CALCULATE SCIENTIFIC NOTATION (Add and Subtract)

1) 9 × 103 + 2.3 × 104



2) 15 × 102 + 5.2 × 105





3) 10 × 104 + 2.8 × 106





4) 7.0 × 103 + 8.6 × 104





5) 3.0 × 104 + 14.5 × 105





6) 8 x 104 – 2.7 x 102





7) 5.0 x 103 – 8.9 x 104





8) 7.0 x 103 – 8.20 x 102

Answer:

a) 0.30

Explanation:

Kc = [C] [D] / ([A] [B])

Set up an ICE table:

[tex]\left[\begin{array}{cccc}&Initial&Change&Equilibrium\\A&0.4&-x&0.4-x\\B&0.4&-x&0.4-x\\C&0&+x&x\\D&0&+x&x\end{array}\right][/tex]

Plug in values and solve:

9 = x² / (0.4 − x)²

3 = x / (0.4 − x)

1.2 − 3x = x

1.2 = 4x

x = 0.3

Answer:

Neutral

Explanation:

A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic. The pH scale is logarithmic and as a result, each whole pH value below 7 is ten times more acidic than the next higher value.

Answer:

I believe it is neutral.

Explanation:

Since higher than 7 pH is alkaline, and lower than 7 pH is acidic.

Answer:

200K

Explanation:

Pressure is directly proportional to temperature.

100=225

x=450

(100*450)/225=x

x=45000/225

x=200

Answer:

26.66kg

Explanation:

If a person has a mass of 80kg, then they will weigh 80kg x 9.8m/s^2 or 784 Newtons on the Earth. That same person would weigh 80kg x 9.8m/s^2/3 or 261.33 Newtons on Mars, which the person might think was 26.66 Kg (although he would be incorrect since his mass has not changed).

Answer:

4.81×10¹⁰ atoms.

Explanation:

We'll begin by converting 3.2 pg to Ca to grams (g). This can be obtained as follow:

1 pg = 1×10¯¹² g

Therefore,

3.2 pg = 3.2 pg × 1×10¯¹² g / 1 pg

3.2 pg = 3.2×10¯¹² g

Therefore, 3.2 pg is equivalent to 3.2×10¯¹² g

Next, we shall determine the number of mole in 3.2×10¯¹² g of Ca. This can be obtained as follow:

Mass of Ca = 3.2×10¯¹² g

Molar mass of Ca = 40.08 g/mol

Mole of ca=.?

Mole = mass /molar mass

Mole of Ca = 3.2×10¯¹² / 40.08

Mole of Ca = 7.98×10¯¹⁴ mole.

Finally, we shall determine the number of atoms present in 7.98×10¯¹⁴ mole of Ca. This can be obtained as illustrated below:

From Avogadro's hypothesis,

1 mole of Ca contains 6.02×10²³ atoms.

Therefore, 7.98×10¯¹⁴ mole of Ca will contain = 7.98×10¯¹⁴ × 6.02×10²³ = 4.81×10¹⁰ atoms.

Therefore, 3.2 pg of Ca contains 4.81×10¹⁰ atoms.

Answer:

[tex]Fe_3PO_4[/tex]

Explanation:

To do this, we find the moles of each element. We get around 0.155 moles of Fe, 0.051 moles of P, and 0.206 moles of O. We then divide each one by the smallest one (which is 0.051 moles of P). We then get 3 for Fe, 1 for P, and 4 for O. This correlates to the empirical formula of the compound.

The empirical formula for the compound is [tex]Fe_3PO_4[/tex] if a 13.58 g sample of a compound contains 8.67 g of iron, Fe, 1.60 g of phosphorus, P, and oxygen, O.

An empirical formula tells us the relative ratios of different atoms in a compound.

