Explanation:
21 % of oxygen is present in air .
hope it is helpful to you
How many grams are there in 2.5 moles of Ca(OH)2?
Answer: 185 grams
Explanation: First find out how many grams are in one mol: The molar mass es are taken from the periodic table, Ca is 40, O is 16, H is 1. There are 2 O and 2 H for (OH)2: 40+32+2= 74g/mol x 2.5 mol = 185 the moles cancel and you are left with grams
Oxygen has a very low boiling point and is a gas at room temperature. Water has a much higher boiling point and is a liquid at room
temperature. Which of these statements would support these facts?
A)
Oxygen is an element while water is a compound.
B)
Oxygen is diatomic and exist as O2 in nature.
Water has a higher attraction between its molecules than oxygen.
D)
Water is a molecule with 3 atoms and oxygen exists in groups of 2.
Answer is C
3. If all of the predators in an ecosystem are killed off,
what happens to organisms that are their food source?
Answer:
its a little bit long but= The most obvious result of the removal of the top predators in an ecosystem is a population explosion in the prey species.More predators kill more prey, which, along with food scarcity, decreases the population. When prey becomes more scarce, the predator population declines until prey is again more abundant.
What is a galvanic cell made of
Answer: A galvanic cell consists of two different metals (electrodes) connected through a conducting solution (an electrolyte) and also connected externally completing a circuit.
name 3 common acids that you use in your home
Answer:
vinegar, soft drinks, seltzer water , citrus fruits
Explanation:
(10 POINTS!!!!!!!!!!!
What environmental change will take place when harmful substances get into the food and water supply of animals or plants?
A Climate change
B Increased predators
C Lack of food
D Pollution
need asap
Answer:
A climate change
Explanation:
the surrounding area would be effected in all ways imaginable, such as change in air, soil, water, plants, animals. and if you eat those said animals those harmful things can transfur into you
NEED ANSWER FAST !!
Using the following equation,
a. Balance the equation by putting the smallest whole number coefficient in each blank
Fe2O3 + H2 à Fe + H2O
b. Use the balanced equation to calculate how many grams of iron can be made from 0.025 mol of Fe2O3
Answer: grams Fe (Round your answer to the nearest hundreths)
Answer:
.-.
Explanation:
When the head of a match burns, chemical reaction is taking place. But a certain amount of energy is required to get this reaction started. This is the reactions activation energy. Describe where this energy comes from. What provides this energy?
Answer:
Rubbing the match against a rough surface
The activation energy is provided by friction between surfaces
Explanation:
Activation energy is the energy required to start a chemical reaction. It is the minimum energy that must be supplied for a reaction to proceed.
When we strike a match against a rough surface, what we are trying to do is to supply the required activation energy in the form of friction in order to get the combustion reaction started.
Hence, the activation energy for the combustion of a match head is supplied by friction when the match head is struck against a rough surface.
Which physical change is endothermic?
A.
CO2(g) → CO2(ℓ)
B.
CO2(g) → CO2(s)
C.
CO2(ℓ) → CO2(s)
Answer:
The correct answer is A
Explanation:
Endothermic is a reaction of which heat is provided to break down the reacted molecules
Which energy source is considered nonrenewable?
1) moving water
2) fossil fuel
3) wind
4) biomass
Answer:
Fossil fuel
Explanation:
Answer:
2
Explanation:
Nonrenewable energy resources include coal, natural gas, oil, and nuclear energy. Once these resources are used up, they cannot be replaced, which is a major problem for humanity as we are currently dependent on them to supply most of our energy needs.
Which statement describes copper?
O A. Copper is an insulator because its valence electrons can move freely from atom to atom.
O B. Copper is a conductor because its valence electrons can move freely from atom to atom.
O C. Copper is an insulator because its innermost electrons are shared between atoms.
O D. Copper is a conductor because its innermost electrons are shared between atoms.
