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3 years ago

True or False: The halogens are nonmetals with a -1 charge. True False

Chemistry

1 answer:

Luden [163]3 years ago

3 0

Answer:

they are non metals and all hollagens gain one single electron to fill their valence energy level and all of them form an anion with one single negative charge. so i believe the answer is true

Explanation:

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Please fill this formula

Maurinko [17]

1.) Na
2.) Cl ( at the second blank)
sodium metal+hydrochloric acid

3 0

3 years ago

Uranium-238 decays to lead-206 with a half-life of 4.5 x 109 yr. Determine how much uranium-238 decays in milligrams (to three s

Mamont248 [21]

Answer:

2.15 mg of uranium-238 decays

Explanation:

For decay of radioactive nuclide-

$N=N_{0}.(\frac{1}{2})^{\frac{t}{t_{\frac{1}{2}}}}$

where N is amount of radioactive nuclide after t time, $N_{0}$ is initial amount of radioactive nuclide and $t_{\frac{1}{2}}$ is half life of radioactive nuclide

Here $N_{0}=4.60 mg$ , $t=4.1\times 10^{9}yr$ and $t_{\frac{1}{2}}=4.5\times 10^{9}yr$

So, $N=(4.60mg)\times (\frac{1}{2})^{\frac{4.1\times 10^{9}}{4.5\times 10^{9}}}$

so, N = 2.446 mg

mass of uranium-238 decays = (4.60-2.446) mg = 2.15 mg

3 0

3 years ago

Classify each item by matching as organic

Aloiza [94]

<span>Table salt is inorganic TNT is organic Glucose is organic 2,4-D is organic Limestone is inorganic Water is inorganic What makes a compound organic is the presence of a carbon, with the exception of cabonates. In this case all of the compounds in this list that have carbon except for CaCO3, are organic and the other compounds are inorganic.</span>

3 0

4 years ago

You are given a 1.55 g mixture of calcium nitrate and calcium chloride. You dissolve this mixture in 20 mL of water and add an e

irina [24]

Answer:

13.4 (w/w)% of CaCl₂ in the mixture

Explanation:

All the Cl⁻ that comes from CaCl₂ (Calcium chloride) will be precipitate in presence of AgNO₃ as AgCl.

To solve this problem we must find the moles of AgCl = Moles of Cl⁻. As 2 moles of Cl⁻ are in 1 mole of CaCl₂ we can find the moles of CaCl₂ and its mass in order to find mass percent of calcium chloride in the original mixture.

<em>Moles AgCl - Molar mass: 143.32g/mol -:</em>

0.535g * (1mol / 143.32g) = 3.733x10⁻³ moles AgCl = Moles Cl⁻

<em>Moles CaCl₂:</em>

3.733x10⁻³ moles Cl⁻ * (1mol CaCl₂ / 2mol Cl⁻) = 1.866x10⁻³ moles CaCl₂

<em>Mass CaCl₂ -Molar mass: 110.98g/mol-:</em>

1.866x10⁻³ moles CaCl₂ * (110.98g/mol) = 0.207g of CaCl₂ in the mixture

That means mass percent of CaCl₂ is:

0.207g CaCl₂ / 1.55g * 100 =

<h3>13.4 (w/w)% of CaCl₂ in the mixture</h3>

8 0

3 years ago

Lanthanum-138 has a half-life of 105 billion years. after 525 billion years, how much of a 240 g sample of this radioisotope wil

Reika [66]

The amount of the 240 g sample of the radioisotope that will remain after 525 billion years is 7.5 g

<h3>How to the number of half-lives that has elapsed</h3>

Half-life (t½) = 105 billion years
Time (t) = 525 billion years
Number of half-lives (n) = ?

n = t / t½

n = 525 / 105

n = 5

<h3>How to determine the amount remaining</h3>

Original amount (N₀) = 240 g
Number of half-lives (n) = 5
Amount remaining (N) = ?

N = N₀ / 2ⁿ

N = 240 / 2⁵

N = 240 / 32

N = 7.5 g

Learn more about half life:

brainly.com/question/26374513

#SPJ4

5 0

2 years ago