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3 years ago

Who are the scientists that contributed in arranging of the periodic table?

1 answer:

7 0

In 1869 Russian chemist DIMITRI MENDELEEV started the development of the periodic table,arranging chemical elements by atomic mass. He predicted the discovery of other elements and left spaces open in his periodic table for them. HOPE THIS HELPSS HAVE A GREAT DAY <333

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Looking at the structure of caffeine, explain why it is very soluble in a non-polar solvent and a little soluble in water.

olasank [31]

Because in caffeine the don’t use that much soluble in caffeine bis cause then there would be no flavor of caffeine but in water they do so the water doesn’t affect other to stop the solvent from getting stuck.

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3 years ago

How many grams of NH3 are in 45.9

Ostrovityanka [42]

I believe it is 32.3g, I apologize if it is wrong!

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2 years ago

melting, boiling, and bending are considered physical changes, but burning is a chemical change. explain why this is so.

Naya [18.7K]

So, when you make something boiling or melting, its still the same substance. Water doesn't change into something else, just change its state of matter. When you burn something, one substance reacts with another. For example, when you burn carbon in oxygen, you get carbon dioxide. That's the difference.

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3 years ago

List the number of each type of atom on the left side of the equation 2C10H22(l)+31O2(g)→20CO2(g)+22H2O(g)

Leokris [45]

Answer:

20, 44, 62

Explanation:

To find the number of atoms of each element, we multiply coefficient and subscript

For example $5 Ca_1 Cl_2$ contains

5 × 1 = 5 ,Ca atoms and

5 × 2 = 10, Cl atoms

If there is a bracket in the chemical formula

For example $3Ca_3 (P_1 O_4 )_2$

we multiply coefficient × subscript × number outside the bracket to find the number of atoms

(Please note: 3 is the coefficient, and if there is no number given then 1 will be the coefficient )

3 × 3 = 9 , Ca atoms

3 × 1 × 2 = 6, P atoms

3 × 4 × 2 = 24, O atoms are present.

So let us find the number of atoms of each element on the left side of the equation

$2C_{10} H_{22} (l)+31O_2 (g)\Rightarrow 20CO_2 (g)+22H_2 O(g)$

Number of C atoms = 2 × 10 = 20

Number of H atoms = 2 × 22 = 44

Number of O atoms = 31 × 2 = 62

20, 44, 62 are the Answers.

3 0

2 years ago

Are people made up of matter? Do they have mass?

GaryK [48]

Yes. Everything is made up of mass. If it takes up space, it has mass

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3 years ago