the other hand, anions, represented by the - symbol , have the largest spheres because they receive electrons.In this case, the [tex]Cl^-[/tex], [tex]S^2^-[/tex], [tex]Se^2^-[/tex] anions have the largest spheres.This is because when donating electrons, the cations get the largest number of protons. This makes the cation nucleus attract the electronic layers, decreasing their extension. In anion, the opposite happens and the increase of electrons increases the extension of the electronic layers.
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Identify the labeled structures.
A:
B:
C:
D:
E:
cell membrane
Golgi body
mitochondrion
nucleus
vacuole
Explanation:
A = Golgi body
B = Vacuole
C = Mitochondrion
D = Nucleus
E = Cell membrane
Answer:
A = Golgi body
B = Vacuole
C = Mitochondrion
D = Nucleus
E = Cell membrane
Explanation:
give credit to the other person they helped me
too have a good day :)
4. The heat of
fusion of a
substance is
80 J/g. How
much energy
is required to
melt 25 g of
the
substance?
A. 2J
B. 25 J
C. 80 J
D. 2 kJ
It is 2 KJ
It is because the formula is :
q=m∆Hf
where m is the mass and ∆Hf is the heat fusion.
So, we get:
q=80×25
q=2000J or 2 KJ
Nitrogen changes from a liquid to a gas at the same temperature at
which water changes from a liquid to a gas.
True or false
Answer:
False
Explanation:
if this were true then water would not be available on earth other than in the atmosphere because of evaporation
Why is Bohr diagram better than orbital diagram ?
Answer:
hfjdjdjdjdjdjdjd
Explanation:
rjeiejejejeje
2.4 Propene reacts with steam to produce an alcohol, propanol.
Complete the equation for the reaction.
C3H6 + H2O
Answer:
C₃H₆ + H₂O = C₃H₈O
Explanation:
Hydration reactions (reactions involving converting an alkene to alcohol) have only one product, so there will be no byproduct along with propanol.
Propene reacts with steam to produce propan-2-ol. The reaction is C₃H₆ +H₂O[tex]\rightarrow[/tex]C₃H₈O. It is an example of hydration reaction.
What are hydration reactions?Hydration reaction is defined as a chemical reaction wherein a substance combines with water. In organic chemistry, when an unsaturated substance reacts with water it is called as hydration reactions.
The reaction involves breaking of hydroxyl bond in water which is highly exothermic releasing large amount of energy. Direct addition of water to an alkene is too slow and hence the rate is catalyzed by Lewis acids or Bronsted acids.
Hydration reactions are extensively used for industrial production of butanol and isopropanol,etc.The addition of water along the double bond in alkenes takes place according to Markovnikov's rule.
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Hello can someone help me out i will give brainliest. Its chemical or physical hw
Answer:
16- physical
14- chemical
15- chemical
13- physical
Explanation:
A chemical change would be something like the burning of wood, it's an object changing into something new, or something changing. A physical change would just basically altering something like bending wood, it's still wood whether or not you bend it.
Bridget performed an investigation to determine if a television set transformed electrical energy into other types of energy. She recorded her observations in a table.
What statement best describes the results?
Question Observation
Does it transform into heat energy? Yes
Does it transform into light energy? Yes
Does it transform into sound energy? Yes
Does it transform into energy of motion? No
1 A television transforms electrical energy into heat and light energy.
2 Electrical energy transforms into more than one type of energy.
3 Sound energy is transformed from heat and light energy.
4 You can transform electrical energy into energy of motion.
all my points if u answer themmm
Answer:
2 ;)
Explanation:
1
Complete and balance the following equations : Al + NaOH +___--->_____+____
Answer:
Al + 3NaOH = Al(OH)₃ +3Na
Explanation:
The reaction is given as:
Al + NaOH = Al(OH)₃ + Na
This reaction is called a single displacement reaction in which one specie displaces another from a solution.
