If 15.0 g of nitrogen reacts with 15.0 g of hydrogen, 10.5 g of ammonia is
produced. What is the percent yield?

Answer:

719.83°C

Explanation:

The heat that the sample of Zinc gives is equal to the heat that water is absorbing. That is:

C(Zn) * m(Zn) * ΔT(Zn) = C(H2O) * m(H2O) * ΔT(H2O)

Where:

C is specific heat (Zn: 0.390J/g°C; H2O: 4.184J/g°C)

m is mass (Zn: 2.50g; H2O: 65.0g)

ΔT (Zn: ?; H2O: (22.5°C - 20.0°C = 2.50°C)

Replacing:

0.390J/g°C * 2.50g * ΔT(Zn) = 4.184J/g°C * 65.0g * 2.50

ΔT(Zn) = 697.33°C

As final temperature of Zn is 22.50°C, initial temperature is:

Initial temperature: 697.33°C + 22.50°C

719.83°C

1. C

2. D (I’m not entirely sure)

3.energy can neither be created nor destroyed, only change forms.

4. C

5. A

6. C

I’ve researched and tried to answer these questions correctly.

Answer:

1.c

2.a

3.created or destroyed

4.c

5.a

6.c

Explanation:

thanks me later

Answer:

A pure substance has a definite chemical composition

A pure substance has a definite chemical composition in all states. Pure substance can be composed of multiple elements but the composition does not alter in any case.

Pure substances are formed either a single component or a combination of more components with a definite composition forming a single phase. Unlike mixtures a pure substance cannot be separated into its components physically.

For example pure water is a pure substance. Water is formed from hydrogen and oxygen atoms in a definite proportion forming a molecular compound that does not alter anyway.

However, salt solution, mixture of two gases etc. are not pure substance. They haven't a definite composition and can be separated by some physical methods. Hence, option c is correct.

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Answer:

B. The nickle Metal

Explanation:

A P E X

Answer:

3,717,813

Im not sure, I will get back to you soon

Answer:

?

Explanation:

Answer:

electric field or magnetic field both are same

Explanation:

in an electromagnet the movement of electrons in a wire creates the magnetic field.an electromagnet and the permanent magnet both the magnet have the magnetic fields that can attract the same kinds of materials.

Answer:

rust

Explanation:

To Find :

How many molecules are in 23 moles of oxygen (O₂).

Solution :

We know, 1 mole of any atom/molecule contains 6.022 × 10²³ numbers of atoms/molecules.

So, number of molecules in 23 moles of O₂ are :

[tex]n= 23\times 6.022\times 10^{23}\\\\n =138.506\times 10^{23}\\\\n = 1.385 \times 10^{25}\ molecules[/tex]

Hence, this is the required solution.

Answer:

B

Explanation:

b/c air is not seen by eye

Answer:

9vguvvg9uvu

Explanation:

The mass of one mole or 6.02 × 10²³ molecules of water is 18 g/mol. Then, the mass of one molecule of water is 2.99 × 10⁻²³ g/molecule.

The number of atoms that constitutes one mole of a substance is called Avogadro number. It is equal to  6.02 × 10²³. Thus, one mole of every elements contains Avogadro number of atoms.

Similarly, one mole of a compound contains  6.02 × 10²³ number of molecules. Thus, one mole of water contains these much molecules. The mass of one mole of an element is called its atomic mass. Similarly the mass of one mole of a compound is called its molar mass.

Molar mass of water = 18 g/mol

18 g is the mass of 6.02 × 10²³  molecules of water. Hence, the mass of one molecule of water is;

= 18 g/mol/6.02 × 10²³ molecule/mol

= 2.99 × 10⁻²³ g/molecule

Therefore, the mass of one molecule of  H₂O  is 2.99 × 10⁻²³ g/molecule.

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Answer:

3. x 10⁸m/s

Explanation:

Given parameters:

Frequency of wave  = 7.8 x 10⁶Hz

Unknown:

Speed of the wave = ?

Solution:

All electromagnetic radiation has  a speed of 3. x 10⁸m/s in free space.

No matter the frequency and wavelength, they all have the same speed which is the same as the speed of light.

