which one of the following are pure substances : water,salt water,copper,brass,air,oxygen​

Answers

Answer 1

Answer:

Copper, Water, and Oxygen

Explanation:

Because they are compounds and compounds are pure substances <3

Answer 2

Answer: copper

Explanation: because all of the atoms that make up copper are copper i.e its not a compound or mixture. not made od molecules


Related Questions

A sample of 0.600 mol of a metal M reacts completely with excess fluorine to form 46.8 g of MF2.?
a) How many moles of F are in the sample of MF2 that forms? (1.20 mol F)
b) How many grams of M are in this sample of MF2?
c) What element is represented by the symbol M? (Ca)

Answers

Answer:

See Explanation

Explanation:

Given:

moles M = 0.600 mole

moles F = excess (for rxn stoichiometry)

Formula Weight (F.Wt.) of F = 19 grams/mole (from Periodic Table)

Yield in grams = 46.8 grams (assuming theoritical yield)

Rxn:         M          +        F₂       =>   MF₂

         0.600mol         Excess          0.600mol (1:1 rxn ratio for M:MF₂)

a. moles of F in MF₂ = 2(0.600) moles F = 1.2 moles F

b. mole weight MF₂ = 46.8g/0.600mol = 78g/mole

    F.Wt. MF₂ = F.Wt. M + 2(F.Wt. F)

     => mass M = F.Wt. M = [F.Wt. MF₂ - 2(F.Wt. F)] = 78g/mol. - 2(19g/mol.)

     = (78 - 38) grams/mole = 40 grams/mole

c. Calcium (Ca) has F.Wt. = 40 grams/mole (compared to Calcium on Periodic Table.

From the question, the metal is the limiting reactant and must be used to obtain the required results which are;

a) There are 1.20 mol F in MF2.

b) There are 40g of M in MF2.

c) M is calcium.

From the reaction equation;

M + F2 ----> MF2

Since the reaction is 1:1, 0.600 mol of MF2 is formed

Note that 1 mole of MF2 contains two moles of F and one mole of M

Hence, number of moles of F in MF2 = 2 *  0.600 mol = 1.20 mol F

Since 1 mole of M is contained in MF2, there are 0.600 moles of M in MF2.

If 1 mol of M forms 1 mole of MF2

And, 0.600 mol of M form 0.600 mol of MF2

Number of moles of MF2 = mass/molar mass

Number of moles of MF2 =  0.600 mol

Mass of MF2 formed = 46.8 g

Molar mass of MF2 = mass/Number of moles of MF2

Molar mass of MF2 = 46.8 g/0.600 mol

Molar mass of MF2 = 78 g/mol

Molar mass = Sum of Relative atomic mass of component atoms.

Hence;

78 = M + 2(19)

M = 78 - 2(19)

M = 40 g

The element must be calcium

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What is it called when instead of getting rid of a product you find another

use for the product?

Answers

Answer:

Recycling.

Explanation:

When instead of getting rid of a product you find another use for the product, it is called recycling.

Recycling can be defined as a process which typically involves gathering, processing and transformation of materials or products that would otherwise be gotten rid of as waste materials or trash into new products that could be used for another purpose.

Basically, the recycling process involves turning a trash or unwanted product into a treasure (new product) that is capable of serving another purpose.

For example, the crown cork of a bottle could be gathered and processed into art forms that can be used for decorations.

Rocks are classified on the basis of

Answers

Answer:

Rocks are classified according to characteristics such as mineral and chemical composition, permeability, texture of the constituent particles, and particle size. This transformation produces three general classes of rock: igneous, sedimentary and metamorphic. Those three classes are subdivided into many groups.

Explanation:

Move the red warning icon to focus of the earthquake.

Move the green location icon to the epicenter of the earthquake.

Move the blue star icon to the fault.

Answers

Answer:

Red goes in the spiky yellow box. Green goes where the red circles are. Blue goes in the small yellow box that is pointing to the line.

Explanation:

The focus of an earthquake is where it starts in the earth. The epicenter is the part directly above the focus on the surface. The fault is the part where the earth's crust splits.

Which food dyes in the diagram on the right only contain one colour?
( Science, Chromatography )​

Answers

Colored dyes are really bad for you but I drink them anyways

Molten zinc chloride can be electrolysed.
Describe how this experiment can be carried out in a laboratory, explaining how the products of this electrolysis are formed.


(6) marks

Answers

Answer: The products of electrolysis are Zn(l) and [tex]Cl_2[/tex] gas

Explanation:

Electrolysis of a subastance is breaking it into its constituents by the action of electrical current.  

In the electrolysis of molten zinc chloride, zinc metal is produced at the cathode which is a negative electrode and chlorine gas produces as the anode which is a positive electrode.

