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kotegsom [21]
4 years ago
13

List at least 15 important events in the science of Astronomy. Include a description of the event including the year and what cu

lture made the contribution.
Chemistry
2 answers:
lbvjy [14]4 years ago
7 0
The Big Bang probably occurred.
~30,000 B.C. North America Asian hunter-gatherers had crossed over the frozen Bering Strait to become first humans in North America.
~10,000 B.C. South America Those who crossed over on Bering Strait into North America had traveled as far south as Argentina by this point.
~6,000 B.C. Europe End of land bridge between Britain and continental Europe. Britain becomes an island.
~4,500 B.C. Brittany (France) The megalithic structures of Carnac were built.
~3,500 B.C. Wales Pentre Ifan is built.
~3,200 B.C. Ireland The Newgrange tomb is built.
Alecsey [184]4 years ago
5 0
Jesus is always the answer
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O Which of the following determines the
lana66690 [7]

Answer:

A. atomic number

Explanation:

the mass number alone cannot uniquely identify an element. But the number of protons in the nucleus identifies it uniquely. In addition, if the atom is neutral, then the atomic number also equals the number of electrons in its orbitals.

3 0
2 years ago
16.0 grams of oxygen gas reacted with 80.0 grams nitrogen monoxide gas producing 25.0 grams of nitrogen dioxide gas in the lab.
Anon25 [30]

Answer:

Limiting reactant  = O₂

Excess reactant = NO

Theoretical yield of NO₂ = 46 g

Mass of excess reactant = 30 g

<h3 />

Explanation:

O₂ + 2NO → 2NO₂

Mole ratio for the reaction is;

1 : 2 → 2

mass of O₂ = 16 g

mass of NO = 80 g

mass of NO₂ = 25 g

molecular weight  of O₂ = 32 g/mol

molecular weight  of NO = 30 g/mol

molecular weight  of NO₂ = 46 g/mol

molar mass of O₂ = mass ÷ molecular weight = 16 g ÷ 32 g/mol = 0.5 mol

molar mass of NO = mass ÷ molecular weight = 80 g ÷ 30 g/mol = 2.67 mol

Since, 1 mole of O₂ requires 2 moles of NO for the combustion reaction, 0.5 mole shall require 1 mole of NO for the reaction. Thus, O₂ is the limiting reactant and NO is the excess reactant as it has an excess of 2.67 mol - 1 mol = 1.67 mol.

<h3>Theoretical yield of NO₂</h3><h3 />

1 mole of O₂ shall yield 2 moles of NO₂

Thus, 0.5 mole of O₂ shall yield 1 mole of NO₂

mass of NO₂ = molecular weight * molar mass = 46 g/mol * 1 mole = 46 g

<h3>Mass of Excess Reactant</h3>

1 mole of O₂ shall react with 2 moles of NO

Thus, 0.5 mole of O₂ shall yield 1 mole of NO

mass of NO = molecular weight * molar mass = 30 g/mol * 1 mole = 30 g

5 0
3 years ago
I need help asap thank u
UNO [17]
It is b, i learned this last year hope this helps
4 0
3 years ago
It's believed by many that a good way to vandalize a car is to pour sugar (sucrose) in its gas tank. the sugar is believed to di
Artyom0805 [142]
Answer is: in this experiment it is best to use some liquid alkanes (for example hexane), because gasoline<span> consists of hydrocarbons with between four and twenty carbon atoms</span>. Gasoline is a mixture <span> of many different hydrocarbons: </span><span>alkanes (paraffins), cycloalkanes  and alkenes (olefins).</span>
7 0
4 years ago
What is the pH of a solution with a hydrogen-ion concentration ([H+]) of 8.7 x 10-6M? Is this acidic or basic?
Nimfa-mama [501]

Answer:

pH = 5.06, solution is acidic

Explanation:

pH = - log [H+]

we are given, [H+] as  8.7 x 10^-6M

Therefore;

pH = - log (8.7 x 10^-6 M)

    = 5.06

pH = 5.06

But a solution with a pH of, 1-6 is acidic, while a pH of 7 is neutral and that of 8-14 is basic.

Thus; a pH of 5.06 is acidic

3 0
4 years ago
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