To balance the equation:
aAl + bNaOH = cAl(OH)₃ + dNa
a, b, c and d are the coefficient that will balance the equation:
Conserving Al;
a = c
Conserving Na;
b = d
Conserving O;
b = 3c
Conserving H;
b = 3c
Let a = 1, c = 1, b = 3 and d = 3
Al + 3NaOH = Al(OH)₃ +3Na
Calculate the mass of one mole of these substances.
a. NH4Cl
b. NH4NO3
c. AlCl3
Helppp plss :)
Answer:
a. 53.5 g/mol
b. 80.06 g/mol
c. 133.33 g/mol
General Formulas and Concepts:
Chemistry - Atomic Structure
Reading a Periodic TableMolar Mass - 1 mol per x grams substanceExplanation:
Step 1: Define
a. NH₄Cl
b. NH₄NO₃
c. AlCl₃
Step 2: Find masses
Molar Mass of N - 14.01 g/mol
Molar Mass of H - 1.01 g/mol
Molar Mass of O - 16.00 g/mol
Molar Mass of Al - 26.98 g/mol
Molar Mass of Cl - 35.45 g/mol
Step 3: Calculate compound masses
Molar Mass of NH₄Cl - 14.01 g/mol + 4(1.01 g/mol) + 35.45 g/mol = 53.5 g/mol
Molar Mass of NH₄NO₃ - 2(14.01 g/mol) + 4(1.01 g/mol) + 3(16.00 g/mol) = 80.06 g/mol
Molar Mass of AlCl₃ - 26.98 g/mol + 3(35.45 g/mol) = 133.33 g/mol
Instructions: complete and balance the chemical equations for each chemical reaction in the virtual lab activity.
1. Combine iron and copper (II) sulfate solution. (Hint: Iron will form the iron (III) ion)
Fe + CuSO4 →
2. Combine lead (II) nitrate and potassium iodide solutions.
Pb(NO3)2+ Kl →
3. Combine magnesium metal and hydrochloric acid solution.
Mg + HCl →
4. Electrolysis (splitting) of water.
H2O →
5. Burning magnesium.
Mg + O2 →
Answer:
1. Combine iron and copper (II) sulfate solution. (Hint: Iron will form the iron (III) ion)
Fe + CuSO4 → FeSO4 + Cu
2. Combine lead (II) nitrate and potassium iodide solutions.
Pb(NO3)2+ Kl → Pbl2 + 2KNO3
3. Combine magnesium metal and hydrochloric acid solution.
Mg + HCl → MgCl2 + H2
4. Electrolysis (splitting) of water.
H2O → 2H2 + O2
5. Burning magnesium.
Mg + O2 → Mg2+O2-
Explanation:
How many grams are in 9.30 x 10-2 moles of calcium phosphate, Caz(PO3)2?
a. 25.9 g b. 17.65 g
c. 0.064 g
d. 259 g
Answer:
25.9 g
Explanation:
Given that,
No of moles of calcium phosphate, [tex]n=9.3\times 10^{-2}[/tex]
We need to find how many grams of calcium phosphate has this much of no of moles.
Mass divided by molar mass is equal to the no of moles on a molecule.
The molar mass of calcium phosphate is 310.18 g/mol
Using the concept of no of moles as follows :
[tex]n=\dfrac{m}{M}\\\\m=n\times M\\\\m=9.3\times 10^{-2}\times 310.18\\\\m=28.84\ g[/tex]
Out of given options, option (a) i.e. 25.9 g is the correct answer.
Free Brainly !! What is the cation and its' charge for the following compound?
CaCl2
Answer:
calcium cation
Formula and structure: The chemical formula of calcium chloride is CaCl2, and its molar mass is 110.983 g/mol. It is an ionic compound consisting of the calcium cation (Ca2+) and two chlorine anions (Cl-).
Explanation:
For what is the Endocrine system responsible for?
I will report your answer If its just to get points
A: Breathing.
B: Maintaining Homostasis.
C: Ridding of waste.
D: Protecting from Invaders.
