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Vladimir [108]
3 years ago
9

Which of these elements has four valence electrons

Chemistry
1 answer:
exis [7]3 years ago
7 0
What are the elements?

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The half-life of radium-226 is 1590 years. if a sample contains 100 mg, how many mg will remain after 1000 years?
AlladinOne [14]

Answer:

64.52 mg.

Explanation:

The following data were obtained from the question:

Half life (t½) = 1590 years

Initial amount (N₀) = 100 mg

Time (t) = 1000 years.

Final amount (N) =.?

Next, we shall determine the rate constant (K).

This is illustrated below:

Half life (t½) = 1590 years

Rate/decay constant (K) =?

K = 0.693 / t½

K = 0.693/1590

K = 4.36×10¯⁴ / year.

Finally, we shall determine the amount that will remain after 1000 years as follow:

Half life (t½) = 1590 years

Initial amount (N₀) = 100 mg

Time (t) = 1000 years.

Rate constant = 4.36×10¯⁴ / year.

Final amount (N) =.?

Log (N₀/N) = kt/2.3

Log (100/N) = 4.36×10¯⁴ × 1000/2.3

Log (100/N) = 0.436/2.3

Log (100/N) = 0.1896

Take the antilog

100/N = antilog (0.1896)

100/N = 1.55

Cross multiply

N x 1.55 = 100

Divide both side by 1.55

N = 100/1.55

N = 64.52 mg

Therefore, the amount that remained after 1000 years is 64.52 mg

7 0
3 years ago
Acids are described as corrosive because they a. turn litmus blue. b. taste bitter. c. “eat away” at other materials. d. feel sl
Masteriza [31]

Answer:

C

Explanation:

acids are corrosive since they tend to destroy every single thing they do get a big example is the acidic rain which tends to corrode iron sheet thus making them to appear worn out and full of rust

4 0
3 years ago
Read 2 more answers
___Al+NaOH=>__Na3AlO3+H2
MaRussiya [10]

Explanation:

<em><u>2Al + 2NaOH + 6H2O → 2Na[Al(OH)4] + 3H2</u></em>

<em><u>...</u></em>

8 0
3 years ago
Tough and malleable form of iron is
Alenkasestr [34]
The answer to your question is A. Wrought iron because amongst its other properties, wrought iron becomes soft at red heat, and can be easily be forged and forge welded.
4 0
3 years ago
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In a redux reaction why does an <br> element oxidation number decreases
Olin [163]

Answer:

Decreases

Explanation:

An element's oxidation number decreases because it gained electrons.

7 0
3 years ago
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