PLEASSE HELP gotta get the answers neowww, basically just match the letters with the things.

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Answer:

In the compond Mg(OH)_2, 20 atoms are present.

Explanation:

Answer:

See below

Explanation:

Helium belongs to group VIII of the periodic table "Noble gases". It has only 1 electronic shell and that too contains 2 electrons according to the accommodation of the shell. Hence, it's electronic shell is complete. This is the reason, Helium is chemically unreactive.

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Answer:

oxide

Explanation:

Answer:

wdym

Explanation:

hmm

Answer:

True.Explanation:

same system, heterogeneous nucleation will occur at less undercooling than homogeneous nucleation.

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As we know, Number of protons = Atomic Number

So,

And, Atomic mass = Number of protons + Number of Neutrons (N)

therefore ~

Number of Neutrons = 19

Oxidation- Reduction reaction

Answer:

I hope this will help

Explanation:

Copper is purified by electrolysis . Electricity is passed through solutions containing copper compounds, such as copper(II) sulfate. The anode (positive electrode ) is made from impure copper and the cathode (negative electrode) is made from pure copper.

All three elements  in the periodic table will for sure have characteristic of mass and volume.

An element  is defined as a substance which cannot be broken down further into any other substance. Each element is made up of its own type of atom which is characteristic of it's own. Due to this reason all elements are different from one another.

Elements can be classified as metals and non-metals. Metals are shiny and conduct electricity and are all solids at room temperature except mercury. Non-metals do not conduct electricity and are mostly gases at room temperature except carbon and sulfur.

The number of protons in the nucleus is the defining property of an element and is related to the atomic number.All atoms with same atomic number are atoms of same element.

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Answer:

Nitrite:

Nitrate:

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Answer: The difference between a physical reaction and a chemical reaction is composition. In a chemical reaction, there is a change in the composition of the substances in question; in a physical change there is a difference in the appearance, smell, or simple display of a sample of matter without a change in composition.

Explanation:

Answer:

4 4 8 4 is the balanced equation

Answer:

There are 1.9926 * 10 ^24 atoms.

Explanation:

M ( Mg ) = 80.45 g

We can find the molar mass of magnesium in the Periodic table:

M ( Mg ) = 24.31 g / mole

n = 80.45 g : 24.31 g/mole = 3.31 moles

N a ( Avogadro`s constant ) = 6.02 * 10 ^23

N = Na * n = 6.02 * 10 ^24 * 3.31 = 19.926 * 10 ^23

Answer: 4.123 x 10^22

Explanation:

The first step is to determine how many moles of sulfur hexafluoride (SF6) there are. To do this, you must take the mass of the SF6 (10g) and divide it by the molar mass (146.06).

[tex]10g * \frac{1 mol}{146.06 g}= 0.068465 mol[/tex]

Then you must use Avagadros number to find the number of molecules.

Avagadros number is the number of molecules in 1 mol of a substance, so a simple multiplication will do the trick.

[tex]0.068465mol * \frac{6.022 * 10^{23}}{1mol} = 4.123*10^{22}[/tex]

And that is your answer. There are 4.123 x 10^22 molecules of sulfur hexafluoride in 10g of it.

Answer:

Take 49.2-ml of 18.0 M H2SO4 stock solution and pour it into a 500-ml volumetric flask. Fill to the 500-ml line with distilled water to make 1.77M H2SO4 solution.

Explanation:

use the formula M1V1=M2V2

volume must be in liters(L)

[tex](1.77)(500 \times {10}^{ - 3} ) = (18)v2 \\ 0.885 = 18v2 \\ v2 = \frac{0.885}{18} \\ v2 = 0.04916[/tex]

0.04916L × 1000 = 49.16 ml = 49.2 ml

What is the position of alkali metals in the Modern periodic table.

They are placed in the IA group, which is the first column on the left side of the periodic table.

Alkali metals are placed on the first column (IA)

(lithium, sodium, potassium, rubidium, cesium, francium)

Propane has MSDS rating for flammability 4, thus the compound has been highly flammable. Thus, option C is correct.

The MSDS has been the Material Safety Data Sheet . It has been given for the compounds hazardous levels. The compounds have been checked on various parameters and ranked on the scale of 0 to 4.

The compounds being less value in the parameter has 0 value, while 4 has been the maximum value.

The MSDS rating for propane has been able to deliver the compound to be:

The compound has been less positive towards the health.

The compound has been highly flammable.

The compound has been least reactive.

Since, propane has MSDS rating 4 for flammability, the compound has been highly flammable. Thus, option C is correct.

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Answer:A) Highly corrosive but not highly flammable

Explanation:

right on edge :)

1. Genetic factors are those where the genetic condition of an individual is capable of increasing the probability of developing certain diseases.

Environmental factors include the diversity of environmental stresses such as population density, temperature, food and pollutants that impact human health.

Social factors are related to the interaction of groups through culture, social class and family structure, which also have an effect on population health.

Pathogenic factors, on the other hand, are those transmitted by agents such as viruses, fungi, bacteria and protozoa, which colonize a host by adhering to cells and evading immunity, generating diseases.

2. The transmission of pathogens can occur in several ways, such as contact with bodily fluids from infected people, cross-transmission or through being spread through particles in the air.

3. We can prevent the transmission of pathogens through proper hygiene habits, healthy eating, vaccination against infectious diseases and avoid contact with other people if you have a communicable disease.

4. The environment can affect personal health through climate change, pollution and lack of infrastructure that lead to less access to quality food and basic health conditions.

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That is an ionic bond.

Explanation:

It has cations and anions

Answer:

abundance of the first isotope times the Mass of the first isotope

size and shape. only the appearance of the paper will have changed, but is reversible.

Answer:

A. Producing certain synthetic materials could have a greater environmental impact than disposing of them.

Explanation

I just did this question and got it right.

True statement for a nuclear reactions is that it changes the identity of the element.

Nuclear reactions are those reactions in which changes in the nucleus of atoms take place in the form of fission and fussion.

Hence identity of element changes.

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Answer:

Explanation:

Are there any awnser choices?

Answer:

1) actual yield - 2.675 g

Theoretical yield - 4.0539 g

2)a) 41.257 g

b) 0.6857moles

c) 23 g

Explanation:

1)

Theoretical yield is the mass of the product that can obtain from the equation, it is not practical.

Theoretical yield:

Mr of SiO2 - 60

Moles of SiO2 - 2.339/60 = 0.03898 moles

Mr of SiF4 - 104

Mass of SiF4 - 0.03898 * 104 = 4.05392 g

2)

a)

mr of B2H6 - 28

Moles of B2H6 - 36.1/28 = 1.2893 moles

Mr of O2 - 32

Mass of O2 - 32 * 1.2893 = 41.257 g

b)

Moles of B2H6 - 19.2/28 = 0.6857 moles

Stoichiometry 1:1 ratio between B2H6 and H2O

So moles of H2O is 0.6857

c) moles of O2 - 2/24(r.t.p) = 0.083 moles

Mass of B2H6 - 0.083 * 28 = 2.3 g