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3 years ago

Why didn't mendeleev use atomic number to arrange the elements?

1 answer:

8 0

The primary reason for this was that Mendeleev didn't know that atomic numbers actually existed. Atomic numbers were only discovered a period after Mendeleev's time. The use of X-rays made it possible to find the atomic number, and those had not been discovered yet. 
The periodic table was then arranged in 1913 by Henry Moseley in an arrangement according to atomic number.

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Rahul and Sonia were playing with blocks and each of them made a train out of them. Both of them thought of measuring the length

dalvyx [7]

Answer:

See explanation

Explanation:

(a) The handspan is the distance between the tip of the thumb and tip of the little finger when the hand is fully stretched.

b) It is impossible for them to obtain an accurate result by the use of a handspan because it doesn't use any standard unit for measurement. It is entirely subjective and highly prone to human errors.

c) Anupam is quite intelligent and active

3 0

3 years ago

400. mg of an unknown protein are dissolved in enough solvent to make 5.00 mL of solution. The osmotic pressure of this solution

ch4aika [34]

Answer: The molecular weight of protein is $1.14\times 10^2g/mol$

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=iMRT$

or,

$\pi=i\times \frac{m_{solute}\times 1000}{M_{solute}\times V_{solution}\text{ (in mL)}}}\times RT$

where,

$\pi$ = Osmotic pressure of the solution = 0.0861 atm

i = Van't hoff factor = 1 (for non-electrolytes)

$m_{solute}$ = mass of protein = 400 mg = 0.4 g (Conversion factor: 1 g = 1000 mg)

$M_{solute}$ = molar mass of protein = ?

$V_{solution}$ = Volume of solution = 5.00 mL

R = Gas constant = $0.0821\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the solution = $25^oC=[25+273]K=298K$

Putting values in above equation, we get:

$0.0861atm=1\times \frac{0.4g\times 1000}{M\times 100}\times 0.0821\text{ L. atm }mol^{-1}K^{-1}\times 298K\\\\M=1136.62g/mol=1.14\times 10^2g/mol$

Hence, the molecular weight of protein is $1.14\times 10^2g/mol$

4 0

3 years ago

Give the formula of each coordination compound. Include square brackets around the coordination complex. Do not include the oxid

rodikova [14]

Answer:

sodium hexachloroplatinate(IV)- Na2[PtCl6]

dibromobis(ethylenediamine)cobalt(III) bromide- [Co(en)2Br2]Br

pentaamminechlorochromium(III) chloride-[Cr(NH3)5Cl]Cl2

Explanation:

The formulas of the various coordination compounds can be written from their names taking cognisance of the metal oxidation state as shown above. The oxidation state of the metal will determine the number of counter ions present in the coordination compound.

The number ligands are shown by subscripts attached to the ligand symbols. Remember that bidentate ligands such as ethylenediamine bonds to the central metal ion via two donors.

4 0

3 years ago

Water is unique because the density of it's solid is less than the density of it's liquid. Describe how life would be different

Andreas93 [3]

Ice caps would float therefore providing insulation for aquatic life and ensuring they do not freeze due to the cool temperature.

6 0

3 years ago

Which color of sunlight has the greatest amplitude

Zarrin [17]

If you're asking about the greatest amplitude of visible sunlight, then red light waves.
However if you're talking about the colors just in general, then radio waves.

7 0

3 years ago