Copper is a conductor because its valence electron can move freely from atom to atom. Option (B) is correct answer.
What is Insulator ?
Insulator is a material which does not conduct any current. Non metals are insulators. Electrons do not move freely in insulator. Thermal conductivity of insulator very is low and its resistance is vey high. These are used in making insulating electrical equipment.
What is Conductor ?Conductor is a substance which allow the electricity to flow through it. Metals are conductors. Electron can move freely in conductors. Thermal conductivity of conductor is very high and its resistance is vey low. These are used in making the electrical equipment.
Now let check all options one by one:
Option (A): Copper is a conductor not an insulator. Copper is a metal and it consists free electrons and electron can move freely from one atom to another atom.
So, option (A) is incorrect.
Option(B): Copper is a conductor because its valence electron can move freely from atom to atom. As copper is a metal it is a good conductor of electricity. The thermal and electrical conductivity of copper is high.
So, option (B) is correct.
Option (C): Copper is not an insulator it is conductor as already discussed in option (A).
So, option (C) is also incorrect.
Option (D): Copper is a conductor because its electron can move freely and it is a good thermal conductor.
So, option (D) is also incorrect.
Thus, from above conclusion we can say that Copper is a conductor because its valence electron can move freely from atom to atom.
Hence, option (B) is correct answer.
Learn more about Conductor and Insulator here: https://brainly.com/question/492289
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A HgO → Hg + O2
B 2Fe + O2 → Fe2O3
Which best represents a
balanced equation?
C 2H2 + O2 → 2H20
A solvent has a freezing point of 10°C. What is the most likely freezing point if 5 grams of Salt is mixed with the solvent? (AKS 5e)
Question 5 options:
15°C
20°C
5°C
10°C
[tex]\huge{\color{hotpink}{Hola}}[/tex]
Select the correct answer. Which statement is true for a heating curve?
OA. It shows how the pressure of a substance changes when heated.
ов. It shows how the temperature of a substance changes when heated
OC. It shows how the volume of a substance changes when heated.
OD. It shows how the mass of a substance changes when heated.
please help
Answer:
OB
Explanation:
tht is correct make me brainliest
17 moles of oxygen is equals to how many grams
17 × ( 2 × 16 ) = 17 × 32 = 544 grams
___________________________
Which pair of elements will form an ionic bond?
a. Potassium and Oxygen
b. Iron and Barium
C. Sulfur and Nitrogen
d. Calcium and Silicon
I believe that the answer is A.
The combination of potassium (K) and oxygen (O2) produces K2O (potassium oxide). The balanced equation is 2K + O2 ==> K2O.
An 18.7 g sample of platinum metal increases in temperature from 21.2C to 23.5C
when 5.7 J of heat are added. What is the specific heat of platinum?
Answer:
132.53 J/kg.°C
Explanation:
Applying,
Q = cm(t₂-t₁)................ Equation 1
Where Q = amount of heat, c = specific heat capacity of platinum metal, m = mass of platinum metal, t₁ = initial temperature, t₂ = Final temperature.
Make c the subeject of the equation
c = Q/m(t₂-t₁).............. Equation 2
From the question,
Given: Q = 5.7 J. m = 18.7 g = 0.0187 kg, t₁ = 21.2°C, t₂ = 23.5°C
Substitute these values into equation 2
c = 5.7/[0.0187×(23.5-21.2)]
c = 5.7/0.04301
c = 132.53 J/kg.°C
Answer is B
A metal conducts heat in a similar way to electricity so, as you touch it, it draws heat from your body and makes your hand feel cold.
Plastics don't have to conduct heat so they don't draw heat from your body as efficiently, that's why a piece of plastic feels
than a piece of metal even if it's at the same temperature.
