Stars are _____
for most of their lives.
A) stable
B) unstable
C) unpredictable

6.64×1000÷(78-25)×500=0.25 g/k

Answer:

6.64×1000÷(78-25)×500=0.25 g/k

Answer:

The statements that accurately  describe how the assumptions affects scientific thinking are;

People think that the Earth is flat, so they think that it is only safe to travel certain distances from a given location.

People think that the Earth is flat, so think that when the Sun sets, it does underneath the Earth

Explanation:

The proof that the Earth is round was made by the Greek philosopher, Aristotle, over 2,000 years ago, by observation of the change in the constellation of the stars as a person changes his position North or South

The initial belief was that the Earth is flat disc surrounded by water, while the it was believed that the shape of the Earth was that of a square with four mountains at the vertices that support the sky from falling.

Answer:

oxidation:Ti to Ti           Reduction:O2 toO2

Explanation:

oxidation loses electron while Reduction gains electron

[tex] \LARGE{ \boxed{ \red{ \rm{Answer}}}}[/tex]

☃️ Chemical formulae ➝ [tex]\sf{Ca_3(PO_4)_2}[/tex]

For solving this question, We need to know how to find moles of solution or any substance if a certain weight is given.

[tex] \boxed{ \sf{No. \: of \: moles = \frac{Given \: weight}{Molecular \: weight} }}[/tex]

Atomic weight of elements:

❍ Molecular weight of [tex]\sf{Ca_3(PO_4)_2}[/tex]

= 3 × 40 + 2 × 31 + 8 × 16

= 120 + 62 + 128

= 310 g/mol

❍ Given weight: 20 g

Then, no. of moles,

⇛ No. of moles = 20 g / 310 g mol‐¹

⇛ No. of moles = 0.0645 moles

⚘ No. of moles of Calcium phospate in the given weight = 0.0645 moles.

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Answer:

Explanation:

To find the number of moles in calcium phosphate we use the formula

[tex]n \: = \frac{m}{M} [/tex]

where

n is the number of moles

M is the molar mass

m is the mass of the substance

To find the number of moles we must first find the molar mass

Chemical formula for calcium phosphate is

Ca3( PO4)2

Ca = 40 , P = 31 , O = 16

So the Molar mass of calcium phosphate is

M( Ca3( PO4)2 ) = (20×3) + 2( 31 + (16×4)

= 60 + 2( 31 + 64)

= 60 + 2(95)

= 60 + 190

Molar mass of calcium phosphate =

250g/mol

Mass = 20 g

So we have

[tex]n = \frac{20g}{250g/mol} [/tex]

We have the final answer as

Hope this helps you

Answer:D. Is the correct answer

Explanation:

Following are the calculation of the lead (Pb) atoms:

Balanced reaction:  

[tex]\bold{3PbO+2NH_3\longrightarrow 3Pb+N2+3H2O}\\\\[/tex]

[tex]\bold{mol\ NH_3 \longrightarrow mol \ Pb \longrightarrow atoms \ Pb}[/tex]

Calculating the number of atoms in Pb that will be generated:

[tex]=5.38 \ mol \ NH_3 \times \frac{3\ mol\ Pb}{2 \ mol NH_3} \times \frac{6.022 \times 10^{23} \times pb}{1 \ mol \ pb}\\\\ = 4.86 \times 10^{24} \ atoms\ in \ Pb\\\\= 4.86 \times 10^{24} \ atoms \\[/tex]

Therefore, the answer is "Option D"

Learn more:

brainly.com/question/21092165

[tex] \LARGE{ \boxed{ \rm{ \purple{Required \: answer}}}}[/tex]

☃️ Chemical formulae ➝ [tex]\sf{CaCO_3}[/tex]

How to find?

For solving this question, We need to know how to find moles of solution or any substance if a certain weight is given.

