Approximately what percent of the landmass on earth receives
very little or no rainfall?
Answer:
the desert (33% of the worlds surface)
Explanation:
Most of the world's surface is covered in water, in the form of oceans. The remaining landmass of Earth amounts to approximately 29 per cent of the surface. Of this remaining 29 per cent, deserts of all types constitute an estimated 33 per cent, or one-third, of the Earth's total landmass.
What is the percentage of water to land on Earth?
In simplest terms, water makes up about 71% of the Earth's surface, while the other 29% consists of continents and islands.
Which percentage of the total area of the earth is covered by soil?Only about 7.5% of the Earth's surface provides the agricultural soil on which we depend for the world's food supply and this fragment competes, sometimes unsuccessfully, with all other needs: housing, cities, schools, hospitals, shopping centres, landfills, etc.
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Select the correct answer.
What quantity might be measured in units of kilograms?
A.
the brightness of a candle
B.
the volume of a bottle
C.
the mass of a marble
D.
the electric current in a wire
Answer:
The mass of a marble.
Explanation:
Units of the other answers:
A: Light - Lumen (lm)
B: Volume - cm^3
D: Electric current - Ampere
At a pressure of 1 atm, the temperature 115.9 K is called the fill in the blank 1 of Kr . The normal boiling point for Kr is at K The triple point pressure for Kr is atm The critical pressure for Kr is 54.3 atm. At temperatures above 209.4 K and pressures above 54.3 atm, Kr is a _________ . Kr is a _________ at 50.3 atm and 105 K. Kr is a _________ at 0.720 atm and 131 K. Kr is a _________ at 1.00 atm and 118 K.
Answer:
melting point, 119.8 K, 0.72 atm, supercritical fluid, solid, gas, liquid.
Explanation:
Let's refer to the phase diagram (not to scale) for krypton.
At a pressure of 1 atm, the temperature 115.9 K is called the melting point of Kr, and it is the temperature at which it passes from solid to liquid.
The normal boiling point for Kr is at 119.8 K, which is, at 1 atm, the limit between the liquid and the gas state.
The triple point pressure for Kr is 0.72 atm, as can be seen in point C.
The critical pressure for Kr is 54.3 atm.
At temperatures above 209.4 K and pressures above 54.3 atm, Kr is a supercritical fluid, according to the region it is in the phase diagram.
Kr is a solid at 50.3 atm and 105 K, according to the region it is in the phase diagram.
Kr is a gas at 0.720 atm and 131 K, according to the region it is in the phase diagram.
Kr is a liquid at 1.00 atm and 118 K, according to the region it is in the phase diagram.
When elemental sodium reacts with water, sodium hydroxide and hydrogen will form. What mass of sodium (in grams) must be reacted with excess water to produce 325 mL of hydrogen gas at 25.0oC and 1.15 atm?
Answer:
0.703g Na must reacted
Explanation:
The reaction of Sodium, Na, With water, H₂O is:
2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)
Where 2 moles of sodium reacts with an excess of water to produce 1 mole of hydrogen
To solve this question we have to use PV = nTR to solve the moles of the gas. With the moles of hydrogen we can find the moles of sodium that reacted and its mass:
Moles H₂:
PV = nRT
PV /RT = n
Where P is pressure = 1.15atm
V is volume in liters = 0.325L
R is gas constant = 0.082atmL/molK
T is absolute temperature = 25°C + 273 = 298.0K
1.15atm*0.325L / 0.082atmL/molK*298.0K = n
0.0153 moles of hydrogen are produced
Moles Na:
0.0153 moles H₂ * (2moles Na / 1mol H₂) = 0.0306 moles Na
Mass Na -Molar mass: 22.99g/mol-:
0.0306 moles Na * (22.99g / mol) =
0.703g Na must reactedWhat is the empirical formula for a compound if a 2.50g sample contains 0.900g of calcium and 1.60g
of chlorine? (3pts]
Answer:
CaCl₂
Explanation:
First we convert the given masses of elements into moles, using their respective molar masses:
0.900 g Ca ÷ 40 g/mol = 0.0225 mol Ca1.60 g Cl ÷ 35.45 g/mol = 0.045 mol ClNow we divide those numbers of moles by the lowest value among them:
0.0225 mol Ca / 0.0225 mol = 10.045 mol Cl / 0.0225 mol = 2Meaning the empirical formula for the compound is CaCl₂.
I need the correct answers
Answer:
Acids: Tastes Sour
Has a ph less than 7
Base: Bitter
Has a ph greater than 7
slippery
Acid&Base: Conducts electricity
ii) Sodium thiosulphate dissolves in dilute nitric acid at a steady rate. Copy out which
of the following changes would quicken up the reaction- 3
a. Cooling the reacting vessel to drop the temperature.
b. Breaking the reactants into smaller pieces.
c. Adding more concentrated acid.
d. Using more sodium thiosulphate.
