What is the systematic name of the following compound?
Li2S
Choose 1 answer:
А
Lithium sulfate
B В
Lithium sulfide
Dilithium sulfate
Dilithium sulfide

Answer:

More generally, astronomy studies everything that originates beyond Earth's atmosphere. Cosmology is a branch of astronomy that studies the universe as a whole. Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky.

Explanation:

The trick here is to realize the every sample of sodium bromide, regardless of its mass, will contain

22.34

%

sodium by mass.

This is true because sodium and bromide always combine in definite proportions, i.e. stable ratios by mass, to form sodium bromide.

Now, a

22.34

%

percent concentration by mass means that every

100 g

of sodium bromide will contain

22.34 g

of sodium and

100 g

−

22.34 g

=

77.66 g Br

Therefore, you can say that the mass ratio that exists between sodium and bromine in any sample of sodium bromide will be

22.34 g Na

77.66 g Br

=

22.34

77.66

You can thus use this definite proportion to say that a

5.69 g

sample of sodium bromide will contain

5.69

g NaBr

⋅

22.34 g Na

100

g NaBr

=

1.271 g Na

=

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

∣

∣

a

a

1.27 g Na

a

a

∣

∣

−−−−−−−−−−−−−

The answer is rounded to three sig figs.

You can use the known definite proportion to find the mass of bromide present in the sample

1.271

g NaBr

⋅

77.66 g Br

22.34

g NaBr

=

4.42 g Br

This checks out because

mass of NaBr sample



5.69 g

−

mass of Na



1.27 g

=

mass of Br



4.42 g

The answers to your questions are ;

a) The mass percentage of Na in the sample will be higher in the sample

b) The mass percentage of Na in the sample will be be lower in the sample

Given that:

Mass percentage of sodium contained in sodium Bromide = 22.34%

a) Determine if the mass percentage of Na will be higher or lower when sodium Bromide is contaminated with sodium chloride  

mass percentage of Na in sodium bromide

= ( mass of Na / mass of NaBr )*100

The mass of sodium in NaBr and NaCl is the same while the mass of Br is not same ( greater than ) as the mass of Cl.  hence when NaBr is contaminated with NaCl the total mass of  in percentage NaBr will decrease. and This decrease in mass of NaBr will lead to a decrease/lower mass percentage of Na in the sample

b) When NaBr is contaminated with NaI

The mass of Na is the same in NaBr and NaI while the mass of I is not the same ( greater than ) as the mass of Br, therefore the total mass will increase and the increase in the Total mass in percentage will lead to an increase/higher value of Na in the given sample.

hence the mass percentage of Na will decrease when NaBr is contaminated with NaCl while the mass percentage of Na will increase when NaBr is contaminated with NaI

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Answer:

[tex]\boxed {\boxed {\sf 928.8 \ grams}}[/tex]

Explanation:

Density is the mass per unit volume of a substance. The following formula is used for calculating density.

[tex]\rho= \frac{m}{v}[/tex]

We know the density of aluminum is 2.70 grams per milliliter. The mass is unknown, but we know the piece of aluminum has a volume of 344 milliliters.

Substitute these values into the formula.

[tex]2.70 \ g/mL = \frac {m}{344 \ mL}[/tex]

We are solving for the mass, so we must isolate the variable m. It is being divided by 344 milliliters. The inverse operation of division is multiplication. Multiply both sides of the equation by 344 mL.

[tex]344 \ mL *2.70 \ g/mL = \frac {m}{344 \ mL} * 344 \ mL[/tex]

[tex]344 \ mL *2.70 \ g/mL =m[/tex]

The units of milliliters cancel.

[tex]344 *2.70 \ g=m[/tex]

[tex]928.8 \ g =m[/tex]

The mass of the piece of aluminum is 928.8 grams.

Answer:

i hope this helps, also you might want to put it into your own words because this was directly from the answer key :)

Explanation:

Faustus Faustus is the protagonist of the play. He is a brilliant scholar who makes a deal with Lucifer to exchange his soul for magical power. He later regrets his decision, but it’s too late and his soul is carried away to hell.