A)
long-chain molecules; warmer
B)
free electrons, warmer
valence electrons; colder
D)
a crystalline lattice; colder
what part of the electromagnetic spectrum was first developed during ww2
Answer:
Radio waves were first developed in WWII
Explanation:
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How many moles of air are there in a 125 mL Erlenmeyer flask if the pressure is 755
mm Hg and the temperature is 20.0°C?
To Find :
How many moles of air are there in a 125 mL Erlenmeyer flask if the pressure is 755 mm Hg and the temperature is 20.0°C .
Solution :
Since, air contains different gas in different proportion.
Its average molar mass is considered to be 29 gram/mol .
Now, we know by ideal gas equation :
[tex]PV = nRT\\\\n = \dfrac{PV}{RT}[/tex]
Here, R is ideal gas equation, [tex]R = 62.363\ mm\ Hg\ L \ mol^{-1} \ K^{-1}[/tex]
Putting all given values we get :
[tex]n = \dfrac{755 \times 0.125}{62.363\times (20+273)}\ moles\\\\n = 0.00516 \ moles[/tex]
Hence, this is the required solution.
Given the equation below, determine the number of moles O2 required to completely react with 28 moles of CO.
Answer:
14 moles of O₂
Explanation:
The reaction between CO and O₂ is the following:
CO + O₂ → CO₂
We balance the equation with a coefficient 2 in CO and CO₂ to obtain the same number of O atoms:
2CO + O₂ → 2CO₂
As we can see from the balanced equation, 1 mol of O₂ is required to react with 2 moles of CO. Thus, the conversion factor is 1 mol of O₂/2 mol CO. We multiply the moles of CO by the conversion factor to calculate the moles of O₂ that are required:
28 mol CO x 1 mol of O₂/2 mol CO = 14 mol O₂
(hurry pls)Carl plugs in a lamp that has 0.67 of resistance and 8.1 volts running through it. What is the amount of current running through the lamp? C 543 A C 0.08 A C 12.09 A C743 A
Answer:
C)12.09 Ampere
Explanation:
V= IR
Where I= current of the system
R= resistance= 0.67 ohm
V= potential difference=8.1 volts
Substitute the values
8.1= I× 0.67
I= 8.1/0.67
=12.09 Ampere
11A) As electrical energy is converted into heat energy, the total amount of energy in the system
pls help me out !
Answer:
b. option Is the correct answer
When a substance changes from a gas to a liquid, what happens to the energy, order, and spacing of
particles within the substance?
I
Answer:
Explanation:
When gas changes to liquid, it releases the thermal energy that has been absorbed before to become gas which does not alter the temperature at all. A reduction in energy changes the arrangement of particle. There spacing between the particles also increases but not as in a gaseous state and so does the kinetic energy. The particles now are now arranged in irregular pattern.
A hydrogen molecule is:
a Polar
b Covalent
C Non-polar
d Both B and C
Explanation:
both b and c since it can be both
A series of logical steps that is followed in order to solve a problem is called the *
1 point
A. experimental process.
B. scientific theory.
D. scientific method
D. model method
Answer:
YUNG PANGATLO LETER D.
Explanation:
YUN ANG SAGUT :>
Answer:
C. Scientific method
Explanation:
we did this in my middle school and this was the only method we were allowed to use to solve problems or questions we had.
What is the oxidation state of Carbon in CaC2O4?
Answer:
The oxidation state of carbon in CaC204 is 3
What were some of the causes of the Amu Darya and Syr Darya rivers being ruined?
urban sewer drainage
tannery dumping
tourism
drying up
agricultural chemicals
Answer:
drying up
agricultural chemicals
Explanation:
WILL GIVE BRAINLIEST!
__ gain electrons in the formation of ionic bonds because they have such high ionization energies indicating a strong attraction between the electrons and the nucleus.
A- metals
B- nonmetals
Answer:
A-Metals
Explanation:
because they have valence electrons
What is the number of moles in 10.62 L of H2S gas at STP?
Answer:
0.474 moles
Explanation:
divide 10.62 by 22.4.