What causes fireworks

Answer:

2.5 I don't have a explanation

Answer:

A. The color change from blue to green happens in nature.

Explanation:

The color change is an indicator of a chemical reaction that has occurred. Although color changes are not necessarily good diagnostic tool to measure if a chemical reaction has occurred or not.

The evidence that shows that a chemical reaction has taken place is the disappearance of the steel wool shows that a new substance has formed.

The electrochemical series is arrangement of elements in order of decreasing reactivity. It is important to note that the elements that are high up in the electrochemical series can displace the elements that are lower in the series from their aqueous solution.

Steel contains iron which lies above copper in the electrochemical series hence a chemical change occurs when steel dissolves in the copper solution.

Hence, the evidence that shows that a chemical reaction has taken place is the disappearance of the steel wool shows that a new substance has formed.

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Answer:

E = 3.035× 10-¹⁹J = 1.9eV

f = 4.58 × 10¹⁴Hz

Explanation:

wavelength = 6.55 × 10-⁷m

c = 3 × 10⁸m/s

f = ?

E = ?

a) f = c/wavelength

f = 3 × 10⁸/6.55 × 10-⁷

f = 4.58 × 10¹⁴Hz

b) E = hc/wavelength

E = 6.626×10-³⁴ × 3 × 10⁸/ 6.55 × 10-⁷

E = 3.035 × 10-¹⁹J

1ev = 1.6 × 10-¹⁹J

Therefore E = 3.035/1.6 = 1.9eV

Answer:

A Transverse Wave

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.

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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Answer:

Explanation:

Both plastic and gasoline are products of pretroleum

Answer:  Check my answers.

Explanation:

There are four classes of macromolecules (polysaccharides or carbohydrates, triglycerides or lipids, polypeptides or proteins, and nucleic acids such as DNA & RNA). Carbohydrates and lipids are made of only carbon, hydrogen, and oxygen (CHO). Proteins are made of carbon, hydrogen, oxygen, and nitrogen (CHON).

Answer:

Grating

Explanation:

I think you need to grate it

Answer: The sugar would dissolve in water. You could then pour off the solution and wash the remaining sand with a bit more water. Heat the water to evaporate it from the sugar, and the two are separate

Explanation:

Answer:

A wave with a higher frequency have a shorter wavelength, the higher the sound it, the closer the arcs of the wavelength are, the faster the sound is, the shorter they are.

According to scied.ucar.edu  ~  "The frequency of a wave is inversely proportional to its wavelength. That means that waves with a high frequency have a short wavelength, while waves with a low frequency have a longer wavelength. Light waves have very, very short wavelengths."

Hope this helps

Explanation:

May I have brainliest please? :)

A wave with a higher frequency has a longer wavelength is a false.

A wave with a higher frequency has a longer wavelength is a false statement because shorter wavelength have higher frequency and also higher energy.

We know that longer wavelength of a wave having shorter frequency and shorter energy while on the other hand, the shorter wavelength of a wave having higher frequency and higher energy so we can conclude that the statement is false.

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Answer:

I think the answer is A. I am only 50% sure I am correct, but hope it helps!

Explanation:

Answer:

V = 16.81 L

Explanation:

Given data:

Number of moles = 0.75 mol

Temperature = standard = 273 K

Pressure = 1 atm

Volume of balloon = ?

Solution:

The given problem will be solve by using general gas equation,

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

Now we will rearrange the formula.

V = nRT/P

V = 0.75 mol ×0.0821 atm.L/mol.K ×273 K / 1 atm

V = 16.81 atm.L/ 1 atm

V = 16.81 L

a. The symbol [tex]\tt _{11}^{23}Na[/tex], [tex]\tt _{18}^{40}Ar[/tex], [tex]\tt _{15}^{31}P^{3-}[/tex], [tex]\tt _{13}^{27}Al^{3+}[/tex]

b. Isotope of Na

Atomic number=number of protons=number of electrons(neutral atom)

Number of neutrons=mass number-atomic number

Mass number=protons+neutrons

B. atomic number=11, mass number=11+12=23⇒Sodium

[tex]\tt _{11}^{23}Na[/tex]

C. atomic number=18, mass number=18+22=40⇒Argon

[tex]\tt _{18}^{40}Ar[/tex]

D. atomic number=15, mass number=15+16=31, charge -3(electron-proton)⇒Phosphor

[tex]\tt _{15}^{31}P^{3-}[/tex]

E. atomic number=13, mass number=13+14=27, charge +3(proton-electron)⇒Aluminium

[tex]\tt _{13}^{27}Al^{3+}[/tex]

Isotope=the same atomic mass, different neutron(mass number)

So the atom⇒isotope of Sodium(Na)

Answer:

B: nuclear energy.

Explanation:

It is emission-free and it saves 2.4 billion tons of carbon emissions per year. Also, the level of hazard of nuclear waste does decrease during the time.

Hope that helps!

Answer: i think it is A

Explanation:

hope this helps!

Answer:

3 sig figs

Explanation:

Answer+Explanation:

Titanium ( in place of iron)

Titanium could be an excellent replacement for iron when it comes to tensile strength versus weight. It would be the first choice as a building material metal and building skeletons/bridges would use titanium instead of iron.

Magnesium alloys (in place of aluminum)

Magnesium alloys potentially met the present demands for lighter and reliable construction. With comparable specific stiffness, higher specific strength and energy absorption magnesium alloys have the potential to replace steel and aluminum alloys.

aluminum (in place of copper)

Most non-copper metal cabling is aluminum, and it is often used in areas where copper is not a likely alternative. However, it is used more now as a replacement than it has ever been. It is cheaper than copper, and its relative density allows for more cable to be made from a ton of aluminum than a ton of copper.

hope it helps you

Answer:

what

Explanation:

I cant see your question yet

Answer:

the question really said :

Answer:

Deposition

Explanation:

Deposition is the phase transition in which gas transforms into solid without passing through the liquid phase. Deposition is a thermodynamic process. The reverse of deposition is sublimation and hence sometimes deposition is called desublimation.

Answer:

Helium

Radon

and Neon

Explanation:

Answer:

1-

A) H2O        B) HCO3-

2-

A) NH3         B) SO3-2

Explanation:

Answer:

[tex]\huge\boxed{\sf Acid}[/tex]

Explanation:

An acid has the following properties:

=> Is corrosive to Iron and reacts with it.

=> Has a sour taste.

=> Produces a burning sensation when touched.

So, Substance A is an acid.

[tex]\rule[225]{225}{2}[/tex]

Hope this helped!

Answer:

Explanation:

Groundwater spread over the years

Answer:

what that girl said lol

Answer:

honestly.. idk lol

Explanation:

Answer:

a. CH3

Hope this helps.

Answer:

Open ended question

Explanation:

Built different :]

Answer:

if an OPEN end question is too challenging respondents will abandon the surevy

Explanation:

The source of alpha particles in a smoke detector is the Americium.

Answer:

A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms.

Explanation:

Answer:

3Mg + 2AlCl3 --> 2Al + MgCl2