Answer:
B: Maintaining Homostasis
Explanation:
Oxidation is the process by which _______.
A. an atom gains electrons
B. an atom loses electrons
C. negative ions are attracted to the anode
D. positive ions are attracted to the anode.
E. positive ions are attracted to the cathode.
Which formula shows the proper use of parentheses?
Ca(F)2
Ca(SO)
O (NH4)3 (PO4)
Ca(NO3)2
Answer:
This one here shows the proper use of parentheses>>>Ca(NO3)2
Calculate the pH of 0.02 M methanoic acid where Ka = 1.6 x 10^-4 M.
Answer:
pH = 2.75
Explanation:
Methanoic acid, HCOOH, is in acidic equilibrium:
HCOOH ⇄ HCOO⁻ + H⁺
And Ka is defined as:
Ka = 1.6x10⁻⁴ = [HCOO⁻] [H⁺] / [HCOOH]
As both HCOO⁻ and H⁺ ions comes from the same equilibrium, we can solve these concentrations assuming the HCOOH produce X of both HCOO⁻ and H⁺ ions:
1.6x10⁻⁴ = [HCOO⁻] [H⁺] / [HCOOH]
1.6x10⁻⁴ = [X] [X] / [0.02M]
3.2x10⁻⁶ = X²
X = 1.79x10⁻³M = [H⁺]
As pH = -log [H⁺]
pH = 2.75The pH of the 0.02 M methanoic acid is 2.75 acid when the dissociation constant is [tex]1.6 \times 10^{-4} \rm \ M.[/tex]
At equilibrium, the dissociation of Methanoic acid,
HCOOH ⇄ HCOO⁻ + H⁺
In the reaction, Methanoic acid dissociates to form HCOO⁻ and H⁺. So, the concentration of both products will be equal.
pH can be calculated by using Ka,
[tex]\bold{Ka = \dfrac {[HCOO^-] [H^+] }{[HCOOH]}}[/tex]
Where,
Ka - dissociation constant = 1.6x10⁻⁴
[HCOOH ] - concentration of Methanoic acid = 0.02 M
[tex]\bold{1.6 \times 10^{-4} M.= \dfrac {[HCOO^-] [H^+] }{[HCOOH]}}[/tex]
Let the concentration of each product is [tex]x[/tex]
So,
[tex]\bold{1.6 \times 10^{-4} \ M}= \dfrac {[x] [x] }{[0.02]}}\\x^2 = 3.2\times 10^{-6}\\x = 1.79\times 10^{-3}\rm \ M[/tex]
Put the value in the pH formula,
[tex]\bold {pH = - log [H^+]}\\\\\bold {pH =- log \ 1.79\times 10^{-3}\rm \ M}\\\\\bold {pH = 2.75 }[/tex]
Therefore, The pH of the 0.02 M methanoic acid is 2.75 acid when the dissociation constant is [tex]1.6 \times 10^{-4} \rm \ M.[/tex]
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Para un sistema, el valor de la constante que resulta del cociente entre el producto de la presión y el volumen con la temperatura es de 0,03 (atmxL/K). ¿cuál debe ser el valor de la temperatura del sistema para el volumen y la presión tengan valores 4500mL y 4,5atm?
Answer:
675 K
Explanation:
[tex]\dfrac{P_1V_1}{T_1}=0.03\ \text{atm L/K}[/tex]
Presión del sistema 2 = [tex]P_2=4.5\ \text{atm}[/tex]
Volumen del sistema 2 = [tex]V_2=4500\ \text{mL}=4.5\ \text{L}[/tex]
De la ley de los gases ideales tenemos la relación
[tex]\dfrac{P_1V_1}{T_1}=\dfrac{P_2V_2}{T_2}\\\Rightarrow 0.03=\dfrac{4.5\times 4.5}{T_2}\\\Rightarrow T_2=\dfrac{4.5\times 4.5}{0.03}\\\Rightarrow T_2=675\ \text{K}[/tex]
La temperatura del sistema para el segundo sistema es 675 K.