The speed of electromagnetic wave that has a frequency of [tex]7.8 * 10^{6}[/tex] Hz is [tex]3 * 10^{8}[/tex] m/s.

Electromagnetic waves:

Higher-frequency electromagnetic waves have less energy. All electromagnetic waves travel across space at the speed of light which is  [tex]3 * 10^{8}[/tex] m/s.

As we know that,

Speed=frequency x wavelength,

It follows that the wavelength will also not change. So the direction, speed, frequency and wavelength of any electromagnetic wave are constant and these properties will not change after emission from a source.

Thus, speed of an electromagnetic wave is fixed and does not change on varying frequencies which is [tex]3 * 10^{8}[/tex] m/s.

OR

The waves travel at the same speed, but the observed frequency depends on any relative motion between the observer and source.

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Answer:

B or C

Explanation:

I don't really know sorry.

Answer:

D

Explanation:

I think D I also took the test.

Answer:

protons = 9

neutrons = 10

electrons = 9 because it is neutral atom

Explanation:

atomic number= protons = 9

atomic mass= protons + neutrons

19= 9 + n

n= 10

Answer:

the rate is faster, and the time of reaction is 28 seconds

Explanation:

i did the test

Answer:

The rate is faster, 28 seconds

Explanation:

Answer: Answer to your question is B. I did a science

Explanation: Test was to see which would dissolve fastest...

Answer:

Ca + AgNO3 ---> Ca(NO3)2 + Ag

Calcium + silver nitrate ---> Calcium nitrate + silver

also ...reaction type is Single displacement reaction .

hope this answer's your question.

Answer:

A unit of mass used to express atomic and molecular weights, equal to one-twelfth of the mass of an atom of carbon-12. It is equal to approximately 1.66 x 10-27 kg.

Explanation:

Answer:

a unit of mass used to express atomic and molecular weights, equal to one-twelfth of the mass of an atom of carbon-12. It is equal to approximately 1.66 x 10-27 kg.

Explanation:

hope it helps, mark brainliest please

Answer:

Scale is the right answer

Explanation:

The  scale is a sentence that relates distance on the map to distance on Earth

The scale of a map represents the relationship between the distances on the map and the actual distances on Earth.

A map is a symbolic representation of selected features of a location, typically drawn on a flat surface. Maps present information about the world in a straightforward, visual format. They teach about the world by displaying country sizes and shapes, feature locations, and distances between locations.

The ratio of a distance on Earth to the same distance on a map is known as map scale. On maps, three types of scales are commonly used: written or verbal scales, graphic scales, and fractional scales.

The map scale is the relationship between the distance on a map and the actual distance on Earth.

Thus, The scale of a map represents the relationship between the distances on the map and the actual distances on Earth.

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Answer:

If it took the motorcycle 2 hours to cover 20km, then the average speed is 10km per hour.

Explanation:

Speed is equal to distance over time. So 20km divided by 2 hours is 10 km per hour.

Please mark brainliest!!! Thanks.

Answer:

96.56063 km/h

Explanation:

Aluminum has the larger atomic radius.

silicone is larger than carbon.

Aluminum is larger than silicon

I think silicon is the answer

Answer:

A permanent magnet has two different magnetic poles, called the north and south poles. The field lines are inside the magnet. Magnetic poles of the same charge repel each other. Thus, the north pole with another north, the south pole and with another south pole are repelled.

Explanation:

Answer:

Synthesis

The first reported synthesis of selenium tetrafluoride was by Paul Lebeau in 1907, who treated selenium with fluorine:[1]

Se + 2 F2 → SeF4

A synthesis involving more easily handled reagents entails the fluorination of selenium dioxide with sulfur tetrafluoride:[2]

SF4 + SeO2 → SeF4 + SO2

An intermediate in this reaction is seleninyl fluoride (SeOF2).