[tex]ZnCl_2(l)\rightarrow Zn^{2+}+2Cl^-[/tex]

At anode : [tex]2Cl^-(l)\rightarrow 2e^-+Cl_2(g)[/tex]

At cathode : [tex]Zn^{2+}(l)+2e^-\rightarrow Zn(l)[/tex]

Jane is sitting in the family car. Her mother is driving her from their house to the library. Jane waves as she passes her friend Marina. Which of the following is not moving with respect to Jane?
A. Marina
B. The family car
C.The library
D. Jane’s house

Answers

Answer:

B) The family car

Explanation:

I hope this helps :)

For most substances the density of a solid form is slightly greater than the density of liquid form water however is different it is slightly less dense in the solid form than it is in liquid form compare water in the solid form with neon argon in oxygen and proposal reason why solid water is less dense liquid water

Answers

Answer:

Answer: When water freezes, water molecules form a crystalline structure maintained by hydrogen bonding. Solid water, or ice, is less dense than liquid water. Ice is less dense than water because the orientation of hydrogen bonds causes molecules to push farther apart, which lowers the density.

Explanation:

Is snow organic or inorganic?

Answers

Answer:

snow is made up of a variety of mostly organic matter, including dead or dying animals and phytoplankton, protists, fecal matter, sand, and other inorganic dust.

Explanation:

I hope I helped!!

Plz mark me brainliest it would really make my day!

Answer:

I think its organic unless we are talking about this snow storm then no

2. How many moles are there in 20 grams of Carbon?

Answers

Answer:

1.6666666666666 is the ans bcz in each mole there r 12 grams of carbon so the ans is goingtobe 20÷12

According to the mole concept, there are 1.66 moles in 20 grams of carbon.

What is a mole?

Mole is defined as the unit of amount of substance . It is the quantity measure of amount of substance of how many elementary particles are present in a given substance.

It is defined as exactly 6.022×10²³ elementary entities. The elementary entity can be a molecule, atom ion depending on the type of substance. Amount of elementary entities in a mole is called as Avogadro's number.

It is widely used in chemistry as a suitable way for expressing amounts of reactants and products.For the practical purposes, mass of one mole of compound in grams is approximately equal to mass of one molecule of compound measured in Daltons. Molar mass has units of gram per mole . In case of molecules, where molar mass  in grams present in one mole  of atoms is its atomic mass.

Number of moles is calculated as, mass/molar mass, thus on substitution , number of moles=20/12=1.66 moles.

Thus, there are 1.66 moles in 20  grams of carbon.

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. Which state of matter has a defined volume but no defined shape?
HELPPPP PLEASE FAST

Answers

Answer:

liquid

Explanation:

it's not plasma, solid, or gas

so I think liquid

The answer would be A liquid

This is the chemical formula for Chormium (III) nitrate Cr(NO3)3Calculate the mass percent of nitrogen in chromium(III) nitrate.

Answers

Answer:

The percent composition for nitrogen in chromium(III) nitrate is 6%.

Explanation:

The mass percent of nitrogen in chromium(III) nitrate is 17.655%.

Calculation,

Molar mass of one oxygen = 16 g

molar mass of nine oxygen = 9 × 16 g = 144 g

molar mass of one nitrogen atom = 14 g

molar mass of three nitrogen atom = 3 × 14 g = 42 g

molar mass of one chromium atom = 51.99 g

molar mass of chromium (III) nitrate molecule = 144 g + 42 g + 51.99 g = 237.99 g

Mass percent of nitrogen = mass of three nitrogen atom× 100 /mass of chromium(III)nitrate

Mass percent of nitrogen = 42 g/237.99 g × 100 = 17.655%

What is mass percentage?

The percentage of the mass of the element or solute divided by the mass of the compound or solute is called mass percentage

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At room temperature, CsF is expected to be:______.
a. a soft solid.
b. a conducting solid.
c. a gas.
d. a brittle solid.
e. a liquid.

Answers

Answer:

d. a brittle solid.

Explanation:

Hello!

In this case, since cesium fluoride is widely known as an ionic compound due to the large electronegativity difference, it is possible to discard a. due to its crystalline structure, b. because conducting solids are metals, c. because ionic compounds are not likely to be gases and e. because even when it is soluble in water, the problem is not referring to an aqueous solution; therefore, the answer is d. a brittle solid.

Best regards!

When drawing a Bohr model for Sulfur, how many energy levels will you
draw?
5
4
3
2.

Answers

Answer:

3

Explanation:

2,8,6

5. Why is picric acid and tannic acid used in the treatment of burns?

Answers

Picric acid has antiseptic and astringent properties. For medical use it is incorporated in a surface anesthetic ointment or solution and in burn ointments. Picric acid is a much stronger acid than phenol; it decomposes carbonates and may be titrated with bases.

