help pls this is physical science (9th grade )

Answer:

As a skydiver falls, he accelerates downwards, gaining speed with each second. The increase in speed is accompanied by an increase in air resistance (as observed in the animation below). This force of air resistance counters the force of gravity. As the skydiver falls faster and faster, the amount of air resistance increases more and more until it approaches the magnitude of the force of gravity. Once the force of air resistance is as large as the force of gravity, a balance of forces is attained and the skydiver no longer accelerates. The skydiver is said to have reached a terminal velocity.

Answer:

wait are you talking about the bottom question??

Answer:

The nucleus of an atom is positively charged.

Explanation:

The nucleus of an atom is positively charged because :

The nucleus is a small dense region at the center of the atom. It consists of a positive protons and neutral neutrons. so, It has an overall positive charged.

Answer:

355.2 grams

Explanation:

m = M×n= (40 + 2(16+1))×4.8= 355.2 (g)

answer:

d

Explanation:

sun 109 million miles

2 star trillion of miles

Answer:

Estuaries are bodies of water where rivers meet the sea or a large lake. Rivers spread out and slow when they meet the sea, creating unique conditions that are not found elsewhere. They provide homes for diverse wildlife, including popular fish species.

The 17th and 18th i think.. If by non-metal you mean no metal I think Its the 17th and 18th

hope this could help a bit.

Answer:

Approximately [tex]0.11823\; \rm g[/tex] in total for the five tablets.

(Approximately [tex]2.3646 \times 10^{-2}\; \rm g[/tex] per tablet.)

Explanation:

The relative atomic mass of an element is the ratio between:

The definition of moles ensures that the relative atomic mass of an element is approximately numerically equal to the mass (measured in grams) of one mole of the atoms of this element.

The question states that the relative atomic mass [tex]A_{\rm r}[/tex] of iron is [tex]56[/tex]. In other words, the mass of one mole of iron [tex]\rm Fe[/tex] atoms would be approximately [tex]56\; \rm g[/tex].

The question is asking for the mass of some amount of [tex]\rm Fe^{2+}[/tex] ions. Each [tex]\rm Fe^{2+}\![/tex] ion contains two fewer electrons than a neutral [tex]\rm Fe[/tex] atom. Hence, [tex]4.2225 \times 10^{4}\; \rm mol[/tex] of [tex]\rm Fe^{2+} \![/tex] ions might be lighter than the same number of [tex]\rm Fe \![/tex] atoms by a very small extent: The mass of one mole of electrons is approximately [tex]5 \times 10^{-4}\; \rm g[/tex], much smaller than the mass of the same number of [tex]\!\rm Fe[/tex] atoms (approximately [tex]56\; \rm g[/tex].)

Estimate the mass of these [tex]4.2225 \times 10^{4}\; \rm mol[/tex] of [tex]\rm Fe^{2+}[/tex] ions using the mass of the same number of [tex]\rm Fe[/tex] atoms:

[tex]\begin{aligned}&m({\rm Fe^{2+}}) \\ &\approx m({\rm Fe}) \\ &\approx 4.2225 \times 10^{-4}\; \rm mol \\ &\quad\quad \times 56\; \rm g \cdot mol^{-1} \\ &\approx 2.3646 \times 10^{-2}\; \rm g \end{aligned}[/tex].

Five of these tablets would contain approximately [tex]5 \times 2.3646 \times 10^{-2}\; \rm g \approx 0.11823\; \rm g[/tex] of [tex]\rm Fe^{2+}[/tex] ions.

Answer:

endothermic

Explanation:

more energy is being released and heat is being required to do the process.

A) Since both are carbons with the only difference in the number of neutrons,

They are called Isotopes

B) Carbon - 12 has 6 protons and 6 neutrons, while Carbon-13 has 6 protons and 7 neutrons,

Therefore Carbon-12 and Carbon-13 have the same number of protons

C) Carbon - 12 has 6 protons and 6 neutrons, while Carbon-13 has 6 protons and 7 neutrons,

Therefore Carbon-12 and Carbon-13 has different numbers of neutrons

D) Sorry i don't know any uses of Carbon-12 and Carbon-13, you might have to research to get it.

