a student practicing for a track meet ran 300 meters in 30 seconds. what was her average speed?​

Answer:

Mass = 1188.13 g

Explanation:

Given data:

Mass of ZnO produced = ?

Moles of oxygen = 7.3 mol

Solution:

Chemical equation:

2Zn + O₂       →      2ZnO

Now we will compare the moles oxygen and and ZnO.

               O₂          ;        ZnO

                1            :           2

              7.3          :           2/1×7.3 = 14.6 mol

Mass of ZnO:

Mass = number of moles × molar mass

Mass = 14.6 mol × 81.38 g/mol

Mass = 1188.13 g

Answer:

C. The gas enters the cryosphere as ice sheets

Answer:

D

Explanation:

The atomic mass of Copper : 63.6166 amu

Given

Copper-63 is 69.17%

Copper-65 is 30.83%

Required

The atomic mass of Copper

Solution

The elements in nature have several types of isotopes

Atomic mass is the average atomic mass of all its isotopes

Mass atom X = mass isotope 1 . % + mass isotope 2.%  ...

The atomic mass of Copper = 0.6917 x 63 + 0.3083 x 65

The atomic mass of Copper = 43.5771 + 20.0395

The atomic mass of Copper = 63.6166 amu

Answer:

The answer is 20mph

Hope this helps!!!

This question was posted more than a month ago so... I guess I'll take the points if you don't mind?

Answer:

I think its might be 1 because the ionic numbers for CA is +2 and for P its +3

Answer:

The answer is 5,434.8 cm^3

The volume corresponding to 5,000 g of ice with a density of 0.92 g/mL is 5.4 × 10³ mL.

The density (ρ) is an intrinsic property of matter. It is equal to the quotient between the mass (m) and the volume (V). If we have 5,000 g of ice with a density of 0.92 g/mL, its volume is:

[tex]\rho = m/V\\V = m/\rho = 5,000 g/(0.92 g/mL) = 5.4 \times 10^{3} mL[/tex]

The volume corresponding to 5,000 g of ice with a density of 0.92 g/mL is 5.4 × 10³ mL.

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Answer:

B. an atom of oxygen o is destroyed in the reaction

Answer:

The heat energy released during nuclear fusion

The heat energy released during nuclear fusion. The correct option is D.

Thus, The Sun and other stars are powered by nuclear fusion reactions. A heavier nucleus is created when two light nuclei fuse together in a fusion reaction.

Because the mass of the resulting single nucleus is smaller than the combined mass of the two initial nuclei, the process produces energy. Remaining mass is converted to energy.

Why this happens is explained by Einstein's equation (E=mc2), which states in part that mass and energy can be transformed into one another. Fusion energy could be a significant source of energy generation if scientists can figure out how to use it in equipment on Earth.

Thus, The heat energy released during nuclear fusion. The correct option is D.

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a. 661.23 m/s

b.  the rate of effusion of Ammonia = 4.5 faster than Silicon tetra bromide

Given

T = 25 + 273 = 298 K

Required

a. the gas speed

b. The rate of effusion comparison

Solution

a.

Average velocities of gases can be expressed as root-mean-square averages. (V rms)  

[tex]\large {\boxed {\bold {v_ {rms} = \sqrt {\dfrac {3RT} {Mm}}}}[/tex]

R = gas constant, T = temperature, Mm = molar mass of the gas particles  

From the question  

R = 8,314 J / mol K  

T = temperature  

Mm = molar mass, kg / mol  

Molar mass of Ammonia = 17 g/mol = 0.017 kg/mol

[tex]\tt v=\sqrt{\dfrac{3\times 8.314\times 298}{0.017} }=661.23~m/s[/tex]

b. the effusion rates of two gases = the square root of the inverse of their molar masses:  

[tex]\rm \dfrac{r_1}{r_2}=\sqrt{\dfrac{M_2}{M_1} }[/tex]

M₁ = molar mass Ammonia NH₃= 17

M₂ =  molar mass Silicon tetra bromide SiBr₄= 348

[tex]\rm \dfrac{r_1}{r_2}=\sqrt{\dfrac{348}{17} }=4.5[/tex]

the rate of effusion of Ammonia = 4.5 faster than Silicon tetra bromide

Answer:

The mass remains constant

Explanation:

Burning a wood is a chemical change which produces many products. According to the law of conservation of mass, matter is neither created nor destroyed in a chemical reaction.

Answer:

Covalent bonds form when electrons are shared between atoms and are attracted by the nuclei of both atoms.

Answer:

C) The products have more energy stored in their chemical bonds.

Explanation:

In such reactions that absorb energy, the products have more energy stored in their chemical bonds.

For endothermic changes, heat is absorbed from the surrounding hence the surrounding becomes colder at the end of the changes.

The heat energy level of the products is higher than that of the reactants.

Answer: The reactivity of group 7 decreases as we move down the group because:

Explanation:

The elements of group 7 that is fluorine to iodine. The halogens are non metals and they react with metals to gain electrons. The metals loose electrons and the non metal gains it.

As we move down the group  the atomic radius gets bigger( more electron and more proton) and as a result the outer shells move further away from the nucleus.

There is more distance between the negatively charged electrons and positively charged nucleus.

Therefore the force of attraction between the shells and nucleus is lesser or weaker.

This makes attracting an extra electron from metals very difficult which results in weaker reaction.

Consequently, the reactivity decreases as we move down the group 7

Answer:

T^2 α r^3

Explanation:

The relationship between the period of revolution of planets and their mean distances from the sun is given by Kepler's third law.