Excess silver(I) nitrate was added to a 8.500 g mixture containing some amount of barium chloride, and 7.123 g of silver chloride was obtained. The unbalanced equation is
AgNO3 + BaCl2(aq) --> Ba(NO3)2(aq) + AgCl(s).
What is the mass% of BaCl2 in the mixture?

Answers

Answer:

60.88%

Explanation:

The balanced equation of the reaction is given as;

2 AgNO3 (aq) + BaCl2 (aq) → 2 AgCl (s) + Ba(NO3)2 (aq)

Since AgNO3 is in excess, the limiting reactant is BaCl2. From the reaction;

1 mol of BaCl2 produces 2 mol of AgCl

Converting to masses;

Mass = Number of mol * Molar mass

BaCl2;

Mass = 1 * 208.23 g/mol = 208.23 g

AgCl;

Mass = 2 * 143.32 g/mol = 286.64 g

208.23 g BaCl2 produces 286.64 g of AgCl

x g BaCl2 produces 7.123 g of AgCl

Solving for x;

x = 7.123 * 208.23 / 286.64 = 5.1745 g

Mass percent = Mass / Total mass of Mixture  * 100

Mass Percent = 5.1745 / 8.500 = 0.6088 * 100 = 60.88%

How many CaF are in a 1.7x10^25 please I need help fast!!

Answers

Answer:

28 mol CaF

General Formulas and Concepts:

Math

Pre-Algebra

Order of Operations: BPEMDAS

Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to Right

Chemistry

Atomic Structure

Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Stoichiometry

Using Dimensional AnalysisExplanation:

Step 1: Define

[Given] 1.7 × 10²⁵ molecules CaF

[Solve] moles CaF

Step 2: Identify Conversions

Avogadro's Number

Step 3: Convert

[DA] Set up:                                                                                                          [tex]\displaystyle 1.7 \cdot 10^{25} \ molecules \ CaF(\frac{1 \ mol \ CaF}{6.022 \cdot 10^{23} \ molecules \ CaF})[/tex][DA] Multiply/Divide [Cancel out units]:                                                         [tex]\displaystyle 28.2298 \ moles \ CaF[/tex]

Step 4: Check

Follow sig fig rules and round. We are given 2 sig figs.

28.2298 mol CaF ≈ 28 mol CaF

Question 2 2 points)
Which of the atoms shown has an atomic number of 42
1
2
4
7

Answers

Answer:

4 is the answer

Explanation:

i am not sure for this question

Help! I’ll give brainliest if u get it right!

Answers

Answer:

That is the Atomic mass

Explanation:

The element symbol is S, Element name is sulfur, and

Atomic number is 16

You dissolve 0.64 g of potassium chloride (KCl) in 725 ml of water.
What is the molarity of the solution?
(From the periodic table: 1 mol K = 39.10 g; 1 mol Cl = 35.453 g)
Enter the value rounded to three decimal places with no units
Will give BRAINLEST

Answers

Answer:

0.012 M

Explanation:

Step 1: Given and required data

Mass of KCl (m): 0.64 gVolume of water (V): 725 mL (We will assume it is equal to the volume of the solution)Molar mass of KCl (M): 74.553 g/mol

Step 2: Calculate the moles (n) of solute (KCl)

We will use the following expression.

n = m/M = 0.64 g / (74.553 g/mol) = 8.6 × 10⁻³ mol

Step 3: Calculate the molar concentration (C) of the solution

The molarity is equal to the moles of solute divided by the liters of solution.

C = 8.6 × 10⁻³ mol/0.725 L = 0.012 M

Where did the magma and sediment that formed the rock of the Great Plains and the Rocky
Mountains come from?
Which claim do you think is more likely to be true?
Claim 1: The sediment that formed the Great Plains came from the rock of the Rocky
Mountains.
Claim 2: The magma that formed the Rocky Mountains came from the rock of the Great Plains.

Answers

Answer:

1

Explanation seems right

The magma and sediments formed in the great plains are came from the rocks of the rocky mountains. Therefore, claim 1 is correct.

What is sedimentation?

Sedimentation is the geographical process of accumulation or deposition of the minerals and organic particles from the earth's surface is called sedimentation. This process results in the formation of sedimentary rocks.

Weathering or erosion of rocks by wind, water or other chemicals leads to the geological debris which then move to other places  deposits somewhere.

Rocks in the rocky mountains undergo erosion and the mass movements created by wind or water leads to the sedimentation of these rocky solids to other places. The rocks in the Great planes are reached there by the mass movement of the rocks of rocky mountains. Hence, claim 1 is correct.

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What type of reaction
the following chemical reaction?
2C2H4O2 → C4H6O3 + H2O

Answers

This type of chemical reaction is Decomposition

If the mercury in a manometer raises 30.0 millimeters due to a change in pressure, what is the corresponding change in pressure in atm?

