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3 years ago

What organisims allowed for the build up of oxygen in the atmosphere?

Chemistry

2 answers:

Maru [420]3 years ago

5 0

Answer:

The answer is tiny organisms known as cyanobacteria, or blue-green algae. These microbes conduct photosynthesis: using sunshine, water and carbon dioxide to produce carbohydrates and, yes, oxygen.

:-))

Margarita [4]3 years ago

4 0

Answer:

Cyanobacteria

Explanation:

The answer is tiny organisms known as cyanobacteria, or blue-green algae.

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#1: How are the elements arranged in the modern periodic table?

Alekssandra [29.7K]

1- The correct answer is C :

the elements arranged in the modern periodic table by increasing atomic number.

The explanation:

-The elements in the periodic table are arranged to increase the atomic number. All of these elements display several other trends and we can use the periodic law and table formation to predict their chemical, physical, and atomic properties.

2- The correct answer is C:

strontium, magnesium, calcium, beryllium are the elements which have similar properties.

The explanation:

-strontium, magnesium, calcium, beryllium, these belong to the alkaline earth metal group.

Because the outer electron structure in all of these elements is similar, they all have somewhat similar chemical and physical properties .

3- The correct answer is A :

Potassium

The explanation:

-The elements potassium and sodium have similar chemical properties because they have the same number of valence electrons and form +1 ions.

4- The correct answer is D

The explanation:

Mendeleev didn't include helium, neon, and argon in his periodic table because these elements had not yet been discovered.

5- The correct answer is B:

The periodic law describes trends seen across periods within the periodic table.

The explanation:

When the chemical elements are arranged, there is a pattern called the “periodic law” in their properties, in which elements in the same column (group) have similar properties

4 0

3 years ago

Read 2 more answers

Which arrangement of electrons is correct? Help please its timed!!!

postnew [5]

Answer:

Explanation:

According to all the principles of filling it is d

8 0

3 years ago

Write the balanced equation for the reaction of aqueous Pb ( ClO 3 ) 2 Pb(ClO3)2 with aqueous NaI . NaI. Include phases. chemica

FinnZ [79.3K]

Answer: The mass of precipitate (lead (II) iodide) that will form is 119.89 grams

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}$

Molarity of NaI solution = 0.130 M

Volume of solution = 0.400 L

Putting values in above equation, we get:

$0.130M=\frac{\text{Moles of NaI}}{0.400L}\\\\\text{Moles of NaI}=(0.130mol/L\times 0.400L)=0.52mol$

The balanced chemical equation for the reaction of lead chlorate and sodium iodide follows:

$Pb(ClO_3)_2(aq.)+2NaI(aq.)\rightarrow PbI_2(s)+2NaClO_3(aq.)$

The precipitate (insoluble salt) formed is lead (II) iodide

By Stoichiometry of the reaction:

2 moles of NaI produces 1 mole of lead (II) iodide

So, 0.52 moles of NaI will produce = $\frac{1}{2}\times 0.52=0.26mol$ of lead (II) iodide

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Moles of lead (II) iodide = 0.26 moles

Molar mass of lead (II) iodide = 461.1 g/mol

Putting values in above equation, we get:

$0.26mol=\frac{\text{Mass of lead (II) iodide}}{461.1g/mol}\\\\\text{Mass of lead (II) iodide}=(0.26mol\times 461.1g/mol)=119.89g$

Hence, the mass of precipitate (lead (II) iodide) that will form is 119.89 grams

4 0

3 years ago

A green shirt looks green to you because

musickatia [10]

Search Results
Featured snippet from the web
A green shirt looks green because light reflects off of the green shirt. ... Visible light on the electromagnetic spectrum is found in between infrared waves and ultraviolet waves.

3 0

3 years ago

Which of the following formulas represents an ionic compound?

Marta_Voda [28]

Answer:

BaI2

Explanation:

Hello, since the electronegativity of Barium and Iodine are 0.89 and 2.66, respectively, the difference is 1.77, so the bond is ionic.

Best regards.

5 0

3 years ago