E or F) Sodium 23 has 12 neutrons and 11 electrons, because its mass number 23, atomic number is 11 and since protons and electrons count is same, the number of neutrons = mass number - atomic number = 23 - 11 = 12 neutrons

Happy to help :)

If you need any more help, feel free to ask

The most likely to take place when a solid is placed in a liquid at room temperature ( i.e. 20°C ) is ; ( A )  A chemical reaction

Although your question lacks the required diagram a general answer is provided within the scope of your question

When a solid at 20°C is placed inside a liquid also at 20°C  in the laboratory the emergence of gas bubbles shows that there has been a chemical change between the solid and liquid reactant ( i.e. a chemical reaction has taken place ).

Hence we can conclude that what is most likely to have taken place in this situation is a Chemical reaction.

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Answer:

323 K

Explanation:

To convert Celcius to kelvin first you need to remember this equation:

C + 273 = K (K = kelvin and C = celsius)

Next, you substitute with what you have given:

50 + 273 = K

Solve the equation by adding 50 and 273

k = 323

Answer: a

Explanation:

Bc I just did it and yeah

Answer:

It should be A. I've never heard of freezing of sediments

Answer: (D) environmental chemistry

Explanation:

The environmental chemistry is branch of chemistry would study how pollution effects marine life. option D is correct.

Environmental chemistry is the study of the biochemical and chemical processes that occur in natural places like in forest, water bodies in air in soil and related to animals too.

Environmental chemistry is wide range of studies than air, water, soil, and chemicals. This also gives the brief account about the marine life with studying the life cycle of marine animals and plants too.

Therefore, environmental chemistry is branch of chemistry would study how pollution effects marine life. option D is correct.

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Answer: The standard potential is  -0.141 V

Explanation:

To calculate the Gibbs free energy for given value of equilibrium constant we use the relation:

[tex]\Delta G=-RTlnK[/tex]

where,

= standard Gibbs free energy = ?

R = Gas constant = 8.314 J/Kmol

T = temperature = 298 K

K = equilibrium constant =

Putting values in above equation, we get:

[tex]\Delta G=40853J[/tex]

Also [tex]\Delta G=-nFE^0[/tex]

where n = no of electrons gained or lost = 3

F = Faradays constant = 96500 C

[tex]E^0[/tex] = standard potential = ?

[tex]40853=3\times 96500\times E^0[/tex]

[tex]E^0=-0.141V[/tex]

Thus the standard potential is -0.141 V

Answer:

A. 21 J

Explanation:

Your temperature change is 10 degrees Celsius, or 10 Kelvin, it makes no difference either way.

Cp = 2.06 J/g•K

Multiply by the temperature change to just get J/g

2.06 J/g•K • 10 K = 20.6 J/g ≈ 21 J/g

21 J is the energy change per gram of ice when an iceberg composed of pure water, cp = 2.06 J/(g·K) which is heated from 25°C to 15°C. So, the correct option is A.

Heat is defined as the energy that is transferred from one body to another as a result of a difference in temperature, when two bodies at different temperatures are brought together, the energy transferred is that of the hotter body which flows towards the colder body.

In this case, according to the equation for the calculation of the heat during a heating process

[tex]Q= mC (T_f- T_i)[/tex]

It is possible to calculate mass per gram of ice by dividing both sides by removing m from the equation, we plug in the given specific heat and final and initial temperatures to get:

[tex]Q= 2.06 \frac{J}{g degree C} [-15 Degree C- (-25 Degree C][/tex]

[tex]Q= 20.6\frac{J}{g}[/tex] which is equals to 21° C

21 J is the energy change per gram of ice when an iceberg composed of pure water, cp = 2.06 J/(g·K) which is heated from 25°C to 15°C.

Therefore, the correct option is A.

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Answer:

I think it's a

Explanation:

not sure hssjkskaakakskksskksqoqkakskzksjsj

Answer: The answer is, D) Burning.

Explanation: Some moderator removed my last answer because someone reported it.

Answer: The limiting reactant is Na

Explanation:

Answer:

Becuase they can go through mountains and hills, they curve of of those.

Answer:

orange

Explanation:

Answer:

I have no idea

Explanation:

Answer:

2

Explanation:

The balanced chemical equation for this reaction is:

2Na + K2S → 2K + Na2S

Meaning the coefficient for potassium (K) is 2.

Answer:

2 / 1 => 2 / 1