9. Use dot and cross diagrams to represent the following compounds.
a. Sodium chloride (NaCl)​

Answer: 5.248

Explanation: 0.53/0.1010 = 5.24752475248, and round to the thousandths.

Answer:

the answer is burning a match

Explanation:

when you break glass, the  properties of glass is still the same, melting ice and boiling water are both phyisical changes since they are chnages in state.

woo burning is a type of combustion reaction and when we light a match, matches include different chemicals that help to ignite it with friction so its A, burning a match

Answer:

A. burning a match on edge 2021

Answer:

The two substances are Grease and Oil.

Explanation:

- Grease is used for other lubrication outside of the engine when it is really cold.

- Oil is used for lubricating when your engine is really hot.

Answer:

73 days

Explanation:

From the question given above, the following data were obtained:

Half life (t½) = 18.2 day.

Original amount (N₀) = 0.70 g

Amount remaining (N) = 0.04375 g

Time (t) =.?

Next, we shall determine the rate of decay of the isotope. This can be obtained as follow:

Half life (t½) = 18.2 day.

Decay constant (K) =.?

K = 0.693 / t½

K = 0.693 / 18.2

K = 0.038 /day

Finally, we shall determine the time taken for the isotope to decay to 0.04375 g. This can be obtained as follow:

Original amount (N₀) = 0.70 g

Amount remaining (N) = 0.04375 g

Decay constant (K) = 0.038 /day

Time (t) =.?

Log(N₀/N) = kt /2.303

Log (0.70/0.04375) = (0.038 × t) /2.303

Log 16 = (0.038 × t) /2.303

1.2041 = (0.038 × t) /2.303

Cross multiply

1.2041 × 2.303 = 0.038 × t

Divide both side 0.038

t = (1.2041 × 2.303) / 0.038

t = 72.97 ≈ 73 days

Therefore, it will take approximately 73 days for the isotope to decay to 0.04375 g

When paper is burned, the mass of the remaining ash is less than the mass of the original paper because Some of the products of the reaction were given off as a gas.

The postulate of the law of conservation of mass is that mass can not be created or destroyed rather it can be transformed from one form to another.

This means that when ash is left behind after burning paper, the total mass should be the same as was obtained before combustion but it rather weighs less than paper itself. This should never be interpreted to mean that mass was "lost".

Here is what happens, paper is an organic material and burning it in air yields CO2 gas which escapes into the atmosphere. This explains why; when paper is burned, the mass of the remaining ash is less than the mass of the original paper.

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Answer:

it doesnt even give you enough information for you to answer it

Explanation:

Answer:

it doesnt even give you enough information for you to answer it

Explanation:

Answer:

D

Explanation:

Move the decimal and count the places

Answer:

0.497 moles/L

Explanation:

The reaction that takes place is:

First we calculate the moles of lactic acid in 0,821 g, using its molar mass:

One mole of lactic acid reacts with one mole of sodium hydroxide (it is a monoprotic acid), so in 18,34 mL of NaOH solution there are  9,122x10⁻³moles of NaOH:

The greenhouse effect is a process in which gases in the atmosphere keep heat near earth and prevent it from radiating into space.

Greenhouse effect can be described as the process by which radiations from the sun are absorbed by greenhouse gases and do not travel back into space. This prevents the surface of the earth from freezing.

The sun heats up the earth’s atmosphere during the day and the earth cools down at night by radiating heat back into the atmosphere. The heat is absorbed by the greenhouse gases and makes the surface of the earth warmer, which makes the survival of living beings on earth possible.

But because of the increased levels of greenhouse gases, the temperature of the earth has considerably increased. The major contributors to greenhouse gases are automobiles, deforestation,  factories, etc. which increases the amount of these gases in the atmosphere.

The greenhouse gases do not allow radiation or heat to escape from the earth and increasing the surface temperature of the earth and leading to global warming.

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Answer:

288 grams

Explanation:

The amount of any radiative substance left after some time is calculated by

amount left = [tex]x/2^n[/tex]

where x is the initial amount of substance

n is the number of half lives

one half live is the time in which amount of substance reduce to half of its initial value.

