CHEMISTRY HIGH SCHOOL

Which of the following elements have the same number of valence electrons?l. nitrogen (N)
ll. oxygen (O)
lll. fluorine (F)
lv. sulfur (S)
v. selenium (Se)

A. IV, and V
B. I, II, and III
C. I, II, and IV
D. II, IV, and V

Answers

Answer 1

Answer:

The answer is II. Oxygen, IV. Sulfur, and V. Selenium.

Explanation:

Going down the list that was provided, we can use the periodic table of elements to determine the valence electrons.

- Nitrogen has 5 valence electrons

- Oxygen has 6 valence electrons

- Fluorine has 7 valence electrons

- Sulfur has 6 valence electrons

- Selenium has 6 valence electrons

Since oxygen, sulfur, and selenium all have 6 valence electrons, then that is the correct answer.

I hope this helps you!

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Which of these statements is NOT TRUE? Scientists propose explanations that can be explained by examining evidence. Scientists propose explanations that can be explained by examining evidence. Science is an organized way to investigate, understand, and explain events in the natural world. Science is an organized way to investigate, understand, and explain events in the natural world. Scientists collect and organize information randomly, looking for patterns and connections between events. Scientists collect and organize information randomly, looking for patterns and connections between events. Science deals only with the natural world.

Answers

Answer:

The correct option is;

Scientist propose explanations that can be explained by examining evidence

Explanation:

A scientists makes an hypotheses based on possible natural processes to explain the origin and/or the nature of the characteristics of a natural observation. The scientist then source more data and information to put their hypotheses to test. Due to the fact that an hypotheses is based on observable processes and/or mechanisms, the given hypotheses can be further tested by other scientists through the use of their individually sourced data. From the result of the assessment, the hypotheses can be either accepted or rejected to enable the better clarification of the hypotheses when accepted or the development of a new hypotheses when rejected.

Methane (CH4, 16.05 g/mol) reacts with oxygen to form carbon dioxide (CO2, 44.01 g/mol) and water (H2O, 18.02 g/mol). Assume that you design a system for converting methane to carbon dioxide and water. To test the efficiency of the system in the laboratory, you burn 5.00 g methane. The actual yield is 6.10 g water. What is your percent yield?

Answers

Answer:

The percent yield of reaction is 54.32%.

Explanation:

$CH_4+3O_2\rightarrow CO_2+2H_2O$

Moles of methane = $(5.00 g)/(16.05 g/mol)=0.3115 mol$

According to reaction, 1 mole of methane gives 2 moles of water .

The 0.3115 moles of methane will give:

$(2)/(1)* 0.3115 mol=0.623 mol$ of water

Mass of 0.9345 moles of water = 0.623 mol × 18.02 g/mol = 11.23 g.

Theoretical yield of methane = 11.23 g.

Experimental yield of methane = 6.10 g.

The percent yield of reaction:

$\%(Yield)=\frac{\text{Experimental yield}}{\text{Theoretical yield}}* 100$

The percent yield of reaction is :

$\%(Yield)=(6.10 g )/(11.23 g)* 100=54.32\%$

Answer:54.5

Explanation:

As an atom becomes an ion, its mass number(1) decreases(2) increases(3) remains the same

Answers

As an atom becomes an ion, its mass number $\boxed{\left( 3 \right){\text{ remains the same}}}$

Further explanation:

The smallest unit of an element is called an atom. It is also known as the building block of matter. An atom is generally represented as $_{\text{Z}}^{\text{A}}{\text{X}}$ , where X is the symbol of the element, A is its atomic mass or mass number and Z is its atomic number.

The number of protons present in the atomic nucleus is termed as the atomic number (Z) whereas the total number of nucleons present in the nucleus of an atom is called mass number or atomic mass (A).

When electrons are either gained or lost from the neutral atom, it results in the formation of ions. Cations are the positively charged ions that are formed due to the removal of electrons from the neutral atom. Anions are the negatively charged ions that result from the addition of electrons to the neutral atom.

Since the formation of either type of ion requires gain or loss of electrons but mass number is the total number of protons and neutrons present in the atomic nucleus, the mass number remains the same when ions are formed from their respective ions. Therefore option (3) is the correct answer.

Consider an example of a sodium atom whose atomic number is 11 so it has an electronic configuration of $1{s^2}2{s^2}2{p^6}3{s^1}$ . It loses one electron to form its monovalent ion, ${\text{N}}{{\text{a}}^ + }$ which has the configuration of $1{s^2}2{s^2}2{p^6}$ . The number of electrons in Na is 11 while that in ${\text{N}}{{\text{a}}^ + }$ is 10. But both the species have same number of protons and neutrons in them. So the mass number remains unchanged if an atom forms its ions.

Learn more:

1. Component of John Dalton’s atomic theory: brainly.com/question/2357175

2. Basis of investigation for the scientists: brainly.com/question/158048

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Atomic structure

Keywords: atom, matter, atomic nucleus, proton, electron, neutron, cations, anions, Na, 11, Na+, electronic configuration.

Becoming an ion involves gaining or losing electrons
Electrons have a relative mass of 0
So adding or removing them doesn't change the mass of the atom
So the answer is (3) remains the same

How many mole are in 2.84*10^22 molecules of h2

Answers

Avogadro's Number and the Mole. The mole is represented by Avogadro's number, which is 6.022×1023 atoms or molecules per mol.

CaCO3---> CaO+CO2 How many moles of CaO form when 98.60g CaCO3 decompose? 98.60g CaCO3= ______ mol CaO

Answers

Answer:

0.9852 moles of CaO

Explanation:

Reaction equation for the decomposition of CaCO₃:

CaCO₃ → CaO + CO₂

The question asks how many moles of CaO form when 98.60g of CaCO₃ decompose.

We can see from the reaction equation that for every mol of CaCO₃, one mol of CaO will be produced (molar ratio 1:1)

_____________________________________________________

So first we need to calculate how many moles are the 98.60g of CaCO₃:

Molar Mass of CaCO₃ = molar mass Ca + molar mass C + 3 * molar mass O

= 40.078 + 12.011 + 3 * 15.999 = 100.086 g/mol

Moles of CaCO₃ = mass CaCO₃ / molar mass CaCO₃

Moles of CaCO₃ = 98.60 g / 100.086 g/mol = 0.9852 moles CaCO₃

________________________________________________________

As we said before for every mol of CaCO₃, one mol of CaO is produced.

So the decomposition of 0.9852 moles of CaCO₃ will produce 0.9852 moles of CaO.

Hey I think it is going to be 0986 moles. Cuz we can see that no. of moles of CaCO3 which will decompose is equivalent to the no. of CaO . Now it's just the matter of finding the no. of moles of CaCO3 .

no.of moles=mass /relative molecular mass

Water molecules attract to one another to form what kind of bonds?