Answer:
d
Explanation:
Determine the number of electrons in an Cl ion with a charge of -3
Answer:
There are 20 electrons.
Explanation:
Chlorine has 17 electrons in its atom to begin with (you can tell from the proton number in the periodic table).
A charge of -3 means that the chlorine atom gained 3 electrons, and now needs to lose 3 electrons to return to its atom configuration.
Consider the oxidation of sodium metal to sodium oxide described by the balanced equation:
4 Na + O2 → 2 Na2O. What is the theoretical yield of Na2O in grams from 9.0 mol of O2?
show steps
Answer:
1116 g.
Explanation:
The balanced equation for the reaction is given below:
4Na + O₂ —> 2Na₂O
From the balanced equation above,
1 mole of O₂ reacted to produce 2 moles of Na₂O.
Next, we shall determine the theoretical yield of Na₂O. This can be obtained as follow:
From the balanced equation above,
1 mole of O₂ reacted to produce 2 moles of Na₂O.
Therefore, 9 moles of O₂ will react to produce = 9 × 2 = 18 moles of Na₂O.
Finally, we shall determine the mass in 18 moles of Na₂O. This can be obtained as follow:
Mole of Na₂O = 18 moles
Molar mass of Na₂O = (23×2) + 16
= 46 + 16
= 62 g/mol
Mass of Na₂O =?
Mass = mole × molar mass
Mass of Na₂O = 18 × 62
Mass of Na₂O = 1116 g
Thus, the theoretical yield of Na₂O is 1116 g.
Write a balanced equation for the double-replacement precipitation reaction described, using the smallest possible integer coefficients. A precipitate forms when aqueous solutions of nickel(II) nitrate and sodium carbonate are combined. Do not include states such as (s) or (aq). It is not necessary for you to indicate which of the products is the precipitate.
Answer:
Ni(NO₃)₂ + Na₂CO₃ ⇒ NiCO₃ + 2 NaNO₃
Explanation:
Let's consider the unbalanced equation for the reaction that occurs when aqueous solutions of nickel(II) nitrate and sodium carbonate are combined. This is a double-replacement precipitation reaction.
Ni(NO₃)₂ + Na₂CO₃ ⇒ NiCO₃ + NaNO₃
We will balance the equation using the trial and error method.
First, we will balance Na atoms by multiplying NaNO₃ by 2.
Ni(NO₃)₂ + Na₂CO₃ ⇒ NiCO₃ + 2 NaNO₃
As we can see, the equation is balanced.
3. How many times does earth rotate on its axis in one year?
Answer:
There are approximately 366.25 sidereal days in a year so that the Earth spins 366.25 times with respect to distant stars in a year
hope this helps
have a good day :)
Explanation:
Which of the following is a characteristic shared by all living things?
A. They have tissues and organs,
B. They take in oxygen.
C. They make more individuals of the same kind.
D. They move.
Name the part in red:
H2 + O2 -> H2O
Answer:subscript
Explanation:
The number of atoms in a 158.4 g sample of CO2 gas at STP is:
1.277 x 1025 atoms
2.167 x 1024 atoms
6.502 x 1024 atoms
6.651 x 1024 atoms
Answer:
Option B, 2.167 x 1024 atoms
Explanation:
1 mole of CO2 = 44.01 grams
Number of moles of CO2 in 158.4 gram sample
[tex]\frac{158.4}{44.01} \\3.95[/tex]moles
Number of atoms in one mole is [tex]6.02*10^{23}[/tex]
Number of atoms in 3.95 moles [tex]2.167 *10^{24}[/tex]
Hence, option B is correct
2 Which of the gases in air are elements? Explain how you can tell.
Answer:
I'll explain.
Explanation:
The molecules of two different elements, nitrogen and oxygen, make up about 99 percent of the air. The rest includes small amounts of argon and carbon dioxide. Oxygen is the life-giving element in the air. You can tell because they're on the periodic table which is a table for elements.
Explanation:
nitrogen and oxygen are the gases in the air which are elements you can simply say it by looking the periodic table
In a reaction, the actual yield is always at least as large as the theoretical yield.
True or false.
give short explanation on answer
You tested the rocket with three mixtures of fuel having different masses of oxygen
and hydrogen. What is the relationship between the masses of oxygen and hydrogen in
each of the tests?
Answer:
As the oxygen is only transferred from the copper oxide to form water inside the apparatus, any gain in mass is due to hydrogen combined with the oxygen to form water. The ratio of the two masses enables the mass of oxygen combining with 1 g of hydrogen to be calculated.
Hydrogen and oxygen are the elements used as fuels in rockets as they are propellants. In each of the tests, the ratio of the mass of hydrogen to oxygen is 1:8.
What is the combustion of rocket fuel?Combustion has been the chemical reaction that involves reactants combining and reacting with oxygen resulting in heat and light formation. They are majorly used in propelling engines and in rocket fuels.
