7th grade help me plzzzz

Answer:

true atoms of each elementary

Answer:

false

Explanation:

Answer:

Solution i think

Explanation:

Answer:

Mechanical

Explanation:

chemical

Explanation:

I took test 2020

Answer:

Explanation:

2NaNO₃ = 2NaNO₂ + O₂

NaNO₃    =     NaNO₂   +    1/2 O₂

- 468 kJ           -369 kJ           0  kJ

enthalpy of decomposition reaction

= - 369 - ( - 468 ) kJ

= 99 kJ / mol .      

Answer:

Approximately [tex]19.1\; \rm g[/tex].

Explanation:

The unit of concentration in this question is "[tex]\rm M[/tex]". That's equivalent to "[tex]\rm mol \cdot L^{-1}[/tex]" (moles per liter.) In other words:

[tex]c(\mathrm{MgSO_4}) = 2.68\; \rm M = 2.68\; \rm mol \cdot L^{-1}[/tex].

However, the unit of the volume of this solution is in milliliters. Convert that unit to liters:

[tex]\displaystyle V = 59.3\; \rm mL = 59.3 \; \rm mL \times \frac{1\; \rm L}{1000\; \rm mL} = 0.0593\; \rm L[/tex].

Calculate the number of moles of [tex]\rm MgSO_4[/tex] formula units required to make this solution:

[tex]\begin{aligned}n(\rm MgSO_4) &= c \cdot V \\ &= 2.68 \; \rm mol \cdot L^{-1} \times 0.0593\; \rm L \approx 0.159\; \rm mol \end{aligned}[/tex].

Look up the relative atomic mass data of [tex]\rm Mg[/tex], [tex]\rm S[/tex], and [tex]\rm O[/tex] on a modern periodic table:

Calculate the formula mass of [tex]\rm MgSO_4[/tex] using these values:

[tex]M(\mathrm{MgSO_4}) = 24.305 + 32.06 + 4 \times 15.999 \approx 120.361\; \rm g \cdot mol^{-1}[/tex].

Using this formula mass, calculate the mass of that (approximately) [tex]0.159\; \rm mol[/tex] of [tex]\rm MgSO_4[/tex] formula units:

[tex]\begin{aligned}m(\mathrm{MgSO_4}) &= n \cdot M \\&\approx 0.159 \; \rm mol \times 120.361 \; \rm g \cdot mol^{-1} \approx 19.1\; \rm g\end{aligned}[/tex].

Therefore, the mass of [tex]\rm MgSO_4[/tex] required to make this solution would be approximately [tex]19.1\; \rm g[/tex].

Answer:

Carbohydrates

Explanation:

Living things use carbohydrates as their main source of energy. The breakdown of sugars, such as glucose, supplies immediate energy for cell activities. Plants, some animals, and other organisms also use carbohydrates for structural purposes.

In comparing the chemistry of the amines with alcohols and ethers, we discover many classes of related compounds in which nitrogen assumes higher oxidation states, in contrast to limited oxidation states of oxygen. In this context, keep in mind that the oxidation state of elemental oxygen (O 2) and nitrogen (N 2) is defined as zero.

Answer:

-3  

Explanation:

Answer: It's D

Explanation:

Answer:

N, B, Ni

Explanation:

Answer:

Explanation:

Answer:

ON

Explanation:

Frictional force is a force that opposes the motion of body. It is because of friction that motion can be controlled and even walking is made possible.

Now, on a frictionless surface, there is no opposition to motion. Therefore, to keep the body moving there is no force required.

Answer: 0.025 moles of nitrogen gas are there in the sample.

Explanation:

According to ideal gas equation:

[tex]PV=nRT[/tex]

P = pressure of gas = 1.03 atm

V = Volume of gas = 568 ml = 0.568 L   (1L=1000ml)

n = number of moles  = ?

R = gas constant =[tex]0.0821Latm/Kmol[/tex]

T =temperature =[tex]279K[/tex]

[tex]n=\frac{PV}{RT}[/tex]

[tex]n=\frac{1.03atm\times 0.568L}{0.0821L atm/K mol\times 279K}=0.025moles[/tex]

0.025 moles of nitrogen gas are there in the sample.

Answer:

The answer is true

Explanation: Because The law of multiple proportions states that when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other element in a ratio of small, whole numbers.