Other methods of preparation include fluorinating elemental selenium with chlorine trifluoride:

3 Se + 4 ClF3 → 3 SeF4 + 2 Cl2

Structure and bonding

Selenium in SeF4 has an oxidation state of +4. Its shape in the gaseous phase is similar to that of SF4, having a see-saw shape. VSEPR theory predicts a pseudo-trigonal pyramidal disposition of the five electron pairs around the selenium atom. The axial Se-F bonds are 177 pm with an F-Se-F bond angle of 169.2°. The two other fluorine atoms are attached by shorter bonds (168 pm), with an F-Se-F bond angle of 100.6°. In solution at low concentrations this monomeric structure predominates, but at higher concentrations evidence suggests weak association between SeF4 molecules leading to a distorted octahedral coordination around the selenium atom. In the solid the selenium center also has a distorted octahedral environment.

Reactions

In HF, SeF4 behaves as a weak base, weaker than sulfur tetrafluoride, SF4 (Kb= 2 X 10−2):

SeF4 + HF → SeF3+ + HF2−; (Kb = 4 X 10−4)

Ionic adducts containing the SeF3+ cation are formed with SbF5, AsF5, NbF5, TaF5, and BF3.[3] With caesium fluoride, CsF, the SeF5− anion is formed, which has a square pyramidal structure similar to the isoelectronic chlorine pentafluoride, ClF5 and bromine pentafluoride, BrF5.[4] With 1,1,3,3,5,5-hexamethylpiperidinium fluoride or 1,2-dimethylpropyltrimethylammonium fluoride, the SeF62− anion is formed. This has a distorted octahedral shape which contrasts to the regular octahedral shape of the analogous SeCl62−. [5]

Explanation:

One of the most polluting being city sewage and industrial waste discharge. Indirect sources of water pollution include contaminants that enter the water supply from soils or groundwater systems and from the atmosphere via rain.

Answer:

gas gets dumped is one and the other is dumping trash into water

Explanation:

Answer:

6. Color Change.

Production of an odor.

Change of Temperature.

Explanation:

That is the only one I know :)

Answer:

6. 3 things could potentially be, a change in mass, a change in color, or a change in weight. obviously there are more, but these are 3.

I'm sorry I couldn't answer more of these question of yours, I don;t know too much about aluminium :/

May I have brainliest please? :)

Answer:

Divide 837.4 g by 18.015 g/mol to get moles of H2O

Multiply moles of H2O by 6.022 x 10^23 molecules/mol to get molecules (of H2O in 837.4 g)

Round off your final answer to 4 sig figs.

Thank you and please rate me as brainliest as it will help me to level up

Answer:

0.75M Fe²⁺

Explanation:

First, we need to balance the redox reaction in acidic medium. Then, we can obtain moles of KMnO4 and with the reaction moles and molarity of the Fe²⁺ solution:

Redox Balance:

Fe²⁺ → Fe³⁺ + 1e⁻

5e⁻ + 8H⁺ + MnO₄⁻ → Mn²⁺ + 4H₂O

___________________________

5Fe²⁺ + 5e⁻ + 8H⁺ + MnO₄⁻ → 5Fe³⁺ + 5e⁻ + Mn²⁺ + 4H₂O

Moles of KMnO₄:

70.0mL = 0.0700L * (0.150mol / L) = 0.0105 moles KMnO₄

Moles and molarity Fe²⁺:

0.0105 moles KMnO₄ * (5 moles Fe²⁺ / 1mol KMnO₄) = 0.0525 moles Fe²⁺

In 70.0mL = 0.0700L:

0.0525 moles Fe²⁺ / 0.0700L =

Answer:

 r =  [tex]\sqrt{\frac{v}{\pi h} }[/tex]

27.2cm

Explanation:

Given parameters:

Height of tank  = 6461.76cm

Volume of water  = 15000000cm³

Volume of cylinder  = [tex]\pi[/tex] r² h

i. Express radius in terms of volume;

  we are to make radius the subject of the expression;

              v = [tex]\pi[/tex] r² h  

     divide both sides by πh

         [tex]\frac{v}{\pi h}[/tex]   = [tex]\frac{\pi r^{2}h }{\pi h }[/tex]  

              r²   =  [tex]\frac{v}{\pi h}[/tex]

              r =  [tex]\sqrt{\frac{v}{\pi h} }[/tex]

ii.

Radius of the water tank;

             r  = [tex]\sqrt{\frac{15000000}{\pi x 6461.76} }[/tex]   = 27.2cm