This is hard, isn't it? please help me though. PLEASE

Answer:

B. It's a physical change because the water and the salt kept their original properties.

Explanation:

Even though it tastes like salty water, the salt is still present, just in smaller molecules. It can be brought back so it is a physical change.

Answer:

c

Explanation:

Answer:

True

Explanation:

Bc why not? :)

Answer:

Covalent Bond

Explanation:

A covalent bond involves electrons being shared between atoms. The most stable state for an atom occurs when its valence electron shell is full, so atoms form covalent bonds, sharing their valence electrons, so that they achieve a more stable state by filling their valence electron shell.

Answer:

blue curve on edge :)

Explanation:

Answer:

Chlorine is in group 7A, so it has 7 valence electrons

The Lewis structure for the molecule NCl²⁻ with -2 charge is attached in the image below.

Lewis structures are also called as electron dot structures and can be drawn if the molecular formula of a compound is known. It provides information regarding the nature of bond and the position of atoms .

They are also capable of exhibiting the lone pair if any present in a molecule or compound.Lewis defined a base to be an electron pair donor and an acid to be an electron pair acceptor.

They are capable of reflecting electronic structure of elements and even the pairing of electrons . In the diagram, each dot represents an electron while a pair of dots represent a bond between the atoms.It helps in understanding the  bonding between the two atoms.

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Answer:

575 g

Explanation:

1 kg of sodium hydroxide is 1000/40=25 mol.

So 25 mol of sodium will be needed.

25 mol of sodium is 575 g.

According to the stoichiometry of the given chemical equation, 575 g s of sodium would be needed to produce 1.00 kg of sodium hydroxide.

Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.

A plus sign is present between reactants and products if they are more than one in any case and an arrow is present pointing towards the product side which indicates the direction of the reaction .There are coefficients present next to the chemical symbols and formulas .

The first chemical equation was put forth by Jean Beguin in 1615.By making use of chemical equations the direction of reaction ,state of reactants and products can be stated. In the chemical equations even the temperature to be maintained and catalyst can be mentioned.

46 g sodium gives 80 g sodium hydroxide, thus 1000 g sodium hydroxide requires 46×1000/80=575 g sodium.

Thus, 575 g s of sodium would be needed to produce 1.00 kg of sodium hydroxide.

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Answer:

Ca(OH)2 molecular weight. Molar mass of Ca(OH)2 = 74.09268 g/mol. This compound is also known as Calcium Hydroxide. Convert grams Ca(OH)2 to moles or moles Ca(OH)2 to grams. Molecular weight calculation: 40.078 + (15.9994 + 1.00794)*2 ››

Hey,

A) Let's first calculate the molar mass M of the molecule :

M(Ca(OH)₂) = M(Ca) + 2M(O) + 2M(H)

B) Let's deduct the corresponding mass m :

m = M x n

The mass of calcium hydroxide corresponding to this quantity of substance (in mol) is therefore 34 g.

Answer:

7.96g, 33.79%

Explanation:

I'll try my best to explain the entire process behind this question ;)

From the question, you can write the reaction

[tex]2H_2O(l)->2H_2(g)+O_2(g)[/tex]

Now, there are a few reasons it is like this. Oxygen is a diatomic element, meaning it doesn't and can't exist as just O. It exists as O₂. To balance, this, double the amount of water and hydrogen so there is an equal amount of  each element on both sides of the reaction (4 H's, 2 O's on the reactant side, and 4 H's, 2 O's on the product side).

From this we can get a mole-to-mole ratio.

Onto the stoichiometry. Our goal in this is to convert from grams of water to grams of hydrogen, and we do so with a mole to mole ratio.

[tex]71.0gH_2O*\frac{1molH_2O}{18.02g} *\frac{2molH_2}{2molH_2O}* \frac{2.02g}{1molH_2}\\\\ =7.96gH_2[/tex]

Basically, what I did was divide by water's molar mass to get moles of water, multiplied by the mole-to-mole ratio (2:2) to get moles of H2, and then multiplied by H2's molar mass to get what should be the amount of H2 produced by the reaction.

For percent yield, you can calculate it is such:

[tex]\frac{Actual}{Theoretical}*100[/tex]

Plug the numbers in:

[tex]\frac{2.69g}{7.96g}*100\\\\ =33.79%[/tex]

So, the percent yield is 33.79%

Answer:

Selenium trisulfide

Answer:

HCI

Explanation:

Hope this helps. :))))

Answer:

NaOH

Explanation:

Sodium hydroxide is the base in the acid-base reaction as all other acids and sodium chloride is salt and water is neutral.

