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Grace [21]
3 years ago
11

When was the idea of a atom first devloped

Chemistry
1 answer:
bija089 [108]3 years ago
6 0

Answer:

Around 450 B.C.

Explanation:

The idea was forgotten until the 1800 when John Dalton re-introduced the atom.

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A blood specimen is collected in a heparin-containing tube for calcium and magnesium determination. Upon centrifugation, the pla
Firdavs [7]

Answer:

False hypermagnesaemia

Explanation:

Magnesium is predominantly an intracellular divalent action and it is important for optimal cellular function. It is an essential cofactor to many enzymes as well as being important for membrane function.

The body contain about 1 mol (approximately 25g) of magnesium.

Hemolyzed specimen will result in release of magnesium from intracellular to extracellular, causing elevation of the blood level of magnesium. This is a false hypermagnesaemia because it doesn't represent the real blood level.

3 0
3 years ago
Determine the mass of NH4Cl that must be dissolved in 100. grams of H2O to produce a saturated solution at 70.°C.
Delvig [45]
If you look at your Chemistry reference table, the answer should be about 62g of NH4Cl. Lining up the lines of solubility and temperature, you should come to that answer.
3 0
3 years ago
ethanol has a density of 0.789 g/cm3, how many pounds of ethanol would be in a drum containing 7.0 gallons of ethanol
max2010maxim [7]

From the density of ethanol given, the number of pounds of ethanol in the drum will be 46.099 pounds.

<h3>How to calculate density</h3>

Density of ethanol = 0.789/cm³

1 gallon = 3785.4ml

Volume of ethanol = 7 gallons = 7 × 3785.4ml = 26497.8ml

Mass of ethanol = Volume × Density.

= 26497.8 × 0.789

= 20906.764g

Since 1g = 0.002205 pounds, the mass of ethanol will be:

= 20906.764 × 0.002205

= 46.099 pounds.

Learn more about density on:

brainly.com/question/11730603

5 0
2 years ago
Which of the following trends is indirectly proportional to effective nuclear charge, Zeff
Julli [10]

Answer : Option C) Atomic Size

Explanation : The atomic radius of the elements is found to be decreasing if we go from left to right in the modern periodic table. Accordingly, Z_{eff} increases as the number of shielding electrons present in the atomic nucleus of the periodic elements which lies in the same row remains constant while the number of protons in each atomic shell increases.

The effective nuclear charge Z_{eff} of an atom is defined as the net positive charge which is felt by the valence electron of the atomic element.

When Z_{eff} is observed to decrease, it is seen that the atomic radius grows in size. So, it explains the inverse relationship between both. This phenomenon occurs, because there is more screening of the electrons from the nucleus taking place, which is observed due to decrease the attraction between the electron and the nucleus.

7 0
3 years ago
Read 2 more answers
What products result from mixing aqueous solutions of Cr(NO3)2(aq) and NaOH(aq)? Question 10 options: Cr(OH)2(s), Na+(aq), and N
Alecsey [184]

Answer:

Cr(OH)2(s), Na+(aq), and NO3−(aq)

Explanation:

Let is consider the molecular equation;

2NaOH(aq) + Cr(NO3)2(aq) -----> 2NaNO3(aq) + Cr(OH)2(s)

This is a double displacement or double replacement reaction. The reacting species exchange their partners. We can see here that both the sodium ion and chromium II ion both exchanged partners and picked up each others partners in the product.

Sodium ions and nitrate ions now remain in the solution while chromium II hydroxide which is insoluble is precipitated out of the solution as a solid hence the answer.

4 0
4 years ago
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