[tex] \boxed{ \sf{No. \: of \: moles = \frac{given \: weight}{molecular \: weight} }}[/tex]

And, Then we need to find the number of molecules which can be found by:

[tex] \large{ \boxed{ \sf{no. \: of \: molecules = N_A \times no. \: of \: moles}}}[/tex]

Here, Na = Avagadro Number (6.022 × 10²³)

☀️ As it is a compund, We considered molecules. Then, we can predict the no. of atoms of elements in one molecule of compound and get the answer.

Solution:

Atomic weight of elements:

❍ Molecular weight of [tex]\sf{CaCO_3}[/tex]

= 40 + 12 + 3 × 16

= 52 + 48

= 100 g/mol

❍ Given weight: 10 g

Then, no. of moles,

⇛ No. of moles = 10 g / 100 g mol‐¹

⇛ No. of moles = 0.1 moles

☄ No. of moles of Calcium carbonate in the given weight = 0.1 moles

Finding no. of molecules,

⇛ No. of molecules of CaCO3 = 0.1 × 6.022 × 10²³

⇛ No. of molecules of CaCO3 = 6.022 × 10²²

Now,

Then, 6.022 × 10²² molecules will have,

= 3 × 6.022 × 10²² atoms of oxygen

= 18.022 × 10²² atoms of oxygen

In more scientific form,

= 1.8022 × 10²³ atoms of oxygen

☄ Hence, Final answer - 1.8022 × 10²³ atoms

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Explanation:

Divide the mass of chlorine by the molar mass of cobalt chloride, then multiply by 100.

Molar Mass of Cobalt Chloride.

Mass of Chlorine in Cobalt Chloride.

Percent Composition of Chlorine.

Answer:

A

Explanation:

Density: water>ice>methanol

Ice is lighter than methanol hence it is able to float on it. However, ice is denser than water hence it sinks.

Answer:

The answer is A.

Explanation:

The density of ice in methanol must be different from that in water.

Answer:

C

Explanation:

The reactions:

[tex] \mathrm{Mg(NO_3)_2 \longrightarrow MgO+ 2NO_2 +O_2}\\

\mathrm{Mg(OH)_2 \longrightarrow MgO + H_2O}\\

\mathrm{MgCO_3 \longrightarrow MgO +CO_2}[/tex]

Answer:

3 bonds

Explanation:

solve this by doing the lewis structure for CIO3

Answer:

3 bonds.

Explanation:

2 double bonds and one single bond.

Answer:

Usually you have V, for voltage, Ohms for resistance, and Coulombs for charge.

Explanation:

See the image attached :)

Answer:

formed by burns rises quickly hydorogen

[tex] H_2+\frac12O_2 \longrightarrow H_2O[/tex]

I don't think I need to name the product.

this reaction is very exothermic. so the gases and the flames are very hot, i.e. very lighter (hot air rises) than the normal air. so it rises quickly

[tex] \LARGE{ \boxed{ \purple{ \rm{Answer}}}}[/tex]

☃️ Chemical formulae ➝ [tex]\sf{I_2}[/tex]

How to find?

For solving this question, We need to know how to find moles of solution or any substance if a certain weight is given.

[tex] \boxed{ \sf{No. \: of \: moles = \frac{Given \: weight}{Molecular \: weight} }}[/tex]

Solution:

❍ Molecular weight of [tex]\sf{I_2}[/tex]

= 2 × 126.90

= 253.80

= 254 (approx.)

❍ Given weight: 12.7

Then, no. of moles,

⇛ No. of moles = 12.7 / 254

⇛ No. of moles = 0.05 moles

⚘ No. of moles of Iodine molecule in the given weight = 0.05 moles

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Answer:

Explanation:

To find the number of moles (n) we use the formula

[tex]n = \frac{m}{M} [/tex]

Where

n is the number of moles

m is the mass of the substance

M is the molar mass

To find the number of moles we must first find the molar mass

Since iodine is a diatomic molecule

M( I ) = 127 × 2 = 254 g/mol

Mass of iodine = 12.7 g

So the number of moles in 12.7 g of iodine is

[tex]n = \frac{12.7 \: g}{254 \: g/mol} [/tex]

We have the final answer as

Hope this helps you

Answer:

x contain 9 percent ofcalcium carbonaye

Answer:

Mg(s) + 2H⁺(aq) ⟶ Mg²⁺(aq) + H₂(g)  

Explanation:

A net ionic equation shows all the ionic substances as ions and shows the correct state of each substance.

