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Vadim26 [7]
3 years ago
15

If the half-life of hydrogen-3 is 11.8 years, after two half-lives the radioactivity of a sample will be reduced to one-half of

the original amount. If the half-life of hydrogen-3 is 11.8 years, after two half-lives the radioactivity of a sample will be reduced to one-half of the original amount. True False
Chemistry
1 answer:
maw [93]3 years ago
4 0

Answer:

False

Explanation:

Half life is the time period at which the concentration of the radioactive substance in decay reduced to half.

<u>Thus, if the hydrogen-3 has gone 2 half lives, it means that it has first reduced to its half and then again the half of what it was, i.e. 1/4</u>

Thus, after two successive half-lives, the concentration must be 1/4 of the initial concentration and hence, the statement is false.

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Mercury(II) oxide (HgO) decomposes to form mercury (Hg) and oxygen (O2). The balanced chemical equation is shown below.
zavuch27 [327]

15.63 mol. You need 15.63 mol HgO to produce 250.0 g O_2.

<em>Step 1</em>. Convert <em>grams of O_2 to moles of O_2</em>

Moles of O_2 = 250.0 g O_2 × (1 mol O_2/32.00 g O_2) = 7.8125 mol O_2

<em>Step 2</em>. Use the molar ratio of HgO:O_2 to convert <em>moles of O_2 to moles of HgO </em>

Moles of HgO = 0.8885 mol O_2 × (2 mol HgO/1 mol O_2) = <em>15.63 mol HgO</em>

7 0
3 years ago
Read 2 more answers
Which of the following is a radioisotope used to date rock formations older than 50,000 years old?
Natasha2012 [34]
I'm not so sure but I would say Answer Choice B
3 0
2 years ago
Read 2 more answers
QUESTION 11
Iteru [2.4K]
I actually don’t know but good question
6 0
3 years ago
Photosynthesis was another biological phenomenon that occupied the attention of the chemists of the late 18th century. The demon
balu736 [363]

Answer:

In the 1770s, the English clergyman Joseph Priestley (who is credited with the discovery of O2) established the production of oxygen by vegetables recognizing that the process was, apparently, the inverse of animal respiration, which consumed such chemical element.

Explanation:

In 1772, Joseph Priestley in his Recherches sur diversces especes d'air differentiated the air of animal respiration from that emitted by vegetables in the presence of light. Of the latter, which he called "dephlogistic air", he highlighted his purifying property of the environment indicating that: plants far from affecting the air in the same way as animal respiration, produce the opposite effects, and tend to preserve the sweet and healthy atmosphere , when it becomes harmful as a result of the life and breathing of the animals or their death and their rot.

In 1780, Jean Ingeshousz in his Experiences sur les vegetaux completed and reaffirmed the observations of Joseph Priestley. At the same time, he could deny Charles Bonnet's hypothesis, by demonstrating that the air expelled from the leaves comes from inside, and that the stimulating factor of the gaseous emission was not the heat produced by the sun, but the intensity of the light .

It was, finally, Jean Senebier that between 1782 and 1784, found that the "fixed air" dissolved in the water favors the vegetation. From these observations, he hypothesized that "fixed air" (carbon dioxide) is absorbed by the plants, which take it from the atmosphere with the humidity it has and in which it is mixed. Once this gas has been captured, both from the atmosphere and from the ground, it is decomposed in the presence of light by the leaves, releasing the "vital air" (oxygen) and leaving the carbon in the plant.

Thus, at the end of the century the participation of the atmosphere in plant dynamics was already seated, although the how and why of this participation were still unknown and no theory had been formulated to explain the nutritional process as a whole.

3 0
3 years ago
Write a balanced equation formed when the following elements react with oxygen:a)Zinc
Ainat [17]

Explanation:

a) when zinc burnt in oxygen.

2Zn + O2 -----∆-----> 2ZnO(black residue)

b) when carbon burnt in oxygen.

C+O2----∆---> CO2.

c) when sulphur burnt in oxygen.

S+O2-----∆-----> SO2.

d) when Calcium burnt in oxygen.

2Ca+O2-----∆-----> 2CaO(black residue)

e) when Magnesium burnt in oxygen.

2Mg+O2-----∆----> 2MgO.

f) when sodium burnt in oxygen.

4Na+O2----∆-----> 2Na2O.

hope all these reactions help you.

4 0
3 years ago
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