We need to calculate the number of moles:

Given data:

Mass of iron - 8.67 g

Mass of phosphorus -1.60 g

Mass of oxygen -3.31 g

Moles of iron - [tex]\frac{mass}{molar \;mass}[/tex]

Moles of iron - [tex]\frac{8.67 g}{56 g/mol}[/tex]

0.15 mole

Moles of phosphorus [tex]-\frac{mass}{molar \;mass}[/tex]

Moles of phosphorus -  [tex]\frac{1.60 g}{31 g/mol}[/tex]

0.051 moles

Moles of oxygen -[tex]\frac{mass}{molar \;mass}[/tex]

Moles of oxygen - [tex]\frac{3.31 g}{16 g/mol}[/tex]

0.20 moles

Dividing each mole using the smallest number that is divided by 0.051 moles.

Fe:P:O :: 3:1:4

The empirical formula for the compound is [tex]Fe_3PO_4[/tex].

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Answer:

it is organism the third one

Answer:

Left

Explanation:

Metals are located on the left of the periodic table, and nonmetals are located on the upper right. They are separated by a diagonal band of semimetals.

Answer: D. Plutonium-238 is the most stable isotope

Explanation:

Radioactivity is the process of unstable isotopes to stable isotopes by decay, by emitting certain particles (such as alpha (α), beta (β), gamma (γ) particles)

General formulas used in decay:

T = duration of decay

t 1/2 = half-life

N₀ = the number of initial radioactive atoms

Nt = the number of radioactive atoms left after decaying during T time

Half-life shows the time it takes for an atom to get half of its initial mass (to decay to half of its initial mass)

The longer the half-life indicates the stability of the atom

Half-life (hr) of isotopes :

Polonium-210  : 3,310

Uranium-237  : 162

Francium-227  : 0.04

Plutonium-238 : 768,000

The half-life value above shows that Plutonium-238 has the longest time, making it the most stable

The longer the half life of an isotope higher will be its stability. Here, among the given isotopes, plutonium - 238 has the greater half life. Hence it is the mist stable one.

Heavy unstable radioactive isotopes undergoes nuclear decay through the emission of charged particles such as alpha or beta. The unstable isotopes then converts to other stable nuclei or to isotopes with more half life.

Half life of a radioactive isotope is the time required to decay the half of initial amount of the isotope. It is inversely proportional to the decay constant of the nuclear decay.

Among the given isotopes, Pu-238 has the longer half life time. Longer half time means more time to get decayed by half then more stability. Thus, Pu-238 is the most stable one.

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Answer:

II and IV.

Explanation:

To know which option is correct, do the following:

Energy (E) and frequency (f) are related by the following equation:

E = hf

Where:

E is the energy.

h is the Planck's constant.

f is the frequency.

From the equation E = hf

Energy is directly proportional to the frequency. This implies that an increase in the frequency will also increase the energy and a decrease in the frequency will also decrease the energy.

Therefore, (II) in the question above is correct.

Velocity (v), wavelength (λ) and frequency (f) are related by the following equation:

v = λf

Divide both side by λ

f = v/λ

Thus, we can see clearly that the frequency is inversely proportional to the wavelength. This means that an increase in frequency will decrease the wavelength and a decrease in frequency will increase the wavelength.

Therefore, (IV) in question above is correct.

Thus, II and IV are the correct answers.

Answer : The net ionic equation will be,

[tex]3Sr^{2+}(aq)+2PO_4^{3-}(aq)\rightarrow Sr_3(PO_4)_2(s)[/tex]

Explanation :

In the net ionic equations, we are not include the spectator ions in the equations.

Spectator ions : The ions present on reactant and product side which do not participate in a reactions. The same ions present on both the sides.

The given balanced ionic equation will be,

[tex]3Sr(OH)_2(aq)+2Li_3​PO_4(aq)\rightarrow 6LiOH(aq)+Sr_3(PO_4)_2(s)[/tex]

The ionic equation in separated aqueous solution will be,

[tex]3Sr^{2+}(aq)+6OH^{-}(aq)+6Li^{+}(aq)+2PO_4^{3-}(aq)\rightarrow Sr_3(PO_4)_2(s)+6Li^+(aq)+6OH^{-}(aq)[/tex]

In this equation, [tex]Li^+\text{ and }OH^-[/tex] are the spectator ions.

