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aliina [53]
3 years ago
12

How many elements are in the periodic table?

Chemistry
2 answers:
gogolik [260]3 years ago
5 0

There are <u>118</u> elements.

ZanzabumX [31]3 years ago
3 0
I think there’s 118 elements
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Pesticide concentrations in the Rhine River between Germany and France between 1969 and 1975 averaged 0.55 mg/L of hexachloroben
sertanlavr [38]

Answer:

1.93×10⁻³ mmoles/L of C₆Cl₆; 1.58×10⁻⁴ mmoles/L of C₁₂H₈Cl₆O; 3.51×10⁻³ mmoles/L of C₆H₆Cl₆

Explanation:

We have to find out the molar mass of each pesticide to calculate the moles, and then the milimoles

C₆Cl₆ → 12. 6 + 35.45 .6 = 284.7 g/m

C₁₂H₈Cl₆O →  12 . 12 + 8.1 + 35.45 .6 + 16 = 380.7 g/m

C₆H₆Cl₆ → 12.6 + 6.1 + 35.45 .6 = 290,7 g/m

Let's convert mg to g (/1000)

0.55 mg / 1000 = 5.5×10⁻⁴ g

0.060 mg / 1000 = 6×10⁻⁵ g

1.02 mg / 1000 = 1.02×10⁻³ g

Now we can know the moles (mass / molar mass)

5.5×10⁻⁴ g / 284.7 g/m = 1.93×10⁻⁶ moles of C₆Cl₆

6×10⁻⁵ g / 380.7 g/m = 1.58×10⁻⁷ moles of C₁₂H₈Cl₆O

1.02×10⁻³ g / 290,7 g/m = 3.51×10⁻⁶ moles of C₆H₆Cl₆

Milimoles = Mol . 1000

1.93×10⁻⁶ . 1000 = 1.93×10⁻³ mmoles of C₆Cl₆

1.58×10⁻⁷ . 1000 = 1.58×10⁻⁴ mmoles of C₁₂H₈Cl₆O

3.51×10⁻⁶ . 1000 = 3.51×10⁻³ mmoles of C₆H₆Cl₆

6 0
3 years ago
If you examined the human body on a chemical composition basis, which of the following combinations of elements would be most co
Harlamova29_29 [7]

Answer:

(C) O, C, H, N

Explanation:

<u>Roughly 96% of mass of human body is made up of four elements which are oxygen, carbon, nitrogen and hydrogen.</u>

Oxygen and hydrogen are predominantly found in the water, which makes up about 60% of body's weight. Carbon is synonymous with the life. The central role of carbon is due to fact that it has four bonding sites which allow for building of long and complex chains of the molecules. Moreover, these carbon bonds can be formed and also be broken with amount of energy which makes life alive. Nitrogen is found in organic molecules, including amino acids which make up the proteins, and nucleic acids which make up the DNA.

5 0
3 years ago
Which of the following is part of photosynthesis, but not part of cellular respiration?
Licemer1 [7]

Answer:

A

Explanation:

  • plants need sunlight to eat. so that's why

8 0
2 years ago
Describe relationships between molecules atoms and a grain of sugar
Contact [7]

The relationships between molecules atoms and a grain of sugar is the combination of atoms to molecules and the combination of molecules to a compound.

<u>Explanation:</u>

Atom is the foreground to the existence of matter and matter is just another huge combination of atoms. The presence of neutrons, protons and electrons are the important structures of atoms and these atoms are merged to build a molecule.

The relationships between molecules atoms and a grain of sugar is the combination of atoms to molecules and the combination of molecules to a compound.

Molecules are brought together with positive and negative parts of protons and electrons to form bonds and compounds. And compounds come up with elements which connects all these atoms.

3 0
2 years ago
Are all single bonds sigma bonds?
Nikolay [14]
Single bonds are those that bond with one atom, and sigma bonds are the strongest type of covalent bonds that are single bonded. 

That means NO, not all single bonds are sigma bond, but all sigma bonds are single bonds. 
6 0
3 years ago
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