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erma4kov [3.2K]
3 years ago
7

Problem:

Chemistry
1 answer:
adelina 88 [10]3 years ago
7 0

Answer:

it is Calcium (Ca)

4th period, 2nd group, 2 valence electrons

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A compound decomposes by a first-order process. if 25.0% of the compound decomposes in 60.0 minutes, the half-life of the compou
Tom [10]
Answer:<span>d. 145 minutes
</span>
Half-life is the time needed for a radioactive to decay half of its weight. The formula to find the half-life would be:

Nt= N0 (1/2)^ t/h

Nt= the final mass
N0= the initial mass
t= time passed
h= half-life

If 25.0% of the compound decomposes that means the final mass would be 75% of initial mass. Then the half-live for the compound would be:
Nt= N0 (1/2)^ t/h
75%= 100% * (1/2)^ (60min/h)
3/4= 1/2^(60min/h)
log2 3/4 = log2 1/2^(60min/h)
0.41503749928 = -60min/h
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3 0
3 years ago
Determine and compare the physical properties of potassium chloride and zinc and wax​. please
gayaneshka [121]

Answer:

odorless, crystalline, white solid with a sour taste.

Explanation:

4 0
2 years ago
The charge on a magnesium ion is +2. When it formed an ionic compound with another element, it lost 2... what?
Naya [18.7K]

Answer:  electrons

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6 0
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What are the limitations of litmus paper and Phenolphthalein indicators? Name to other indicators that can be used that do not h
jenyasd209 [6]

Answer:

Here's what I find.

Explanation:

An indicator is usually is a weak acid in which the acid and base forms have different colours. Most indicators change colour over a narrow pH range.

(a) Litmus

Litmus is red in acid (< pH 5) and blue in base (> pH 8).

This is a rather wide pH range, so litmus is not much good in titrations.

However, the range is which it changes colour includes pH 7 (neutral), so it is good for distinguishing between acids and bases.

(b) Phenolphthalein

Phenolphthalein  is colourless in acid (< pH 8.3) and red in base (> pH 10).

This is a narrow pH range, so phenolphthalein is good for titrating acids with strong bases..

However, it can't distinguish between acids and weakly basic solutions.

It would be colourless in a strongly acid solution with pH =1 and in a basic solution with pH = 8.

(c) Other indicators  

Other acid-base indicators have the general limitations as phenolphthalein. Most of them have a small pH range, so they are useful in acid-base titrations.

The only one that could serve as a general acid-base indicator is bromothymol blue, which has a pH range of 6.0 to 7.6.

5 0
3 years ago
The molecule I2 has a lower melting point than Cl2.<br><br> TRUE<br><br> FALSE
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True. <span><span>Melting points decrease down a group and increase across a period.</span> </span>
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3 years ago
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