In a rocket engine oxygen acts as the oxidizer that reacts with hydrogen atoms to derive the heat and energy so that the engine can move and produce thrust. It uses Newton's third law to create energy and accelerate upwards.
The mixtures of fuel contain various masses that are present in a ratio of 1:8 (hydrogen: oxygen) as masses of hydrogen are 1, 2, and 5 mg, whereas oxygen is 8, 16, and 40 mg. It can be concluded that 1 part of hydrogen reacts with 8 parts of oxygen in the rocket fuel mixture.
Therefore, the rocket fuel mixtures contain a 1:8 ratio of the masses of hydrogen: oxygen that undergoes combustion reaction.
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name the process which takes place when propene gas molecules are converted into a giant molecule
Answer:
Polymerization, any process in which relatively small molecules, called monomers, combine chemically to produce a very large chainlike or network molecule, called a polymer. The monomer molecules may be all alike, or they may represent two, three, or more different compounds.
Please someone answer this asap
Answer:
b or c but I would just pick c
Answer:
C
Explanation:
Sun is an energy source not a matter.
How does nitrogen in the atmosphere become beneficial to plants and eventually animals?
O Nitrogen must be mixed in the soil by earthworms,
O Nitrogen must be converted into a useful form by bacteria,
O Nitrogen must come in contact with decaying organic material,
O Nitrogen must come in contact with the ground through rainfall
Answer:
O Nitrogen must be converted into a useful form by bacteria.
This bacteria is called the nitrogen fixing bacteria such as the Rhizobium bacteria.
of the two Lewis/electron dot
structure representations, which is
the correct one for oxygen gas?
The electron dot diagram for an element shows the valence electrons for the element. Oxygen is in group 16/VIA, so it has six valence electrons. Draw the symbol for oxygen. Then place one dot at each side of the symbol.
Limestone has a density of 2.72 g/cm3. What is the mass of 8.92 cm3 of limestone?
Answer:
[tex]\boxed {\boxed {\sf 24.2624 \ g}}}[/tex]
Explanation:
Density measures mass per volume. The volume is
[tex]\rho=\frac{m}{v}[/tex]
The density of limestone is 2.72 grams per cubic centimeter. We have a piece of limestone with a volume of 8.92 cubic centimeters.
ρ= 2.72 g/cm³v= 8.92 cm₃Substitute the values into the formula.
[tex]2.72 \ g/cm^3=\frac{m}{8.92 \ cm^3}[/tex]
Now we solve for m, the mass, by isolating the variable.
m is being divided by 8.92 cubic centimeters. The inverse of division is multiplication, so we multiply both sides by 8.92 cubic centimeters.
[tex]8.92 \ cm^3 * 2.72 \ g/cm^3=\frac{m}{8.92 \ cm^3}* 8.92 \ cm^2[/tex]
[tex]8.92 \ cm^3 * 2.72 \ g/cm^3=m[/tex]
The units of cubic centimeters cancel out.
[tex]24.2624 \ g =m[/tex]
The mass of this piece of limestone is 24.2624 grams.
Which statement best explains the genetic variation that results from sexual
reproduction?
A. Each chromosome contains many different genes.
B. Offspring receive a mix of genes from two different parents.
c. Offspring receive genes that are exactly the same as one parent's
genes.
O D. Each chromosome contains many copies of the same gene.
Answer:
Each chromosome contains many copies of the same gene
Answer:
Offspring receive a mix of genes from two different parents
Good luck!
What is the energy of a photon?
A. A photon has no energy.
B. The energy of a photon is hxc.
c. The energy of a photon is hx 2.
D. The energy of a photon is h* f.
Write out and balance the chemical equation:
A solution of nickel (II) chloride reacts with a solution of potassium hydroxide
to produce solid nickel (II) hydroxide and a solution of potassium chloride.
Explanation:
NiCl2 + KOH = NiOH + KCl
since nickel is the primary element in nickel ii chloride, find the oxidation no of nickel in the compound and chlorine should have 2 as a subscription since the ii in the compound represents that nickel has an oxidation no of 2
Which of the two Lewis/electron dot structure representations, which is
the correct one for oxygen gas? PICTURE BELOW
Answer:
A
Explanation:
_____ is the process of linking smaller molecules to form long chains of higher molecular weight.
what is the chemical equation for aq nitrate ion reacts with s arsenic trihydride and produces s arsenic and g ammonia?
Answer:
Explanation:
131.39 g/mol C2HCl3
find the molecular formulas
Answer:
Find the mass of 1 mole.
mass of
1
mole of
131.39
g
m
o
l
C
2
H
C
I
⋅
3
=
37.04000067
g
Explanation:
hope it helps make brainlliest ty
A___
is a
small, rocky object
that orbits the sun
and has broken
off from a comet
or asteroid.
(Fill in the blank)
Answer:
I think it is a rock...
Explanation:
maybe idrk tho