B. is wrong. HCl ionizes in aqueous solution into H⁺ and Cl⁻.

C. is wrong. Mg²⁺ is not a solid. It is an aqueous ion.

D. is wrong. The equation needs 2H⁺(aq) to be balanced.

[tex] \LARGE{ \boxed{ \red{ \rm{Answer}}}}[/tex]

☃️ Chemical formulae ➝ [tex]\sf{Al_2(CO_3)_3}[/tex]

For solving this question, We need to know how to find moles of solution or any substance if a certain weight is given.

[tex] \boxed{ \sf{no. \: of \: moles = \frac{given \: weight}{molecular \: weight} }}[/tex]

❍ Molecular weight of [tex]\sf{Al_2(CO_3)_3}[/tex]

= 2 × 27 + 3 × 12 + 9 × 16

= 54 + 36 + 144

= 234

❍ Given weight: 10 g

Then, no. of moles,

⇛ No. of moles = 10 / 234

⇛ No. of moles = 0.0427 moles

⚘ No. of moles of Aluminium carbonate in the given weight = 0.0427 moles.

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Answer:

a

Explanation:

Activation energy is the minimum amount of energy that must be overcome before a reaction will proceed to product.

In the energy diagram, the thick line represent the uncatalyzed path while the broken line line indicates the catalyzed path.

In the diagram above, the letter between the reactant and the Peak of the diagram gives the activation energy. This letter is a.

Therefore, the activation energy for the uncatalyzed reaction is 'a'.

Answer:

I got 0.01 moles, hope this helps!

Answer:

tails of comets

the ionosphere

a neon sign

Explanation:

Answer:

1 mol

Explanation:

Given:

C(s) + H₂O(g) → CO(g) + H₂(g)

According to the given equation, we can say that 1 mol of steam( H₂O ) reacts with  1 mol of charcoal.

So, 1 mol of steam( H₂O ) is the correct answer.

Answer:

0.60 mol·L⁻¹  

Explanation:

Data:  

LiBr: c = 0.50 mol/L; V =300 mL

RbBr: c = 0.70 mol/L; V =300 mL

1. Calculate the moles of Br⁻ in each solution

(a) LiBr

[tex]\text{Moles} = \text{0.300 L} \times \dfrac{\text{0.50 mol}}{\text{1 L}} = \text{ 0.150 mol}[/tex]

(b) RbBr

[tex]\text{Moles} = \text{0.300 L} \times \dfrac{\text{0.70 mol}}{\text{1 L}} = \text{ 0.210 mol}[/tex]

2. Calculate the molar concentration of Br⁻

(a) Moles of Br⁻

n = 0.150 mol  + 0.210 mol = 0.360 mol

(b) Volume of solution

V = 300 mL + 300 mL = 600 mL = 0.600 L

(c) Molar concentration

[tex]c = \dfrac{\text{moles}}{\text{litres}} = \dfrac{\text{0.360 mol}}{\text{0.600 L}} = \textbf{0.60 mol/L}[/tex]

The concentration of Br ions in the resulting solution of LiBr and RbBr has been 0.6 M.

The addition of LiBr and RbBr has been dissociated into the equal moles of Li, Rb, and Br.

[tex]\rm LiBr\;\rightarrow\;Li^+\;+\;Br^-[/tex]

[tex]\rm RbBr\;\rightarrow\;Rb^+\;+\;Br^-[/tex]

Thus 1 mole of LiBr = 1 mole Br

1 mole RbBr = 1 mole Br.

