Help please, take a screenshot who will answer will be brainiest.

Answer:

The energy levels or electron shells of an atom.

Answer:

Each ring represents a different energy level for the electrons. Each ring has a maximum number of electrons that it can hold. The first (inner) ring can only hold two electrons, the second level can hold eight, the third can hold 18 and the fourth holds 32.

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Answer:

Reaction time tests can be used to assess an individual's hand-eye coordination. One test involves catching a 1 metre ruler and measuring the distance, d in metres, that the ruler travelled before being caught. The reaction time t seconds is then calculated using the formula: = √2d/9.8

An observer in one of those galaxies see the other galaxy moving away at 400000 km/s.

Relative velocity is the velocity of an object with respect to another object, that is the time rate of change of relative position of one object with respect to another object.

Since two galaxy are moving in opposite directions with a velocity of 200,000 km/s. Hence the relative velocity between the two galaxies is 400000 km/s (200000 + 200000)

Therefore an observer in one of those galaxies see the other galaxy moving away at 400000 km/s.

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Answer:

D 400,000km/s

Explanation:

Answer: Place a piece of white paper under the analyte flask throughout the titration

Explanation:

The end point of titration can be made easy by the use of indicators. But we have to be keenly observe for each drop from the burette because, the colour change will be sudden for a drop.

Titration is an analytical technique used to determine the unknown concentration using a standard reagent of known concentration. The standard reagent of known concentration is called titrant and the  one to be determined is called analyte.

Usually analyte is taken in a conical flask and titrant in a burette. The end point of titration is the point at which the reaction is completed in perfect stoichiometry.

In acid-base titrations, the indicators used having different colors in different pH. Hence, the indicator in the analyte will change in color when the acidity of the medium changes. We have to observe keenly for the color change because it happens for any drop.

The adding of titrant from the burette must be dropwise and thus we can get a time to notice the sudden colour change of indicator.

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Answer:

4

Explanation:

cuz pure substance contain one type of atom,molecule,or cpd.

2 is true but it have wrong grammar,if it contain only one type it must be^^molecule^^

Answer:

O-H

Explanation:

It is polar covalent bond, because the hydrogen atom has electronegativity about 2.6, and the oxygen atom, electronegativity about 3.6. When the difference in electronegativity of the atoms is between 0.4 and 1.7, the result is a polar covalent bond.

Answer:

Explanation:

Pencils are though formed of wood that acts as a bad conductor of electricity, quite strangely pencils can be electrically charged.

Here pencils have non-metal carbons present in its graphite tip and this makes the pencils charged.

When this pencil is held near the water of the tap, the hydrogen ions get attracted and thereby the water gets attracted to the pencil.

Water, however, is an excellent conductor of electricity and therefore water and electricity are a dangerous combination.

Answer:

18

At STP, 22.4 liters of a gas forms one mole that is 6.023×10

23

molecules.

Volume of CO

2

in 1 litre of air =

100

0.03

×1 L

∴ No. of molecules of CO

2

=

22.4

6.023×10

23

×

100

0.03

=8.066×10

18

Explanation:

I guess it's this

[tex]\\ \sf\longmapsto PV=nRT[/tex]

[tex]\\ \sf\longmapsto n=\dfrac{PV}{RT}[/tex]

[tex]\\ \sf\longmapsto n=\dfrac{772(20)}{8.314(273)}[/tex]

[tex]\\ \sf\longmapsto n=\dfrac{15440}{2269.722}[/tex]

[tex]\\ \sf\longmapsto n=6.8mol[/tex]

Answer:

One arrow is positioned in each box according to Hund's Rule which tells us to maximise the number of unpaired electrons in orbitals of the same subshell, and, to give those electrons the same "spin" (parallel spin).

Explanation:

Answer:

mark me brainlest

Explanation:

Electronegativity values generally increase from left to right across the periodic table. Electronegativities generally decrease from top to bottom of a group. The highest electronegativity value is for fluorine.

Answer:

       "Electronegativity increases as you move from left to right across a period because the number of charges on the nucleus increases." (sstudy30 on Quizlet)

Explanation:

    It explains itself haha!

Have a nice day!

    I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)

- Heather

Explanation:

after learning more about the position and would

Answer:

In chemistry: a pure substance consists only of one element or one compound. a mixture consists of two or more different substances, not chemically joined together.

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Answer:

Explanation:

They play a very important part. The geometry is not a straight line. It is an angle over 90 which means that the molecule has the same general shape as a boomerang. The two hydrogens and the 2 lone electron pairs try to get away as far as possible from each other. The actual shape results in a tetrahedron shape. But the two hydrogens and 1 oxygen actually look like the aforementioned boomerang.

This problem is referring to an anhydrous salt that is derive from a hydrated Epson salt (magnesium sulfate hydrate) and the atom economy is required. However, not enough information is provided, yet we can use the attached file as a reference to provide a methodology of calculation.

