80. When water forms ice, hydrogen bonds around a water molecules are at ... apart.

He predicted an element with an atomic weight between 65 (zinc) and 75 (arsenic) with a valence similar to aluminum that he name

skad [1K]

Answer:

Scandium

Explanation:

Mendeleev played an important role in the development of the modern periodic table. His periodic table was filled with gaps. He said that these gaps were elements that were yet to be discovered. He rightly predicted many elements which have now been discovered and fitted in their proper places in the periodic table.

He used the prefix ''eka'' to refer to elements whose properties were alike but were yet to be discovered at that time.

The compound named ekaboron which he predicted to have an atomic weight between 65 (zinc) and 75 (arsenic) with a valence similar to aluminum was later discovered in 1879 and properly named scandium.

3 0

3 years ago

You can obtain a rough estimate of the size of a molecule with the following simple experiment: Let a droplet of oil spread out

mina [271]

Answer:

The diameter of the oil molecule is $4.4674\times 10^{-8} cm$ .

Explanation:

Mass of the oil drop = $m=9.00\times 10^{-7} kg$

Density of the oil drop = $d=918 kg/m^3$

Volume of the oil drop: v

$d=\frac{m}{v}$

$v=\frac{m}{d}=\frac{9.00\times 10^{-7} kg}{918 kg/m^3}$

Thickness of the oil drop is 1 molecule thick.So, let the thickness of the drop or diameter of the molecule be x.

Radius of the oil drop on the water surface,r = 41.8 cm = 0.418 m

1 cm = 0.01 m

Surface of the sphere is given as: a = $4\pi r^2$

$a=4\times 3.14\times (0.418 m)^2=2.1945 m^2$

Volume of the oil drop = v = Area × thickness

$\frac{9.00\times 10^{-7} kg}{918 kg/m^3}=2.1945 m^2\times x$

$x= 4.4674\times 10^{-10} m= 4.4674\times 10^{-8} cm$

The thickness of the oil drop is $4.4674\times 10^{-8} cm$ and so is the diameter of the molecule.

6 0

3 years ago

Balance this equation. If a coefficient of "1" is required, choose "blank" for that box. ____CO +____ O2 → ____CO2

Black_prince [1.1K]

<h3><u>Answer;</u></h3>

2, Blank, 2 ;

<h3><u>Explanation;</u></h3>

The balanced chemical equation would be;

2 CO + O2 → 2 CO2

Balancing a chemical equation ensures that the number of atoms of each element are equal on both the reactants side and the products side. This ensures that the law of conservation of mass is obeyed in chemical reactions.

4 0

3 years ago

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What two dose the transfer of light energy require

IrinaK [193]

Answer:

Magnetic fields and Electric fields

Explanation:

3 0

3 years ago

PLS help

viktelen [127]

Answer:

d . Sc2O5

Explanation:

Hello,

In this case, when forming oxides from a metal and oxygen, for us to find out each element's subscript, we must exchange them as shown below, considering +5 for scandium:

$Sc^{+5}_2O^{-2}_5$

For that reason, the answer is d . Sc2O5

Best regards.

3 0

3 years ago

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