By removing the spectator ions from the balanced ionic equation, we get the net ionic equation.

The net ionic equation will be,

[tex]3Sr^{2+}(aq)+2PO_4^{3-}(aq)\rightarrow Sr_3(PO_4)_2(s)[/tex]

The complete ionic equation for the reaction between aqueous solutions of strontium hydroxide and lithium phosphate is:

3Sr²⁺(aq) + 6OH¯(aq) + 6Li⁺(aq) + 2PO₄³¯(aq) —> Sr₃(PO₄)₂(s) + 6Li⁺(aq) + 6OH¯(aq)

The complete ionic equation is simply an equation showing all available entities including the spectator ions present in the solution.

With the above information in mind, we shall write the complete ionic equation for reaction between aqueous solutions of strontium hydroxide and lithium phosphate. This can be obtained as follow:

In solution, strontium hydroxide, Sr(OH)₂ and lithium phosphate, Li₃PO₄ will dissociate as follow:

Sr(OH)₂(aq) —> Sr²⁺(aq) + 2OH¯(aq)

Li₃PO₄(aq) —> 3Li⁺(aq) + PO₄³¯(aq)

The reaction will proceed as follow:

Sr(OH)₂(aq) + Li₃PO₄(aq) —>

Sr²⁺(aq) + 2OH¯(aq) + 3Li⁺(aq) + PO₄³¯(aq) —> Sr₃(PO₄)₂(s) + 3Li⁺(aq) + 2OH¯(aq)

Balance the equation by writing 3 before Sr²⁺, 6 before OH¯, 6 before Li⁺ and 2 before PO₄³¯, to obtain the complete ionic equation as shown:

3Sr²⁺(aq) + 6OH¯(aq) + 6Li⁺(aq) + 2PO₄³¯(aq) —> Sr₃(PO₄)₂(s) + 6Li⁺(aq) + 6OH¯(aq)

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Answer:

it will change its physical property from solid into liquid

Answer: I believe that it’ll be 284.45

Explanation:

May have to double check but I’m pretty sure that’s correct sorry if it’s not

Answer:

I cant see it clearly

Explanation:

:(

Answer:

We  have,

Initial volume is V  

1

​  

Initial temprature is T  

1

​  

=75  

0

C

Initial pressure is P  

1

​  

So, final temprature is T  

2

​  

=273+75=348K

V  

2

​  

=V  

1

​  

−  

100

15

​  

V  

1

​  

=  

100

85V  

1

​  

​  

Applying the gas formula,

T  

1

​  

P  

1

​  

V  

1

​  

​  

=  

T  

2

​  

P  

2

​  

V  

2

​  

​  

348

P  

1

​  

V  

1

​  

​  

=  

T  

2

​  

×100

2P  

1

​  

×85V  

1

​  

​  

T  

2

​  

=  

100

2×85×348

​  

T  

2

​  

=591.6K

Explanation:

de Broglie wavelength= h/mv

v=h/m x de Broglie wavelength

v= (6.626× 10^-34)/ (2347× 1.27 × 10^-38)

v= 22.229 m/s(according to Google scientific calculator)

am sorry I don't hv a calculator at hand

Answer:

45.0

Explanation:

Using the rules of rounding, we can round 44.981 to 45. We need that third sig fig though, so we add the trailing zero

The value 44.981 g to three significant figures is 45.0 g.

Significant figures, also known as significant digits, are the digits in a number that carries meaning in terms of precision and accuracy. They indicate the certainty or reliability of a measurement or calculated value.

To round the value 44.981 g to three significant figures, follow the rules for significant figures:

Identify the three most significant digits in the number. They are 4, 4, and 9.

