The radioisotope radon-222 has half-life of 3.8 days. how much of a 73.9-g sample of radon-222 would be left after approximately 23 days?

Answers

Answer 1

Answer: This can be solved by the equation:

A = Aoe^(-ln2/t)T
where Ao is the initial amount of the substance ( 73.9-g sample of radon-222 ), t is the half-life time (3.8 days) and T is the time elapsed. Plugging in the values in the equation, the substance left is 1.11g.

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Hydrogen peroxide can be prepared by the reaction of barium peroxide with sulfuric acid according to

Answers

Answer:

31.43 ml of sulfuric acid is needed to react with 23.1 g of barium peroxide.

Explanation:

For the reaction:

BaO₂(s) + H₂SO₄(aq) ⇒ BaSO₄(s) + H₂O₂(aq)

We need 1 mole of BaO₂ to react with 1 mole of H₂SO₄ and then forming 1 mole of BaSO₄ and 1 mole of H₂O₂.

We know that 4.5 M solution of H₂SO₄ means 4.5 moles of H₂SO₄ in 1000 ml of solution.

Then,

23.1 g BaO₂ × $(1 mole_(BaO_2))/(163.33g_(BaO_2))$ × $\frac{1 mole_{H_(2)SO_(4)}}{1mole_(BaO_2)}$ × $\frac{1000ml}{4.5 mole_{H_(2)SO_(4)}}$ = 31.43 ml H₂SO₄

BaO₂ + H₂SO₄ ⇒ BaSO₄ + H₂O₂
169g : 98g
23.1g : mx

mx = [23.1*98g]/169g ≈ 13.4g
Mr = 98g/mol

n = 13.4g/98g/mol ≈ 0.14mol

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Which foods contain acids? Check all that apply:a.) limes b.) sourdough bread c.) water d.) sugar e.) honey f.) milk g.) lemons h.) tomatoes

Answers

Answer:

Limes

Lemons

Tomatoes

Explanation:

They all contain citric acid - the others are basic

Answer:

a.) Limes

b.) Sourdough bread

g.) Lemons

h.) Tomatos

Explanation:

Elements can combine to form molecules, like o2 or co2. elements combine to form molecules and these elements are joined together by a. chemical bonds.
b. nuclear energy.
c. sharing nuclei.
d. attractive forces.

Answers

Elements can combine to form molecules, like o2 or co2. elements combine to form molecules and these elements are joined together by chemical bonds i.e covalent bond in this molecule so option A is correct
hope this helps

Answer:

a. Chemical bonds.

Explanation:

Hello,

In this case, it is necessary to know that when two elements are not stable by their own they should bond with an other atom of the same element via chemical bonds whereby the valence electrons act as bridges connecting the atoms. Some examples are diatomic-gaseous hydrogen, oxygen, nitrogen, chlorine, iodine, fluorine and bromine. Moreover, such chemical bonding is represented by lines binding the elements as shown on the attached picture.

Best regards.

Which statement explains how the bands in the crystal of a metal are like atomic orbitals?

Answers

Please provide the choices here.

The similarity of the bands in the crystal of a metal to the atomic orbitals can be explained by the band theory of metals. In an atom, when the electrons get excited, the electrons jumps to a higher orbital so as to reach equilibrium. This is analogous to the electrons in the metals which also jumps to another band once excited by an external energy (e.g. electrical energy).

Answer:

Explanation:

They both allow electrons to move from lower energy levels to higher energy levels.

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b. surface area
c. concentration
d. heat

Answers

I would go with B as more of the reactant is exposed per mol. A catalyst provides and alternate reaction path that reduces the activation energy but not necessarily exposes more of the reactant. Increasing the concentration wont increase the amount of exposed area nor will increasing the tempurature.

Diets that are high in ____ are associated with an increased incidence of hypertension.calcium
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sodium
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Answers

sodium but i think sugar would be a good answer

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