Mephastophilis Mephastophilis is a demon that Faustus calls upon to help him with magic. He turns into Faustus's servant in his pact with the devil.

Valdes and Cornelius Valdes and Cornelius are friends of Faustus who teach him the art of black magic.

three scholars The three scholars are friends of Faustus who are concerned about his welfare.

Lucifer Lucifer (the devil) is Mephastophilis’s master. He makes a deal with Faustus.

Wagner Wagner is Faustus’s servant. He learns how to work magic from his master’s books.

clown The clown becomes Wagner's servant. He provides comic relief in the story.

good angel The good angel is a spirit that tries to get Faustus to repent.

evil angel The evil angel is a spirit that tempts Faustus to rebel against God and make a pact with the devil.

the pope The pope is the head of the Roman Catholic Church and symbolizes the religious beliefs that Faustus has abandoned.

horse-courser The horse-courser is a horse trader who purchases a horse from Faustus.

old man The old man is a mysterious figure who takes the place of the good and evil angels in the last scene of the play.

Answer:

1°C rise in temperature is equal to a rise of 59°F

Answer:

Hence 1℃ rise in temperature is equal to the rise in 59℉.

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Answer:

55/350

Explanation:

because the answer is in the middle of 50and 400

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Explanation:

It is the total mass of protons and neutrons in an individual atom or isotope. Since, Atomic Mass is total mass of protons and neutrons in an individual atom or isotope and not the actual weight of an Atom.

this means that it exists in the form of isotopes and is generally in fraction.

Answer:

2nd one

Explanation:

Big bang echo other ones make no sense.

The percentage abundance of  6Y is 0.102.

An Isotope refers to two or more atoms that has the same atomic number but different mass  numbers.

We have been informed from the question that the atomic mass of the element is 6.9412 amu.

Let the abundance of isotope 6Y be x

Let the abundance of isotope 7Y  be 1-x

Hence;

6.9412 = 6.015123x + 7.016005(1 - x)

6.9412 = 6.015123x + 7.016005 - 7.016005x

6.9412 - 7.016005 = 6.015123x - 7.016005x

-0.102 = -1x

x = -0.102/-1

x = 0.102

Hence the percentage abundance of isotope 6Y is 0.102.

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The percentage abundance of 6Y is 7.47%

Isotopy is the phenomenon whereby two or element have the same atomic number but different mass number due to the difference in their neutron number.

We'll begin the solving as follow:

Let A represent isotope 6Y

Let B represent isotope 7Y

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

Mass of A = 6.015123 amu

Mass of B = 7.016005 amu

Abundance of B (B₀) = (100 – A₀%

Relative Atomic mass of Y = 6.9412 amu

The abundance of 6Y can be obtained as follow:

[tex]RAM = \frac{MassA * A_{0} }{100} + \frac{MassB * B_{0} }{100}\\\\6.9412 = \frac{6.015123 * A_{0}}{100} + \frac{7.016005 (100 - A_{0})}{100}\\\\6.9412 = 0.06015123 A_{0} + \frac{701.6005 - 7.016005A_{0}}{100}\\\\6.9412 = 0.06015123 A_{0} + 7.016005 - 0.07016005A_{0}[/tex]

Collect like terms

[tex]6.9412 - 7.016005 = 0.06015123A_{0} - 0.07016005A_{0}\\-0.074805 = -0.01000882A_{0}[/tex]

Divide both side by –0.0100882

[tex]A_{0} = \frac{-0.074805}{-0.01000882}\\\\[/tex]

Therefore, the abundance of 6Y is 7.47%

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Answer: 50.7 moles

Explanation:

given mass/ molecular mass

= 50.7/1

=50.7

Answer:

[tex]\boxed {\boxed {\sf 25.1 \ mol \ H_2}}[/tex]

Explanation:

We are asked to calculate the number of moles in 50.7 grams of hydrogen gas. To do this, we will use the molar mass or the mass of 1 mole of a substance. These values are found on the Periodic Table because they are equivalent to the atomic masses, but the units are grams per mole instead of atomic mass units.

Look up the molar mass of hydrogen (H).

Note that we are given grams of hydrogen gas. This is a diatomic molecule with 2 hydrogen atoms. The formula is H₂. Multiply the molar mass by 2 to find hydrogen gas's molar mass.

Now we can convert using dimensional analysis. Set up a ratio using the molar mass.

[tex]\frac {2.016 \ g \ H_2}{1 \ mol \ H_2}[/tex]

We are converting 50.7 grams to moles, so we multiply the ratio by this value.

[tex]50.7 \ g \ H_2 *\frac {2.016 \ g \ H_2}{1 \ mol \ H_2}[/tex]

Flip the ratio so the units of grams of hydrogen gas cancel.

[tex]50.7 \ g \ H_2 *\frac{1 \ mol \ H_2} {2.016 \ g \ H_2}[/tex]

[tex]50.7 \ *\frac{1 \ mol \ H_2} {2.016 }[/tex]

[tex]\frac {50.7} {2.016 } \ mol \ H_2[/tex]

[tex]25.14880952 \ mol \ H_2[/tex]

The original value of grams (50.7) has 3 significant figures, so our answer must have the same. For the number we calculated, that is the tenths place. The 4 in the hundredth place to the right tells us to leave the 1 in the tenths place.

[tex]25.1 \ mol \ H_2[/tex]

50.7 grams of hydrogen gas is equal to approximately 25.1 moles of hydrogen gas.

Answer:

d. 20 protons and 22 neutrons

Atomic nuclei containing 20 protons and 22 neutrons. Thus, option D is correct.

An electron is defined as a subatomic particle which is charged negatively either bound to an atom or not it means free. The nucleus of an atom is made up of electron, proton and neutron. The electron is a basic particle and electron is not made of anything.

The nature of electron is free it means they are present freely in nature and consist of an atom.The main function of electron is that they play the role of negatively- charged component of an atom.

The electrons are primary source of current conducting and electrons number as well as atomic number of an element is always same or equal. There is no size of electron but the mass of electron is 9×10^-31.

Therefore, Atomic nuclei containing 20 protons and 22 neutrons. Thus, option D is correct.

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Answer:

Copper (Cu), chemical element, a reddish, extremely ductile metal of Group 11 (Ib) of the periodic table that is an unusually good conductor of electricity and heat. Copper is found in the free metallic state in nature.

Explanation:

hope this helps:)

Answer:

[tex]\boxed {\boxed {\sf 2.3 \ g/mL}}[/tex]

Explanation:

We are asked to find the density of a rock. Density is the substance's mass per unit volume. The formula for calculating density is:

[tex]\rho= \frac{m}{v}[/tex]

The mass of the rock is 23 grams. The volume was found using water displacement. A known amount of water was measured, the rock was added to the graduated cylinder, and the water level was recorded again. The volume is the difference between the final and initial water level. The graduated cylinder originally had 20 milliliters and the water rose to 30 milliliters.

Now we know the mass and the volume.

Substitute the values into the formula.

[tex]\rho= \frac{ 23 \ g }{30 \ mL}[/tex]

Divide.

[tex]\rho= 2.3 \ g/mL[/tex]

The density of the rock is 2.3 grams per milliliter.

Answer:

The metals are located on the left and the non-metals are located on the right.

Explanation:

Hope this helps :)

Answer:

There are three amino acids that have basic side chains at neutral pH. These are arginine (Arg), lysine (Lys), and histidine (His). Their side chains contain nitrogen and resemble ammonia, which is a base. Their pKa's are high enough that they tend to bind protons, gaining a positive charge in the process.

Answer :

arginine is basic amino acid because it's side chain group contains a full positive charge at the physiological pH. Histidine is also considered basic but it can have a positive or a neutral charge on its side chain group at the physiological pH

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Answer:

Magnetic separation

Explanation:

Sand is non-magnetic whereas iron fillings can be used as magnets. So, they can be separated by a method which uses a magnet for separating a mixture. Magnetic separation is the process which uses magnetic force for the extraction of magnetic material from a mixture.

through magnet

although not writable answer but for gk even a blow of wind shall do

Answer:

The correct answer is Science is objective, whereas pseudoscience is subjective. Pseudoscience includes beliefs, theories, or practices that have been or are considered scientific, but have no basis in scientific fact. This could mean they were disproved scientifically, can't be tested or lack evidence to support them.

Explanation:

hope its help

thank you

Transition metals are known to have incompletely filled d- orbitals. For this reason, they are commonly referred to as the d- block. Cu4+  is a d7 ion.

An ion is formed when electrons are lost from or gained in a neutral atom.

An ion is a positively or negatively charged chemical specie. Chemical species form ions by loss or gain of electrons.

An atom is neutral if it has equal number of protons and electrons. When an atom has lost electrons, it forms a positive ion.

Copper has electronic configuration; 1s2 2s2 2p6 3s2 3p6 4s2 3d9. When four electrons are lost, its electronic configuration now becomes;

1s2 2s2 2p6 3s2 3p6 3d7.

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Answer:

The correct answer is D

Explanation:

more protons in the nucleus cause an increase in effective nuclear charge ,

Answer:

It is a mixture of denatured alcohol, water, and agents added to make the alcohol unpalatable to drink.

Answer:

Molar mass of the diprotic acid is 424 grams

Explanation:

[hint: diprotic acid only contains 2 hydrogen protons]

Ionic equation:

[tex]{ \bf{2OH { }^{ - } _{(aq)} + 2H { }^{ + } _{(aq)}→ 2H _{2} O _{(l)} }}[/tex]

first, we get moles of potassium hydroxide in 28.94 ml :

[tex]{ \sf{1 \: l \: of \: KOH \: contains \: 0.3021 \: moles}} \\ { \sf{0.02894 \: l \: of \: KOH \: contain \: (0.02894 \times 0.3021) \: moles}} \\ { \underline{ = 0.008743 \: moles}}[/tex]

since mole ratio of diprotic acid : base is 2 : 2, moles are the same.

Therefore, moles of acid that reacted are 0.008743 moles.

[tex]{ \sf{0.008743 \: moles \: of \: acid \: weigh \: 3.7066 \: g}} \\ { \sf{1 \: mole \: of \: acid \: weighs \: ( \frac{1 \times 3.7066}{0.008743}) \: g }} \\ = { \underline{423.95 \: g \approx424 \: grams}}[/tex]

for the molar mass:

Explanation:

the atomic number is the number of protons in the atom

Answer:

Only one of these methods separates compontents based on size.

The answer is filiration and chromatography.

Explanation:

Answer:

837.9

Explanation:

Answer:  149.9 ml

Explanation:  Do as the formula suggests:  D = M/V

0.8 g/ml = 119.9 grams/V

V = (119.9 grams)/(0.8 grams/ml) = 212.8 ml

Note how the grams cancel and the ml moves to the top.

The  orbital is occupied by an electron with the quantum numbers n=3, l=2 will be 3d where n is orbit and l is band the d orbital have 5 degenerate orbitals.

Orbitals are the well defined circular paths into which electron revolve around the nucleus in 2D mostly denoted by K L M N etc and all of them will be circular in the shape and non directional as well.

Orbitals are the 3D space of the nucleus where the probability of finding the electron will always be greater or maximum denoted by s p d and f and having shapes like s orbital is spherical shaped p orbital is in some other shape.

Therefore, orbital is occupied by an electron with the quantum numbers n=3, l=2 will be 3d where n is orbit and l is orbital and the d orbital have 5 degenerate orbital's.

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