Kepler's laws of planetary motion describe the orbits of objects around the sun.

This third law states that; "the square of the period of revolution of planets are proportional to the cubes of their mean distances from the sun. Hence; T^2 α r^3.

Where;

T = period of revolution of the planets

r = mean distance of the planet from the sun

Answer:

Scientists must collect accurate information that allows them to make evolutionary connections among organisms. Similar to detective work, scientists must use evidence to uncover the facts. In the case of phylogeny, evolutionary investigations focus on two types of evidence: morphologic (form and function) and genetic.

Explanation:

This what I think

Answer:

C

Explanation:

Just like a Alligator or Croc, they evolved from the dinosuar's. The scientest KNOW THIs mainly because they have compared the fossil's of a crocidile THEN and a corcidile NOW (Just a example)

Hope this helps and pls mark brainlest!

Answer:

Ionic bonds form when a nonmetal and a metal exchange electrons, while covalent bonds form when electrons are shared between two nonmetals.

Answer:

It's considered a limited resource because there is a limited amount of freshwater found on Earth's surface. Explain why the amount of water per person differs between countries. It differs because in the different countries it is distributed unevenly.

Explanation:

looked it up

Answer: The time after which the concentration of [tex]SO_2Cl_2[/tex] fall to 12.5% of its initial value is 26.2 hours

Explanation:

Expression for rate law for first order kinetics is given by:

[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]

where,

k = rate constant  

t = age of sample

a = let initial amount of the reactant  = 100

a - x = amount left after decay process  = 12.5

a) for completion of half life:  

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

[tex]t_{\frac{1}{2}}=\frac{0.693}{k}[/tex]

[tex]k=\frac{0.693}{8.75hour}=0.0792hour^{-1}[/tex]

b) for concentration to fall to 12.5 % of initial value  

[tex]t=\frac{2.303}{0.0792}\log\frac{100}{12.5}[/tex]

[tex]t=26.2hours[/tex]

The time after which the concentration of [tex]SO_2Cl_2[/tex] fall to 12.5% of its initial value is 26.2 hours

Answer:

C. 1.5 m copper(II) sulfate(aq)

Explanation:

I say this because a copper is a metal and a metal always has the highest melting and boiling point. A metal is also malleable, can dissolve in water, and a good conductor of electricity. All the other answers have all the nonmetals in them like Carbon, Oxygen, Chlorine, and etc. Nonmetals do not have a high boiling point. They basically are brittle. Therefore, the final answer is C.

Answer:

the answer is the second one.

Answer:

6.25%

Explanation:

Given data:

Half life of lutetium-117 = 6.75 days

Percentage remaining after 27 days = ?

Solution;

Number of half lives = Time elapsed / half life

Number of half lives = 27 days / 6.75 days

Number of half lives = 4

At time zero = 100%

At first half life = 100%/2 = 50%

At second half life = 50%/2 = 25%

At 3rd half life = 25%/2 = 12.5%

At 4th half life = 12.5%/2 = 6.25%

Answer:

elllo

Explanation:

Answer:

I think scientists should not clone the wooly mammoth because our environment is already working great without them and bringing them back has a chance to hurt the environment or even destroy it also wooly mammoths were exists about 3700 years ago and the world had changed A LOT from then so we could end up hurting the mammoth by putting it in a world that has changed a lot from when the wooly mammoth was actually alive.

Answer:

Contemporary light microscopes are able to magnify objects up to about a thousand times. Since most cells are between 1 and 100 μm in diameter, they can be observed by light microscopy, as can some of the larger subcellular organelles, such as nuclei, chloroplasts, and mitochondria.

Answer:

4.59 grams of hydrogen

Explanation:

57.010 g of ammonium phosphate * 1 mol / 149 g of ammonium phosphate * 12.0 g H * / 1 mol = 4.591409396.

But with sig figs, it rounds to 4.59.

So the final answer is 4.59 grams of hydrogen.

4.59g is the  mass of hydrogen in 57.010 grams of ammonium hydrogen phosphate. A mole is just a measuring scale.

A mole is just a measuring scale. In reality, it is one of the International System for Units' seven foundation units (SI). When already-existing units are insufficient, new ones are created. Using absolute amounts of atoms, molecules, or ions would be problematic as well since chemical reactions frequently occur at levels that use grams would be inappropriate.

A mole consists of precisely 6.022140761023 particles. The "particles" might be anything, from tiny things like electrons and atoms to enormous things like stars or elephants.

57.010 g of ammonium hydrogen phosphate× 1 mol / 149 g of ammonium phosphate ×12.0 g H× / 1 mol = 4.59g of hydrogen

Therefore, 4.59g is the  mass of hydrogen in 57.010 grams of ammonium hydrogen phosphate.

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Answer:

MOON

Explanation:

ITS PERIOD OF REVOLUTION IS EQUAL TO PERIOD OF ROTATION

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Answer:

the particles expand and the kinetic energy i think moves slower

Explanation:

Answer:

Absolute zero is the temperature at which the particles of matter (molecules and atoms) are at their lowest energy points. Some people think that at absolute zero particles lose all energy and stop moving. This is not correct. ... Scientists use lasers to slow atoms when cooling objects to very low temperatures.

Answer:

13.749 x 10 -3 g

Explanation:

take the number of atoms that you have divided by Avogadro's number and then multiply by the molar mass of the element. :)