Answer: Sulfuric Acid

Explanation: correct on edg

Answer:

Sulfuric Acid

Explanation:

correct on edg

The phosphate group of one nucleotide bonds covalently with the sugar molecule of the next nucleotide, and so on, forming a long polymer of nucleotide monomers. The sugar–phosphate groups line up in a “backbone” for each single strand of DNA, and the nucleotide bases stick out from this backbone. The carbon atoms of the five-carbon sugar are numbered clockwise from the oxygen as 1′, 2′, 3′, 4′, and 5′ (1′ is read as “one prime”). The phosphate group is attached to the 5′ carbon of one nucleotide and the 3′ carbon of the next nucleotide. In its natural state, each DNA molecule is actually composed of two single strands held together along their length with hydrogen bonds between the bases.

Answer:

Explanation:

The discovery that DNA is the prime genetic molecule, carrying all the hereditary information within chromosomes, immediately focused attention on its structure. It was hoped that knowledge

of the structure would reveal how DNA carries the genetic messages that are replicated when chromosomes divide to produce two identical copies of themselves. During the late 1940s and early 1950s, several research groups in the United States and in Europe engaged in serious efforts—both cooperative and rival—to understand how the atoms of DNA are linked together by covalent bonds and how the resulting molecules are arranged in three-dimensional space. Not surprisingly, there initially were fears that DNA might have very complicated and perhaps bizarre structures that differed radically from one gene to another. Great relief, if not general elation, was thus expressed when the fundamental DNA structure was found to be the double helix. It told us that all genes have roughly the same three-dimensional form and that the differences between two genes reside in the order and number of their four nucleotide building blocks along the complementary strands.

Now, some 50 years after the discovery of the double helix, this simple description of the genetic material remains true and has not had to be ap- preciably altered to accommodate new findings. Nevertheless, we have come to realize that the structure of DNA is not quite as uniform as was first thought. For example, the chromosome of some small viruses have single-stranded, not double-stranded, molecules. Moreover, the precise orientation of the base pairs varies slightly from base pair to base pair in a manner that is influenced by the local DNA sequence. Some DNA se- quences even permit the double helix to twist in the left-handed sense, as opposed to the right-handed sense originally formulated for DNA’s general structure. And while some DNA molecules are linear, others are circular. Still additional complexity comes from the supercoiling (further twisting) of the double helix, often around cores of DNA-binding proteins.

Likewise, we now realize that RNA, which at first glance appears to be very similar to DNA, has its own distinctive structural features. It is principally found as a single-stranded molecule. Yet by means of intra-strand base pairing, RNA exhibits extensive double-helical character and is capable of folding into a wealth of diverse tertiary structures. These structures are full of surprises, such as non-classical base pairs, base-backbone interactions, and knot-like configurations. Most remarkable of all, and of profound evolutionary significance, some RNA molecules are enzymes that carry out reactions that are at the core of information transfer from nucleic acid to protein.

Clearly, the structures of DNA and RNA are richer and more intricate than was at first appreciated. Indeed, there is no one generic structure for DNA and RNA. As we shall see in this chapter, there are in fact vari- ations on common themes of structure that arise from the unique physi- cal, chemical, and topological properties of the polynucleotide chain

a. The unit cell is the smallest group of atom which have overall symmetry of a crystal, and from which is the entire letters can be buled built up by repetition in 3 dimensions.

b. The volume(v) of the unit cell is equal to the cell edge length (a)cubed.

c. density of polonium is 9.32g/cm3.

Answer:

Kindly check the explanation.

Explanation:

NADH is oxidized anaerobic conditions by lactate dehydrogenase because in order to transform or change Pyruvate into Lactate it has to happen in an anaerobic condition that is where we hardly find oxygen(in the presence of no oxygen).

The chemical compound or say the enzyme known as lactate dehydrogenase gets its proton from NADH( in a REDOX type reaction). After getting the proton from NADH, it uses that to convert Pyruvate into Lactate.

NB: the conversion can also be done in aerobic condition but more ATP will be produced. With anaerobic condition, less ATO is produced and there is re-oxidation.

Answer:

7.812atm

Explanation:

Using Van der Waals equation, which goes as follows:

Pv = nRT

Where;

P is the pressure

V is the volume (4.635L)

n is the number of moles (1.475mol)

T is the temperature (299K)

R is the universal gas constant (0.082057 L atm mol-1K-1)

Pv = nRT

P = nRT/V

P = 1.475 × 0.0821 × 299/4.635

P = 36.2081/4.635

P = 7.812atm

If we add water to a concentrated acid, then the solution may boil very violently, splashing concentrated acid. If add acid to water, the solution that forms is very dilute and a small amount of heat is released.

When a strong acid is poured into water, it flows down the flask and mixes much better, so no boiling takes place. The addition of water to acid forms an extremely concentrated solution of acid initially. A large amount of heat is released and the solution may boil very violently, splashing concentrated acid out of the beaker and all this because the reaction is exothermic in nature.