According to the Arrhenius concept, base is defined as a substance which yields hydroxyl ions on dissociation.These ions react with the hydrogen ions of acids to produce salt in an acid-base reaction.

Bases have a pH higher than seven as they yield hydroxyl ions on dissociation.They are soapy in touch and have a bitter taste.According to the Lowry-Bronsted concept, base is defined as a substance which accepts protons .Base react violently with acids to produce salts .Aqueous solutions of bases can be used to conduct electricity .They can also be used as indicators in acid-base titrations.

They are used in the manufacture of soaps,paper, bleaching powder.Calcium hydroxide ,a base is used to clean sulfur dioxide gas while magnesium hydroxide can be used as an antacid to cure acidity.

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Answer:

sory Idont know Iwish you answer this question

When the ticket price was $15, a total of 180 people visited the art show as it denotes a point with most accuracy.

Accuracy  in terms of chemistry can be defined as to how close a measurement is to the true value.There are three types of accuracy:

1) Point accuracy-It means accuracy is present at that point of scale only.It does not give any information about the accuracy of the instrument.

2)Percentage of true value--It is the accuracy  which is determined by identifying accuracy of the instrument  and comparing it with the measured true value.

3)Percentage of scale range- It is the accuracy  which determines accuracy of the measurement.

Accuracy of percentage of scale range type as the measurements are to be made within a range where the sample has to be measured.

Accuracy in case of instruments  is neglected up  to ±0.5 percent.

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Answer:

17.86km/hr

Explanation:

Speed or velocity is calculated using the formula:

Speed (v) = distance (d) ÷ time (t)

According to the information given in this question;

Distance = 10km

Time = 33.6minutes = 33.6/60 = 0.56hours

Speed/velocity = 10/0.56

= 17.857

= 17.86km/hr

Answer:

0.297619048

Explanation:

distance= 10 km

time= 33.6 min

10/33.6

v= 0.297619048

or 0.29

Answer:

i dont know

Explanation:

ask your science teacher

Answer:

The electrons located between the two nuclei are bonding electrons. A hydrogen molecule forms from two hydrogen atoms, each with one electron in a 1 s orbital. The two hydrogen atoms are attracted to the same pair of electrons in the covalent bond. The bond is represented either as a pair of dots or as a solid line.

Answer:

True

Explanation:

It means the reaction is occuring.

Answer:

Radiometric dating, is called radioactive dating, is a technique used to determine the age of materials such as rocks. It is based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.

Explanation:

:)

The three ways in which travelers should be considerate when using public transport include the following:

This is the type of transport which is available to the general public such as trains, buses etc.

It is best to be considerate when using it by applying the following methods mentioned above to prevent disturbance and conflict.

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Answer:

crystal structure

Explanation:

Answer: Cs because its further to the right on the table, meaning its more reactive.

Explanation:

Answer:

Cs

Explanation:

This element is the farthest right, and lowest meaning that its reactivity is very high.

1. valence electrons and electronegativity

2. Both reactivity and electronegativity decrease down a group.

3. Electronegativity decreases down a group and reactivity increases down a group.

4. The number of valence electrons increases from left to right.

5. Cs

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Answer:

See explanation

Explanation:

In chemistry, the idea of "like dissolves like" is of utmost importance. A substance is only soluble in another with which it can effectively interact.

We must note that to be "soluble" means that the solute actually interacts effectively (dissolves) in the solvent.

However, vinegar is a polar substance while oil is a non polar substance hence the two can not effectively interact. That is, the vinegar can not dissolve in oil.

The two will separate into two phases upon standing. Therefore, the bottle of salad dressing made with oil and vinegar must be shaken in order to mix the two thoroughly before it is used.

Answer:

When the sweat hits the air, the air makes it evaporate (this means it turns from a liquid to a vapor). As the sweat evaporates off your skin, you cool down. Sweat is a great cooling system, but if you're sweating a lot on a hot day or after playing hard you could be losing too much water through your skin.

Explanation:

Hope it is helpful....

Answer:

HH and hh

Explanation:

they are the same

Explanation:

12 hours ago

El ácido sulfúrico H2SO4 es uno de los compuestos que se utiliza para la producción de fertilizantes como el nitrosulfato amónico. Si disponemos de 8 mL de H2SO4 al 37 %P/P (d=1,26 g /mL), los cuales se disolvieron hasta alcanzar un volumen de solución de 400 mL, con una densidad de 1,08 g/mL. (La densidad del soluto es corresponde a 1,83 g/cm³)

Answer:

C) It moves faster and collects more data

Explanation: