PLS HELP i will give 10 points
In Mendeleev’s Periodic Table, why was there no mention of Noble gases like Helium, Neon and Argon?

Answers

Answer 1

Answer:Answer choices are:

A. These elements did not fit in with his pattern.

B. These elements are gases and he didn't include gases.

C. The atoms of these elements had no atomic mass.

D. These elements had not yet been discovered.

___________________________________________________________

Correct answer choice is:

D. These elements had not yet been discovered.


Related Questions

which statements correctly identify charecteristics of earth and jupiter

Answers

Answer:

There are no statements listed but.... a few ideas

Explanation:

Earth is very small in comparison to Jupiter which is the largest planet of the solar system.

The diameter of Jupiter is 11 times greater than the diameter of the earth.

Earth is a terrestrial planet, whereas Jupiter is a Jovian planet.

On the periodic table, all of the cards in each row (across) have the same what?

Answers

Elements in the same period or group have the same physical properties

What is the purpose of continuing to heat a substance after it reaches a temperature plateau?

Answers

They are changes in bonding energy between the molecules. ... Immediately after the molecular bonds in the ice are broken the molecules are moving (vibrating) at the same average speed as before, so their average kinetic energy remains the same, and, thus, their Kelvin temperature remains the same."

Identify what type of reaction is this
2AgCl + H2 → 2Ag + 2HCI

Answers

Answer:

single displacement

Explanation:

Which element or compound has lost electrons in this oxidation-reduction reaction?

4Li + 2CoO → 2Co + 2Li2O

A.
CoO
B.
Li2O
C.
Li
D.
Co
E.
O

Answers

C: Lithium. Before it was 4Li and after the oxidation it turned out to 2Li

Answer:

C. Li

Explanation:

9. Do all enzymes function at the same pH?

Answers

Each enzyme has an optimum pH but it also has a working range of pH values at which it will still work well. This depends on the type of enzyme. The enzyme pepsin breaks down proteins in the acidic conditions of the stomach. ... Catalase has an optimum pH of 9 and a working range of between pH 7-11.        Hope this was helpful

Explanation:

How does plate movement affect earths crust?

Answers

the answer is yes it does affect hope this helps did this before!

Which of the following statements is true a A) dams are made of molecules B) Adams can join to form molecules C) atoms contain more than one element D) some atoms do not have protons

Answers

Statement B is true because atoms are single particles that come together to form compounds and molecules.

Where does the light we see from the moon come from?

Answers

The reflection if the sun

Is warm water or cold water more dense

Answers

Cold water is denser
ANSWER
Cold water has a higher density then warm water

Hope this helps :)

Write the combustion equation for propane (C3H8). What is the sum of the coefficients for the reactants and products? Group of answer choices 13 14 10 11 12

Answers

Answer:

13

Explanation:

Let's consider the unbalanced equation for the combustion of propane.

C₃H₈ + O₂ ⇒ CO₂ + H₂O

We will begin balancing H atoms by multiplying H₂O by 4.

C₃H₈ + O₂ ⇒ CO₂ + 4 H₂O

Now, we balance C atoms by multiplying CO₂ by 3.

C₃H₈ + O₂ ⇒ 3 CO₂ + 4 H₂O

Finally, we get the balanced equation multiplying O₂ by 5.

C₃H₈ + 5 O₂ ⇒ 3 CO₂ + 4 H₂O

The sum of the coefficients is 1 + 5 + 3 + 4 = 13.

Please help ASAP!!

I am not sure how to solve this!

Answers

Answer:

Potassium (K) has 19 protons.

Each neutral atom of Potassium has 19 electrons.

Explanation:

A) Potassium has 19 protons because the atomic number tells us how many protons are in an atom of the element. (The atomic number is the number above the element symbol. For example, the number above "K" is 19, which is the atomic number).

B) If an atom is neutral, this means that the atom has neutral energy. Protons give positive energy and electrons give negative energy. For the atom to be neutral, the atom must have balanced energy, therefore, making the number of electrons equal to the number of protons in a neutral atom.

how does the law of conservation of mass applies to all chemical reactions?

Answers

Answer:

the mass of any one element at the beginning of a reaction will equal the mass of that element at the end of the reaction. If we account for all reactants and products in a chemical reaction, the total mass will be the same at any point in time in any closed system.

Explanation:

The law of conservation is Matter cannot be created or destroyed in chemical reactions so it means exactly that

How many molecules are in 83.2 g of chlorine gas (Cl2)?

Group of answer choices
1.42 x 10^24 molecules
1.78 x 10^28 molecules
7.04 x 10^23 molecules
14.2 x 10^24 molecules

Answers

Answer:

Try everything or guess, that will always work

1.42 x 10^24 molecules

1.78 x 10^28 molecules

7.04 x 10^23 molecules

14.2 x 10^24 molecules

Explanation:

Which statement best distinguishes comets from nebulae? A. Nebulae can form stars, but comets cannot. B. Comets are in galaxies, but nebulae are not. C. Nebulae have moons. but comets do not. D. Comets can be part of a constellation, but nebulae cannot.

Answers

Answer: A-Nebulae can form stars, comets cannot

Explanation: Simply comets get destroyed and Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. In these regions, the formations of gas, dust, and other materials "clump" together to form denser regions, which attract further matter, and eventually will become dense enough to form stars.

While Nebulae is a body of interstellar cloud, made of cosmic dust, hydrogen etc , Comets are balls of rocks, frozen gases, that revolve the Sun.

Nebulae can form stars, but comets cannot. Option A is correct

What distinguishes comets from nebulae?

Nebulae is a different body of interstellar cloud, they are made out of cosmic dust, hydrogen, helium, and molecular clouds.

While Comets are balls of rock, frozen gases, and other particles that revolve around the Sun.

Read more about Galaxy

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Which of the following is/are true regarding chemical
nomenclature?

A. All elements in a compound must be included
in the name.
B. Ionic and molecular nomenclature have
different rules.
C. A formula for an ionic compound is written
with the cation first followed by the anion.
D. A chemical formula must always be reduced to
the lowest whole number ratio.

Answers

Answer:

c

Explanation:

i took the quiz

An initial mixture of nitrogen gas and hydrogen gas is reacted in a rigid container at a certain temperature as follows:

Answers

Answer:

The concentration of nitrogen gas and hydrogen gas that reacted initially are 10.0 M and 11.0 M respectively.

Note: The question is incomplete. The complete question is as follows:

An initial mixture of nitrogen gas and hydrogen gas is reacted in a rigid container at a certain temperature as follows:

3H2(g)+N2(g)⇌2NH3(g)

At equilibrium, the concentrations are

[H2] = 5.0 M, [N2] = 8.0 M, and [NH3] = 4.0 M.

What were the concentrations of nitrogen gas and hydrogen gas that were reacted initially?

Explanation:

Given the following data:

Concentration of H2 at equilibrium = 5.0 M

Concentration of N2 at equilibrium = 8.0 M

Concentration of NH3 at equilibrium = 4.0 M

The given equilibrium reaction is,

Initial                    a             b            c

Change                -3x          -x         +2x

Equilibrium         (a-3x)       (b-x)     +2x

The value of x is calculated from the equilibrium of NH3

Concentration of NH3 at equilibrium = 4.0 M  = 2x

x = 2.0 M

Substituting the value of x above

Initial Concentration of H2:

a - 3 × 2.0 M = 5.0 M

a = 6.0 M + 5 = 11.0 M

Initial Concentration of N2:

b - 2.0 M = 8 M

b = 8.0 M + 2.0 M

b = 10.0 M

Therefore, the concentration of nitrogen gas and hydrogen gas that reacted initially are 10.0 M and 11.0 M respectively.

Why has popular media had a negative impact on forensic science?

Answers

Answer:

Because it serves their agenda.

1) El CO2 que los astronautas exhalan se extrae de la atmósfera de la nave espacial por reacción con KOH según la reacción: CO2 (g) + 2 KOH (l) → K2CO3 (s) + H2O (l) a) Cúantos gramos de CO2 se pueden extraer con 500 g de KOH ? b) Cuántos gramos de agua se producen? 2) Cuando se hacen reaccionar hidrógeno y nitrógeno se produce amoniaco, un fertilizante benéfico para las plantas. ¿Cuántos moles de hidrógeno se requieren para que reaccionen con 12.75 moles de nitrógeno? La reacción es la siguiente: N2 + 3 H2 → 2NH3 3) El propano (C3H8) es usado como combustible en los hogares, reacciona con el oxigeno para producir dióxido de carbono (CO2) y agua (H2O) mediante la siguiente reacción: C3H8 + 5 O2 → 3 CO2 + 4 H2O a) Si se queman 2 Litros de propano (C3H8) calcula los litros de CO2 que se emiten a la atmósfera.

Answers

Answer:

a. 4.46 moles de CO₂

b. 80.2 g de H₂O

38.25 moles de H₂

5.55 L de dióxido de carbono

Explanation:

Comenzamos con la reacción: CO₂ (g) + 2 KOH (l) → K₂CO₃ ↓ (s) + H₂O (l)

a. Podemos ver que la relación estequiométrica es 2 a 1.

Pasamos la masa de KOH a moles → 500 g . 1mol/ 56.1g = 8.91 moles

2 moles de KOH necesitan 1 mol de dióxido

Entonces, 8.91 moles necesitarán (8.91 . 1)/2 = 4.46 moles

Convertimos los moles en masa → 4.46 mol . 44g /1mol = 196 g de CO₂

b. Como no tenemos información de los reactivos, trabajamos con el KOH (recorda que siempre hacemos los cálculos con el reactivo limitante).

La relacion estequiometrica también es 2 a 1.

Con 2 moles de KOH producimos 1 mol de agua

Entonces 8.91 moles producirán la mitad, 4.46 moles

Pasamos a gramos  → 4.46 mol . 18g /1mol = 80.2 g de H₂O

N₂ + 3H₂ → 2NH₃

En esta relacion, la relación de moles es 1 a 3.

1 mol de N₂ necesita 3 moles de H₂ para llevar a cabo la reacción

12.75 moles de nitrogeno reaccionarán con (12.75 . 3)/ 1 = 38.25 moles de H₂

La siguiente es una reacción de combustión:

C₃H₈ + 5O₂ → 3 CO₂ + 4 H₂O

Como en este caso tenemos volumen, necesitamos averiguar la densidad del propano para sacar la masa y de ahi los moles:

Densidad del propano es 1.83 g/L

Si tenemos 2 Litros de gas, entonces tendremos el doble de masa

2L .  1.83 g/L = 3.66 g

Convertimos a moles → 3.66 g . 1 mol/44g = 0.083 moles

1 mol de propano produce 3 moles de dióxido.

0.083 moles producirán (0.083 .3) /1 = 0.249 moles

Convertimos a gramos → 0.249 moles . 44g/ 1mol = 10.98 g

La densidad del CO₂ es 1.976 g/L

d = m/V → V = m/d →  10.98 g / 1.976 L = 5.55 L

In which location would fishermen most likely catch a greater number of fish?
O A. at the shoreline
B. in an upwelling
C. in the intertidal zone
D. on the deep-ocean floor

Answers

A am pretty sure because I go fishing and yea

Which is a characteristic of atoms?
They come in ten major
They are the smallest units of matter
They can be divided
They cannot combine together

Answers

Answer:

the second one ..........

what are the reactions in a chemical reaction

A. the new substances that are produced
B. the substances that interact
C. the catalysts
D. the chemical formula of the substances ​

Answers

Answer:

B

Explanation:

chemical reaction a process in which one or more substance the recessed ants are converted to one or more different substances the products substances are either chemical elements or compounds a chemical reaction rearranges the consulstituent atoms of reactants to create different substances products

1. 2 NH3 → N2 + 3 H2
If 2.8248 moles of H2 are produced, how many moles of NH3 were reacted?
2. CaCO3 → CaO + CO2
If 288.53 grams of CaCO3 are reacted, how many moles of CaO will be produced?
3. 2 KClO3 → 2 KCl + 3 O2
If 92.25 grams of KCl are produced, how many grams of O2 will also be produced?
4. 2 As + 6 NaOH → 2 Na3AsO3 + 3 H2
If 3.0482 moles of NaOH are reacted with 212.2 grams of As, how many moles of H2 will be produced?
5. Sn + 2 CuCl → SnCl2 + 2 Cu
If 2.1492 moles of CuCl are reacted with 355.58 grams of Sn, how many moles of SnCl2 will be produced?

Answers

Answer:

BRO IM IN ONLY 7TH GRADE

Explanation:

For each of the following unbalanced equations indicate how many moles of the second reactant would be required to react exalt with 0.275 mole of the first reactant. Balance the equation.Co(s) + P4 (s) Co3P2 (s)

Answers

Answer:

0.183 mol

Explanation:

so balenced equation is 6Co+4P=2(Co3P2)

so so the ratio is 6:4

so .275/6*4

=0.183 mol I think

The Answer will be:  0.183 mol

 so that the balanced equation is 6Co+4P=2(Co3P2) When the ratio is 6:4

       so that .275/6*4

      =0.183 mol.

When According to the A balanced chemical is equation has been equal numbers of atoms that are for each element they are involved in the reaction and its represented on the reactant and its product sides.Also that This is a better requirement that makes the equation must be satisfied and also that to be consistent with the law of conservation of the matter. then It may occur that it is confirmed by simply summing the numbers of atoms and also molecules on it either side of the arrow and it's comparing these sums to ensure that they are equal.  

( 1 CO 2  molecule  ×  2 O atoms CO 2 molecule) + ( 2 H 2 O molecule  × 1 O atom H 2 Molecule  ) = 4 O atoms

Learn more about:

https://brainly.com/question/13719614

what is 5x6?

also, to all of the slime rancher players!!

what is your favorite slime? mine is the dervish. dem lil tornado beans :D ​

Answers

Answer:

30 boiii lol my fav is 110% fire slime or tangle slime. they are BESTTT

2. If the direction of an applied force is changed once, to what was the force applied?

A. a compound machine
B. a heat engine
C. an electrical machine
D. a simple machine

Answers

Answer:

the answer is( D)a simple machine

How many moles are in 187 grams of NH3?
11 moles
13.4
moles
3,179 moles
2,618 moles

Answers

Answer:

3126 moles

Explanation:

put them all together times them and add

Which is Earth's largest source of drinkable water?
O A. lakes
O B. rivers
OC, oceans
O D. aquifers

Answers

depends on what you’re going for. i’d say aquifers. but you can drink from clean rivers

Answer:

D.)

Explanation:

As the slope or incline of the land increases, the speed of the water ________________.

Answers

Answer:

increase

Explanation:

ok so this is a answer

Help only if you know the answer and I will mark brainliest ⚡️⚡️⚡️

Answers

Answer:

450 kilometers

Explanation:

i used a calculator

Answer:

450 km

Explanation:

I) Construct an equation to find the distance:

speed x time = distance

15 x 30 = d

II) Solve:

15 x 30 = 450

450 km

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