How did chemists change Mendeleev's periodic table in the early 1900s?

Answer:

C. read the label on the container

Explanation:

What information is found in an SDS? Check all that apply.

A. the identification of the chemical

C. the chemical and physical properties of the substance

D. the first-aid measures to take if an accident occurs involving the chemical

Answer:

C

Explanation:

just did it

Answer:

"The elements are arranged in seven horizontal rows, called periods or series, and 18 vertical columns, called groups."

Explanation:

I GIVE OUT FREE POINTS

Answer:

uh yeah I think so technically

Answer:

no

Explanation:

Answer:

Explanation:

1 is true

2 is false

3 is true

4 is true

5 is false

That is what I got from researching.

Only about 3% of the water in the Earth is fresh water and about 75 % of the fresh water on Earth is frozen in ice sheets.  

• The most vital element present on the Earth is water. All the living beings are dependent on it.  

• Water is present in the majority of the Earth, however, of this only 3% of the water is freshwater, the rest is saline and undrinkable.  

• Of this 3%, the 75 percent of the freshwater is present in the form of ice and glaciers in the polar region.  

• The remaining 24 percent is the groundwater and the rest 1 percent includes the waters of rivers, lakes, and ponds.  

• The prime source of usable freshwater is present in the trapped form in the ice and glaciers.  

Thus, the correct statements are 1st and 3rd.

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Answer: D. An increase in entropy

Explanation:

Entropy is the measure of randomness or disorder of a system. If a system moves from  an disordered arrangement to an ordered arrangement, the entropy is said to increase and vice versa.

For a reaction to be spontaneous, the enthalpy of the solution must decrease and the entropy must increase.

To overcome a positive enthalpy of solution and allow a solid  solute to dissolve in water, an increase in entropy would make the reaction spontaneous as the system would move to a more disordered state.

Answer:In the first law, an object will not change its motion unless a force acts on it. In the second law, the force on an object is equal to its mass times its acceleration. In the third law, when two objects interact, they apply forces to each other of equal magnitude and opposite direction

Explanation:

Answer:

EEEEEeeEEeEEEEEEEeEEEEEEEEEE

Explanation:

e

Answer Electromagnetic waves are used to transmit long/short/FM wavelength radio waves, and TV/telephone/wireless signals or energies. They are also responsible for transmitting energy in the form of microwaves, infrared radiation (IR), visible light (VIS), ultraviolet light (UV), X-rays, and gamma rays.

Explanation:

Electromagnetic waves are important in society today because they are used to "transmit long/short/FM wavelength radio waves, and TV/telephone/wireless signals or energies. They are also responsible for transmitting energy in the form of microwaves, infrared radiation (IR), visible light (VIS), ultraviolet light (UV), X-rays, and gamma rays."

Answer: B) must be available for workers to review

Explanation:

WHMIS is a Canadian program which gives information to the employers about the workers knowledge about hazardous materials that are used in the workplace. It is ensured that the worker labelled the hazardous material at the workplace, material safety data sheet should be created to supplement the label, and worker's education program for learning the safety precautions is also conducted.

The material safety data sheets are created by the employers and their is no expiry date for such data for workers instead they receive a next recommended training date for participating in the training and avail another certification after the completion of first year.

Answer:

metamorphic

Explanation:

when one rock changes another rock the rock that got changed is now metamorphic

Answer:

V₂ = 238.05 L

Explanation:

Given data:

Final volume = ?

Initial volume = 13.40 L

Initial pressure = 1.51 atm

Final pressure = 65 mmHg ( 65/760 = 0.085 atm)

Solution:

The given problem will be solved through the Boyle's law,

"The volume of given amount of gas is inversely proportional to its pressure by keeping the temperature and number of moles constant"

Mathematical expression:

P₁V₁ = P₂V₂

P₁ = Initial pressure

V₁ = initial volume

P₂ = final pressure

V₂ = final volume  

Now we will put the values in formula,

P₁V₁ = P₂V₂

1.51 atm × 13.40 L = 0.085 atm × V₂

V₂ = 1.51 atm × 13.40 L /  0.085 atm

V₂ = 238.05 L

Answer:

I believe what your looking for is Nitrogen disulfide

Explanation:

Hope this helps (:

Answer: A decomposition reaction occurs when one reactant breaks down into two or more products.

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Answer:

Molecular formula = C₄H₁₂O₂

Explanation:

Given data:

Percentage of hydrogen = 13.80%

Percentage of carbon = 51.02%

Percentage of oxygen = 35.18%

Molecular formula = ?

Solution:

Number of gram atoms of H = 13.80 / 1.01 = 13.6

Number of gram atoms of O = 35.18 / 16 = 2.2

Number of gram atoms of C = 51.02 / 12 = 4.25

Atomic ratio:

            C                      :      H             :         O

           4.25/2.2           :     13.6/2.2     :       2.2/2.2

            2                      :        6          :        1

C : H : O = 2 : 6 : 1

Empirical formula is C₂H₆O.