To begin with, we need to calculate the [tex]x[/tex] which refers to the degree of hydration of the salt, so that we use the mass before and after heating the sample to figure out the grams and subsequently moles of water that are in there:

[tex]m_w=3.648g-1.782g=1.866g\\\\n_w=0.103molH_2O[/tex]

Next, since 1.782g corresponds to the anhydrous salt, we calculate the moles in such a amount:

[tex]1.782gMgSO_4*\frac{1molMgSO_4}{120.4gMgSO_4}=0.0148mol[/tex]

Then, we divide the moles of water by those of the anhydrous salt to calculte [tex]x[/tex]:

[tex]x=\frac{0.103mol}{0.0148mol} =6.96=7[/tex]

This means the formula of the hydrate is:

[tex]MgSO_4\ 7H_2O[/tex]

Finally, for the atom economy we just divide the molar mass of the anhydrous salt by that of the hydrate:

[tex]A.E=\frac{120.4g/mol}{246.47g/mol} *100\%\\\\A.E=48.8\%[/tex]

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An ionic bond is formed through the transfer of one or more valence electrons, typically from a metal to a non-metal, which produces a cation and an anion that are bound together by an attractive electrostatic force.

Answer:

Group 17

Explanation:

Group 16 of nonmetals will react with alkaline earth metals to form a compound in a 1 : 1 ratio. Therefore, option (b) is correct.

Alkaline earth metals or Group 2 includes six elements which are Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra).

This group contains smooth, silver metals with a less metallic character than group 1.  All alkaline earth metals have two valence electrons, giving a valency of 2. These metals easily lose electrons to form compounds via ionic bonds and become more stable.

The valency of calcium is 2 and the valency of the elements of group 16 is also 2. Therefore they can combine 1 : 1 ratio to form a neutral compound.

Ca²⁺    +   O²⁻   →  CaO

Therefore, the nonmetals of group 16 will react with alkaline earth metal.

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Water has relatively strong hydrogen bonds holding the molecules together but CO2 has only dispersion forces acting as intermolecular forces. The weaker intermolecular forces explains why CO2 is a gas whereas H2O is a liquid at room temperature

P_4O_8

How?

Let's learn how to create name of compound from its name.

Look below for root words

Hence formula of the compound is P4O8

Answer:

Paracetamol

Formula

C8H9NO2

Answer:

200 m^3

Explanation:

1000m³ of Carbon dioxide is required.

Propane is a type of hydrocarbon that is made up of a single carbon-carbon bond.

Propane burns in oxygen completely in a combustion reaction to produce carbondioxide and water.

The balance equation of combustion of propane gas is:

C3H8(g)+5O2(g)→3CO2(g)+4H2O(g).

But noncombustibility of propane is the incomplete combustion of propane which occurs in absence or insufficient oxygen supply.

The balanced equation for noncombustibility of propane is:

2C3H8 + 9O2 → 4CO2 + 2CO + 8H2O

2 moles of propane = 4 moles of CO2

CO21 mole of propane = 2 moles of CO2 (4moles/2moles)

Therefore 500cm³ of propane = 2 × 500

= 1000cm³

Therefore, 1000m³ of Carbon dioxide is required to ensure the noncombustibility of a 500-cubic-meter compartment filled with propane vapor

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[tex]2\text{Cr(NO}_3\text{)}_3} + 3\text{CuCl}_2 \longrightarrow 2\text{CrCl}_3 + 3\text{Cu(NO}_3\text{)}_2[/tex]

In this exercise we want to calculate the amount of moles, so this is going to be:

[tex](4.6)(10^{-3}) \ mols \ CO_2[/tex]

Knowing that Henry's law is given by:

[tex]C = KHP[/tex]

Where constants are given by:

Before we can find the concentration of CO2 (and hence the moles of CO2), we first need to find its partial pressure.  We look up the vapor pressure of water at 25º and find it to be 0.03 atm.  Since the total pressure is equal to 0.1 atm, this mean the partial pressure of:

[tex]CO_2 = 0.1 \ atm - 0.03 \ atm = 0.07 \ atm[/tex]

Now using Henry's law, we find the concentration:

[tex]C = (0.033)*( 0.07) = (2.31)*(10^{-3})[/tex]

Converting to moles of CO2, we have:

[tex](2.31)*(10^{-3})*( 2) = (4.6)*(10^{-3})[/tex]

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Answer:

O b

Explanation:

high compressibility is not the property of metal.

Answer:

Similar: both processes of cell division; both processes take place in the nucleus of the cell

Different: mitosis divides into 2, meiosis divides into 4; one is the division of body cells and the other is of specifically sex cells

Explanation:

https://byjus.com/biology/mitosis-and-meiosis/

^ this has more info!

Answer:

Test for carbon dioxide gas.

The reaction between baking soda and citric acid will form sodium ions, citric acid ions, carbon dioxide gas, and water. So all you have to do is add the gas produced (by gas displacement method or something) and test whether the gas is carbon dioxide, with lime water or other methods like hydrogencarbonate indicator. Hope this helped!

Explanation:

Answer:

depends on amount, but the reaction's endothermic (meaning its cold, absorbs heat from surroundings)

I hope it helps.

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Metals have tendency to loose electrons in order to get noble gas configuration, therefore they loose electrons to form Cations (positively charged ions)

for example ~ Sodium forms Na+

And

Non - metals have tendency to gain electrons in order to attain noble gas configuration , hence they gain electron from somewhere and bears a negative charge forming Anion.

for example ~ Chlorine forms Cl-