Look at the digit immediately after the third significant digit. If it is 5 or greater, round up; if it is less than 5, round down.

In 44.981 g, the digit immediately after the third significant digit (9) is 8. Since 8 is greater than 5, round up.

Therefore, rounding 44.981 g to three significant figures gives us:

45.0 g.

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Answer:

A

Explanation:

Force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newtons and represented by the symbol F.

Answer:

The Celsius scale is currently defined by two different temperatures: absolute zero and the triple point of Vienna Standard Mean Ocean Water (VSMOW; specially purified water). Based on this, the relationship between Celsius and Kelvin is as follows: TCelsius=TKelvin−273.15 T Celsius = T Kelvin − 273.15 .

Answer:

3

Explanation:

Answer:

10

Explanation:

Answer:

collect more sunlight

Answer:

to collect more sunlight

Explanation:

I

go to CALIFORNIA VIRTUAL ACADEMY ONLINE SCHOOL WITH K12

Answer:

Tin(IV) Oxide + Dihydrogen = Tin + Water

Explanation:

wasn't ez

Answer:

Density of Radon is  5.44 g/.

Explanation:

Given data:

Temperature of gas = 100°C (273+100 = 373 K)

Pressure of gas = 0.75 atm

Density of gas = ?

Solution:

First of all we will derive the formula.

We know that,

PV = nRT

and

n = m/M    (m = mass, M = molar mass)

PV = (m/M) RT

PVM =  (m/M) RT ×M

PVM = mRT

PVM/V = mRT/V

PM = dRT            (m/V = d)

Now we will put the values in formula:

Molar mass of Radon is 222 g/mol .

0.75 atm ×222 g/mol = d× 0.0821 atm.L/mol.K ×373 K

166.5 atm.g/mol = d×30.62 atm.L/mol

d = 166.5 atm.g/mol / 30.62 atm.L/mol

d = 5.44 g/L

Answer:

it should be B. earths core is composed of iron and nickel, if not let me know.

Answer: B. Earth's core is composed of iron and nickel.

Explanation: The inner core is solid so C and D are incorrect and A is incorrect because the core isn't made of magnets so it has to be B.

Answer:

4740460000, or 4.74046*10^9

Explanation:

This is math i thnk

e means *10

[tex]5.63\cdot \:8.42\cdot \:10^{19-11}[/tex]

[tex]5.63\cdot \:8.42\cdot \:10^8[/tex]

[tex]10^8\cdot \:47.4046[/tex]'

<3

Red

ok so this is saying

5.63 x 10^19 * 8.42 x 10^-11   indicates a scientific notation

plug into your graphing calculator and you get 4740460000 but make it imto three sig figs so the answer is: 4.74 x 10^9

Answer:

HCN+CuSO4->H2SO4+Cu(CN)2

2,1,1,1

1.Add 2 to HCN it then becomes (H=2, C=2, N=2,) (had to add 2 cz on right side you had H2 in H2SO4)

2.1(nothing) cz on both sides we got 1Cu and 1SO4

3.1 cz again we have H2 on both sides and 1SO4 on both sides

4.1 cz we got 1Cu on both sides and 2C 2N on both sides (1st step)

Answer:

Bromine (BR2)

Explanation:

Cl2 + Br2 = ClBr

Answer:

- First: element.

- Second: Compound.

- Third: element.

- Fourth: Compound.

Explanation:

Hello.

In this case, since elements are composed the same atom and compounds are composed by two different atoms, we can see that:

- First: it is an element as each sphere seems to be the same.

- Second: It is a compound as two different type of spheres are shown, white and black, considering each sphere is a different element.

- Third: it is an element because the spheres are equal, in fact, it is a diatomic element as two atoms are joined per molecule.

- Fourth: It is a compound as well since each molecule has two colored spheres and one white sphere, meaning that it has two different atoms per molecule.

Best regards.!