------------------------------------------------------

amount left = 4.5 grams

half life of  iodine-125 = 60 days

total time in which substance reduced to 4.5 grams  = 360 days

thus,

number of half life in 60 days = 360/60 = 6

thus, there are period of 6 half lives

in each half life the amount of substance reduces to its previous half

let the initial amount be x grams

using the formula

amount left = [tex]x/2^n[/tex]

[tex]4.5 = x/2^6 \\ 4.5 = x/64\\x = 4.5*64 = 288[/tex]

Thus, 288 grams was the initial amount of iodine-125

Answer:

7.11 x [tex]10^{14}[/tex] Hz

Explanation:

The equation for converting wavelength to frequency is ν=c/λ, or the speed of light over wavelength. The speed of light is 3.00 x [tex]10^{8}[/tex], and our wavelength here is 422 x [tex]10^{-9}[/tex]. All we have to do now is substitute our given values:

[tex]\frac{3.00x10^{8} }{422x10^{-9}}[/tex]

After reduction, our answer comes out to be about 7.11 x [tex]10^{14}[/tex] Hz.

Answer to Question.

A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.

Answer:

B. They move freely in all directions.

Explanation:

i got it right on my test on edge

Answer:

B. They move freely in all directions.

Explanation:

Answer:

D. Luster

Explanation:

Luster describes how a mineral reflects off light. It is in the definition.

Answer:

Copy and paste "Electromagnetic waves are categorized according to their frequency f or, equivalently, according to their wavelength λ = c/f.  Visible light has a wavelength range from ~400 nm to ~700 nm.  Violet light has a wavelength of ~400 nm, and a frequency of ~7.5*1014 Hz.  Red light has a wavelength of ~700 nm, and a frequency of ~4.3*1014 Hz." into google, and the correct website pops up as the first result.

Explanation:

I tried to link the website that I use to convert wavelengths and frequencies into types of light, but it deleted my answer, so I guess we're doing it this way. As for converting the wavelength to energy, the same principles apply as before:

Frequency: ν       Wavelength: λ       Energy: E       Speed of light: C (3.00e8)       Planck's Constant: h (6.626e-34)

ν -> λ    λ = C/ν

λ -> ν    ν = C/λ

For either of these equations, wavelength must be converted to meters or nanometers, depending on the equation.

For ν -> λ, after doing the equation, convert the wavelength into nanometers by dividing by 1e-9.

For converting λ -> ν, convert the wavelength into meters by multiplying by 1e-9.

For energy: E = hν = hc/λ

Answer:

An atom's electronegativity is affected by both its atomic number and the distance at which its valence electrons reside from the charged nucleus. The higher the associated electronegativity, the more an atom or a substituent group attracts electrons.

Explanation:

Hope this helps :)

Answer:

5.9e-5

Explanation:

12 Km / hour

Explanation:

using the formula

average speed =  ( where time is in hours )

40 min =  =  hour

speed = 8 ÷  = 8 ×  = 12 Km / hour

Answer:

12 Km / hour

Answer:

x100.

Explanation:

Na2CO3 (aq) + CaCl2(aq) → CaCO3 (s) + 2 NaCl (aq)

For example, if we use 2.00 g CaCl2 x 1 mole = 0.0180 mole CaCl2

111 g CaCl2

and mix it with 2.00 g Na2CO3 x 1 mole = 0.0189 mole Na2CO3

106 g.

AB + CD → CB + AD, where A and C are cations and B and

D are anions

Answer:

x100 this is the answer I didn't do explanation sorry for that

Answer:

A prefix

Explanation:

you're welcome

The covalent molecules named as,

So, option B is correct one.

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Mass spectrometry is the technique that measures the ratio of mass to charge. The spectrum of the element Sb is most likely represented by 121 and 123 atomic mass. Thus, option B is correct.

Mass spectrometry plots the spectrum representing the ratio of mass-to-charge by the signals generated by the ions. The spectrum estimates the mass and isotopes of the sample elements. They also determine the chemical properties and structures.

The spectrometry detects the isotopes that are stable and are known to have the same atomic number. It can be used to determine the isotopes of an element based on their peaks generated on the mass spectrum. Antimony has two stable isotopes with atomic masses 121 and 123.

Therefore, option B. the spectrum of the element Sb is most likely represented by Sb-121 and Sb-123.

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Answer:

The answer Is B. Chemical energy--> electromagnetic energy

Answer:

B. Chemical energy ---------> electromagnetic energy

D. Chemical energy  ---------> thermal energy

Explanation:

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