The moles of LiBr in 0.5 M solution:

Molarity = [tex]\rm moles\;\times\;\dfrac{1000}{volume\;(ml)}[/tex]

0.5 = [tex]\rm moles\;\times\;\dfrac{1000}{300\;ml}[/tex]

Moles of LiBr = 0.15 mol

The moles of Br from LiBr = 0.15 mol.

The moles of RbBr in 0.7 M solution:

Molarity = [tex]\rm moles\;\times\;\dfrac{1000}{volume\;(ml)}[/tex]

0.7 = [tex]\rm moles\;\times\;\dfrac{1000}{300\;ml}[/tex]

Moles of RbBr = 0.21 mol

The moles of Br from RbBr = 0.21 mol.

The total moles of Br ions from LiBr and RbBr has been :

= 0.15 + 0.21

= 0.36 mol.

The total volume of the solution will be:

= 300 + 300 ml

= 600 ml.

The concentration of the Br ion has been:

Molarity = [tex]\rm moles\;\times\;\dfrac{1000}{volume\;(ml)}[/tex]

Molarity of Br ions =  [tex]\rm 0.36\;\times\;\dfrac{1000}{600\;ml}[/tex]

Molarity of Br ions = 0.6 M.

The concentration of Br ions in the resulting solution of LiBr and RbBr has been 0.6 M.

For more information about the concentration of the sample, refer to the link:

https://brainly.com/question/11804141

Answer:

pseudocience consists of statements, belief or practices that are claimed to be both scientific and factual but are incompatible with the scientific method.

         Errors

Answer:

A). The complementary shapes of an enzyme and a substrate.

Explanation:

The Lock-and-key mechanism was proposed by Emil Fischer for the first time and characterized as the metaphor which helps in elucidating the specificity of the enzymatic reactions. In this metaphor, the lock is described as the enzyme while 'key' is characterized as the substrate which the enzyme acts upon. If the key is not appropriately sized, it will not fit into the active site i.e. the keyhole of the lock or enzyme and reaction will not take place. Thus, option A is the correct answer.

Answer:

[tex]\boxed{\sf B. \ grams/mole}[/tex]

Explanation:

[tex]\sf The \ molar \ mass \ of \ a \ substance \ is \ the \ mass, \ in \ grams,\ per \ one \ mole.[/tex]

[tex]\displaystyle \sf \frac{grams}{mole}[/tex]

Answer:

B

Explanation:

Grams/mole is correct. Got right on test!

Answer:

d

Explanation:

The arrangement of electrons in an atom

Answer:

D. Arrangement of electrons in an atom.

Explanation:

K L M N O P Q

2 8 8 18 18 32 50

The path where electrons revolve is called orbits.

Hope his helps ;) ❤❤❤

Answer:

Explanation:

By simple distillation, we can separate tow miscible liquids having sufficient difference in their boiling points.

By fractional distillation, we can separate the mixture of two or more miscible liquids for which the difference in their boiling point is less than 25k

Simple distillation is done using an air condenser or water condenser.

Fractionating column is fitted in between the distillation flask and the condenser for the process.

Simple distillation eg: mixture of water and acetone

fractional distillation eg: crude oil

hope this helps

plz mark as brainliest!!!!!!

Answer:

Simple Distillation:

1)This method is used for the separation of components of a mixture containing two miscible liquids that boil without decomposition.

2)The components must have sufficient difference in their boiling points.

Fractional Distillation:

1)Fractional distillation process is used to separate a mixture of two or more miscible liquids.

2)If, the components have the difference in boiling points less than 25K .                                                                              

Answer:

AI + F2 = AIF3

Explanation:

Answer:

The molecular geometry of AlF3 is trigonal planar with a symmetric charge distribution on the central atom. Therefore this molecule is non-polar.

Answer

A is the answer