Molecular formula:

Molecular formula = n (empirical formula)

n = molar mass of compound / empirical formula mass

Empirical formula mass = C₂H₆O = 46 g/mol

n = 88 / 46

n = 2

Molecular formula = n (empirical formula)

Molecular formula = 2 (C₂H₆O)

Molecular formula = C₄H₁₂O₂

121 mol CH₄

Math

Pre-Algebra

Order of Operations: BPEMDAS

Chemistry

Organic

Atomic Structure

Step 1: Define

7.31 × 10²⁵ molecules CH₄

Step 2: Identify Conversions

Avogadro's Number

Step 3: Convert

[tex]\displaystyle 7.31 \cdot 10^{25} \ molecules \ CH_4(\frac{1 \ mol \ CH_4}{6.022 \cdot 10^{23} \ molecules \ CH_4} ) = 121.388 \ mol \ CH_4[/tex]

Step 4: Check

Follow sig fig rules and round. We are given 3 sig figs.

121.388 mol CH₄ ≈ 121 mol CH₄

Answer:

they are either donated to or taken by another atom to achieve octet arrangement

Explanation:

for example Na+ and Cl- .. they both have one extra and one less electron .

so they donate and receive one electron to/from each other to achieve the octet arrangement ..

Answer:D

Explanation:trust me bro

Answer:

D

Explanation: I took the test

Answer:d

Explanation:

Anser:

Explanation:

hope this helps

Water boils when the vapour pressure is least the atmospheric pressure.

The atmospheric pressure is equal at the top of the mountain.

The air around you has weight, and it presses against everything it touches. That pressure is called atmospheric pressure, or air pressure. It is the force exerted on a surface by the air above it as gravity pulls it to Earth.

As we go up in altitude the air pressure becomes less. When the pressure decreases, it takes less energy to get the water molecules to escape the surface. So the temperature is less than it would be at sea level.

Air pressure is higher or greater at the bottom of a mountain. This is because the height of the air above that level is thicker than at the top.

Pressure is given by the equation, P=rho*g*h, where rho is the air density, g is the gravity value and h is the thickness of the air layer on top of the level where we are considering the pressure.

Therefore, as we can see, at the bottom of the mountain, the thickness h of air is greater, and so is the pressure.

Hence, water boils when the vapour pressure is least the atmospheric pressure and the atmospheric pressure is equal at the top of the mountain.

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The question is incomplete, the complete question is;

In this stoichiometry problem, determine the percentage yield:

Excess aluminum metal reacts with aqueous nickel(II) sulfate to produce aqueous aluminum sulfate and nickel as a precipitate. In this reaction 108 g of aluminum were combined with 464 g of nickel(II) sulfate to produce 274 g of aluminum sulfate.

Answer:

80%

Explanation:

The correct equation for this reaction is;

2Al(s) + 3NiSO4(aq) --------> Al2(SO4)3 + 3Ni(s)

We already know that Al is in excess then NiSO4 is the limiting reactant.

Hence, Number of moles in 464 g of NiSO4 = mass/ molar mass

Molar mass of NiSO4 = 155 g/mol

Number of moles = 464g/155g/mol = 2.99 moles

Number of moles of Al2(SO4)3 = mass/molar mass

molar mass = 342 g/mol

So, Number of moles = 274g/342g/mol = 0.8 moles

Given the stoichiometric reaction equation;

3 moles of NiSO4 yields 1 mole of Al2(SO4)3

2.99 moles of NiSO4 yields 2.99 * 1/3 = 1 mole of Al2(SO4)3

percentage yield is given by; actual yield/ theoretical yield * 100/1

actual yield =  0.8 moles of Al2(SO4)3

Theoretical yield = 1 mole of Al2(SO4)3

Hence;

% yield = 0.8/1 * 100 = 80%

Answer and Explanation:

HCl, also known as hydrochloric acid, has a covalent bond. The hydrogen (H) atom shares an electron with the chlorine (Cl) to form the bond.

Answer:

Fe (s) + Cu^2+ (aq) + SO4^2- (aq) --> Cu (s) + Fe^2+ (aq) + SO4^2- (aq)

Explanation:

The proton is a postitive charge, therefore, being 1 (proton) matched to positive. Whilst neutron (2) is matched to neutral. Thus electron (3) is matched to negative.

Answer:

Chemical Family means a group of elements in the Periodic Table or, more commonly, compounds that share certain physical and chemical characteristics and have a common name.

A period in the periodic table is a row of chemical elements.

metalloid is an element (e.g. arsenic, antimony, or tin) whose properties are intermediate between those of metals and solid nonmetals or semiconductors.

Answer:

cold butter melted when heated, lighting a match, baking cookies,

Explanation:

Answer:

(a) Decomposition: A substance breaks down to smaller species. [e.g. CaCO3(s) → CaO(s) + CO2(g) Decomposition of limestone to calcium oxide (quicklime) and carbon dioxide on heating.]

Answer:

k. e. = 1/2 mv^2

100 = 1/2 * m * 5^2

100 = 1/2 * m * 25

m = 100 *2/25

m = 8 kg

hope it helps you