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mylen [45]
3 years ago
14

How much of Earth's atmosphere is made up of nitrogen and oxygen?

Chemistry
2 answers:
Ede4ka [16]3 years ago
8 0
B. CLOSE TO 99% WOULD BE THE CORRECT ANSWER
Archy [21]3 years ago
3 0
<span>The right answer is the option B. Close to 99 percent. The atmosphere is a mixture of gases: nitrogen, oxygen, CO2, H2O, argon, among others. Nitrogen is about 78% and oxygen is about 21%, so they two together constitute about 99 percent of the Earth's atmosphere.</span>
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Question 1 (True/False Worth 2 points)
pochemuha

1) Answer is: False.

Balanced chemical reaction: Pb + AlCl₃ → no reaction.

The reactivity series is a series of metals from highest to lowest reactivity. Metal higher in the reactivity series will displace another.

Aluminium (Al) is higher in activity series than lead (Pb).

That means aluminium (Al) is stronger reducing agent than lead and gives electrons easier.

This series are used to summarize information about the reactions of metals with acids or water, double displacement reactions (more reactive metals displace metals with lower reactivity) and the extraction of metals from their ores.

2) Answer is: Na3PO4 + 3KOH → 3NaOH + K3PO4, because K retains the same charge throughout the reaction.

This chemical reaction is double displacement reaction - cations (K⁺ and Na⁺) and anions (PO₄³⁻⁻ and OH⁻) of the two reactants switch places and form two new compounds.

Na₃PO₄ is sodium phosphate.

KOH is potassium hydroxide.

NaOH is sodium hydroxide.

K₃PO₄ is potassium phosphate.

3) Answer is: Zn + H2SO4 → ZnSO4 + H2.

Single replacement is reaction where neutral element metal or nonmetal become an ion as it replaces another ion in a compound.

In this balanced chemical reaction zinc (Zn) replaces hydrogen (H).

Zinc changes oxidation number from 0 to +2 (this is oxidation) and hydrogen change oxidation number from +1 to 0 (reduction).

4) Answer is: A single replacement reaction takes place because sodium is more reactive than hydrogen.

Balanced chemical reaction:

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g).

Single replacement is reaction where neutral element metal or nonmetal become an ion as it replaces another ion in a compound.

In this balanced chemical reaction sodium (Na) replaces hydrogen (H).

Sodium changes oxidation number from 0 to +1 (oxidation) and hydrogen change oxidation number from +1 to 0 (reduction).

5) Answer is: True.

For example, balanced chemical reaction:

Ca + 2HCl → H₂ + CaCl₂.

Reduction hald reaction: 2H⁺ + 2e⁻→ H₂.

Oxidation half reaction: Ca⁰ → Ca²⁺ + 2e⁻.

In this balanced chemical reaction calcium (Ca) replaces hydrogen (H).

In this chemical reaction, calcium lost two electrons (oxidation, change oxidation number from 0 to +2) and hydrogen gain that two electrons (reduction, change oxidation number from +1 to 0).

6) Answer is: It is a single replacement reaction, and the cations in the two ionic compounds are different.

For example, balanced chemical reaction:  

Ba + MgSO₄ → BaSO₄(s) + Mg.

In this balanced chemical reaction barium (Ba) replaces magnesium (Mg), because barium is higher at activity series.

Sulfate anion (SO₄²⁻) is the same in two ionic compounds, but cations (Mg²⁺ and Ba²⁺) changes.

Single Displacement is reaction where neutral element metal or nonmetal become an ion as it replaces another ion in a compound.  

6 0
3 years ago
When neutrons are added to the atom, the mass number
lianna [129]
The answer is 3) no change

Hope this helps
4 0
3 years ago
How does William Jennings Bryan respond to the criticism that the free and unlimited coinage of silver will disrupt ""business i
kifflom [539]

Answer:

He responded by saying their business definition was far too narrow.

Explanation:

Williams Bryan relates the battle for free silver with the revolution in the United States.

His iconic "Cross of Gold" address ignited the Democratic National Convention in 1896 where he begged the american people not to be "crucified on the cross of gold." He was said this because of the Republicans plan to introduce a firm gold standard and abolish silver coinage.

3 0
3 years ago
An unbalanced chemical equation is shown:
ExtremeBDS [4]

There are 2 Ca, 4 H (2*2) and 4 O (2+2) on the left hand side. So there should be the same number of atoms 2Ca and 4(O+H) on the right hand side.  The reaction is a synthesis (making something new), rather than a decomposition (destroying something).


The answer is Two molecules of Ca(OH)2 should be produced during the synthesis reaction.

4 0
4 years ago
Read 2 more answers
A community in Texas broadcasts public service announcements on tornado safety right before spring. Why is this the most effecti
kvv77 [185]

Answer:

the answer is d.

Explanation:

usually when there is a great variance in storm fronts, the cooler atmosphere and warmer weather on land collide to create more storms...hence tornados, etc....

3 0
3 years ago
Read 2 more answers
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