Answers

Answer:

0.03947 atm

Explanation:

The relationship between mmHg and atm is given as;

1 atm = 760 mmHg

x atm = 30 mmHg

Upon solving for x;

x * 760 = 30 * 1

x = 30 / 760 = 0.03947 atm

3. Which state of matter has a defined shape?
HELP FAST

Answers

Answer:

Solid state of matter has a definite shape

The answer to this is solids!

Measurements show that the enthalpy of a mixture of gaseous reactants increases by 319kJ during a certain chemical reaction, which is carried out at a constant pressure. Furthermore, by carefully monitoring the volume change it is determined that 92kJ of work is done on the mixture during the reaction. Calculate the change of energy of the gas mixture during the reaction in kJ.

Answers

Answer:

the change in energy of the gas mixture during the reaction is 227Kj

Explanation:

THIS IS THE COMPLETE QUESTION BELOW

Measurements show that the enthalpy of a mixture of gaseous reactants increases by 319kJ during a certain chemical reaction, which is carried out at a constant pressure. Furthermore, by carefully monitoring the volume change it is determined that -92kJ of work is done on the mixture during the reaction. Calculate the change of energy of the gas mixture during the reaction in kJ.

From thermodynamics

ΔE= q + w

Where w= workdone on the system or by the system

q= heat added or remove

ΔE= change in the internal energy

q=+ 319kJ ( absorbed heat is + ve

w= -92kJ

If we substitute the given values,

ΔE= 319 + (-92)= 227 Kj

With the increase in enthalpy and there is absorbed heat, hence the reaction is an endothermic reaction.

Both magnetic fields and electric fields can exert a force true or false?

Answers

Answer:

false

Explanation:

An electric field may do work on a charged particle, while a magnetic field does no work.

A 0.90 g of hydrogen chloride (HCl) is dissolved in water to make 5.0 L of solution. What is the pH of the resulting hydrochloric acid solution?
Express the pH numerically to two decimal places.
0.50g of sodium hydroxide (NaOH) pellets are dissolved in water to make 4.0L of solution. What is the pH of this solution?
Express the pH numerically to two decimal places.

Answers

Answer:

Explanation:

Mol weight of HCl = 36.5

.90 g of HCl = .90 / 36.5 mole = .02465 mole

HCl      =    H⁺        +      Cl⁻

1 mole     1 mole

1 mole of HCl gives 1 mole of H⁺

.02465 mole of HCl will give .02465 mole of H⁺

.02465 mole of H⁺ in 5 litre soln

concentration of H⁺ =  .02465 / 5 = 4.93 x 10⁻³ M

pH = - log ( 4.93 x 10⁻³ )

= 3 - log 4.93

= 3 - .693

= 2.307

= 2.31

NaOH :

Mol weight of NaOH  = 40

.50 g of HCl = .50 / 40 mole = .0125 mole

NaOH     =    Na⁺        +      OH⁻

1 mole     1 mole

1 mole of NaOH gives 1 mole of OH⁻

.0125 mole of NaOH will give .0125 mole of OH⁻

.0125 mole of OH⁻ in 4 litre soln

concentration of OH⁻ =  .0125 / 4 = 3.125 x 10⁻³ M

pOH = - log ( 3.125 x 10⁻³ )

= 3 - log 3.125

= 3 - .495

= 2.505

pH = 14 - pOH

= 14 - 2.505

= 11.495 .

= 11.50

Iron-59 which is used to diagnose anaemia has a half life of 45days, what fraction of it is left in 90 days

Answers

Answer:

0.25 of the original

Explanation:

(0.5)^(90/45)

The fraction of iron-59 after 90 days is 0.25.

Iron-59 decays following first-order kinetics. Given the half-life ([tex]t_{1/2}[/tex]) of 45 days, we can calculate the rate constant (k) using the following expression.

[tex]k = \frac{ln2}{t_{1/2}} =\frac{ln2}{45day} = 0.015 d^{-1}[/tex]

For first-order kinetics, we can find the fraction of Fe ([Fe]/[Fe]₀) after and an elapsed time (t) of 90 days, using the following equation.

[tex]\frac{[Fe]}{[Fe]_0} =e^{-k \times t } = e^{-0.015 d^{-1} \times 90 d } \approx 0,25[/tex]

The fraction of iron-59 after 90 days is 0.25.

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What do atoms make up

Answers

atoms make upthey make up oxygen

If a solution containing 24.0 g of a substance reacts by first-order kinetics, how many grams remain after three half-lives?

Answers

Answer:

3.0g remain

Explanation:

The half-life is defined as the time required for a reactant to decrease its concentration in exactly the half of the initial amount of reactant. Having this in mind:

In one half-life, the mass will be:

24.0g / 2 = 12.0g

In two half-lifes:

12.0g / 2 = 6.0g

And in three half-lifes, the mass that remain is:

6.0g / 2 =

3.0g remain
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