The reason this takes place is due to a large amount of energy liberated in the hydration reaction of concentrated ions. Therefore, we add acid to water dropwise for the dilution with constant stirring and not water to acid directly.

If we add water to acid, then an exothermic reaction occurs and the solution may boil very violently. To form the dilute solution of any strong acid, you should add acid to water and the small amount of heat released is not sufficient to vaporize and spatter it.

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Answer:

Explanation:

M1V1=M2v2

M1=0.150M

M2=0.150M

V2=120*10^-3

V1=M2V2/M1

V1=0.150*120*10^-3/0.150

V1=0.12

0.12 mL volume of 0.150M 2M Li₂S solution is required to completely react with 120 mL of 0.150M Co(NO₃)₂ MCo(NO₃)₂.

With M1 and M2 representing the molarity of the solutions, expressed as mol/L or M, and V1 and V2 representing their respective volumes, this calculator may be used to calculate a missing number for the dilution equation.

A solution's concentration is determined by multiplying its volume by its molarity (M1V1 = M2V2) On both sides of the equation, the units should stay the same.

Here

M₁V₁=M₂V₂

M₁=0.150M

M₂=0.150M

V₂=120 × 10⁻³

V₁=M₂V₂/M₁

V₁=0.150 × 120 × 10⁻³/0.150

V₁=0.12.

Therefore, 0.12 mL volume of 0.150M 2M Li₂S solution is required to completely react with 120 mL of 0.150M Co(NO₃)₂ MCo(NO₃)₂.

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Answer:

2

Explanation:

BIonary bi means 2

i hope this helps :)

Answer:

632.7 secs

Explanation:

Equation of the reaction:

Tl^3+ + 3e ------> Tl

If 1F = 96500 C

Q= It

Where;

I= current

t= time

3× 96500 C deposited 204 g of Tl

0.868 × t deposited 0.387 g of Tl

3 × 96500 × 0.387 = 204 × 0.868 × t

t= 3 × 96500 × 0.387/ 204 × 0.868

t= 632.7 secs

The time required for a constant current of 0.868 A to deposit 0.387 g of Tl(III) as Tl(s) is 2689 s

We'll begin by calculating the quantity of electricity needed to deposit 0.387 g of Ti

Ti³⁺ + 3e —> Ti

Recall:

1 mole of Ti = 48 g

1 electron (e) = 96500 C

Thus,

3 electrons = 3 × 96500 = 289500 C

From the balanced equation above,

48 g of Ti was deposited by 289500 C of electricity.

Therefore,

0.387 g of Ti will be deposited by = (0.387 × 289500) / 48 = 2334.09375 C of electricity

Quantity of electricity (Q) = 2334.09375 C

Current (I) = 0.868 A

t = Q / I

t = 2334.09375 / 0.868

Therefore, the time required for the reaction is 2689 s

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Answer:

peer reveiw

Explanation:

Answer:

Peer review.

Explanation: Ask Edu

Answer: The percent yield of the reaction is 77.0 %

Explanation:

[tex]2Pb+O_2\rightarrow 2PbO[/tex]

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

[tex]\text{Number of moles of lead}=\frac{451.4g}{207.2g/mol}=2.18moles[/tex]

[tex]\text{Number of moles of lead oxide}=\frac{374.7g}{223.2g/mol}=1.68moles[/tex]

According to stoichiometry:

2 moles of [tex]Pb[/tex] produces = 2 moles of [tex]PbO_2[/tex]

2.18 moles of [tex]Pb[/tex] is produced by=[tex]\frac{2}{2}\times 2.18=2.18moles[/tex] of [tex]PbO_2[/tex]

Mass of [tex]PbO_2[/tex] =[tex]moles\times {\text {Molar mass}}=2.18\times 223.2g/mol=486.6[/tex]

percent yield =[tex]\frac{374.7g}{486.6g}\times 100=77.0\%[/tex]

Answer:

B) . six electrons in the triple bond of diatomic nitrogen

Explanation:

The three line in this Lewis dot structure represents the six electrons in the triple bond of diatomic nitrogen.

Nitrogen is made up of 7 electrons with 5 valence ones.

 A lewis structure is made up of the symbol of the element surrounded by dot to represent the valence electrons.

  In this nitrogen molecule, both species share  6 electrons. This makes each nitrogen atom isoelectronic with neon.

Answer:

The answer is Diffusion.

Answer:

Hypertonic

Explanation:

Answer:

1. a

Explanation:

2. c

Answer:

1 is A number two is C