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Korvikt [17]
3 years ago
12

How can we use rocks to determine how an area used to look in the past?

Chemistry
1 answer:
tatiyna3 years ago
8 0
<span>We can use rocks to determine if the animals from to day have changed from the past.
Rocks also help us know if rivers once flowed through an area.
We use them to find out what type of animals live then that are extinct now.</span>
You might be interested in
The following equation represents the type of reaction called
Mazyrski [523]

Answer:

Reduction

Explanation:

Reduction:

Reduction involve the gain of electron and oxidation number is decreased.

Mn⁺⁷ +3e⁻    →    Mn⁴⁺

Mn gets three electrons , its oxidation state reduced from +7 to +4 so Mn gets reduced.

Examples:

Consider the following reactions.

4KI + 2CuCl₂  →   2CuI  + I₂  + 4KCl

the oxidation state of copper is changed from +2 to +1 so copper get reduced.

CO + H₂O   →  CO₂ + H₂

the oxidation state of carbon is +2 on reactant  side and on product side it becomes  +4 so carbon get oxidized.

H₂S + 2NaOH → Na₂S + 2H₂O

The oxidation sate of sulfur is -2 on reactant side and in product side it is also -2 so it neither oxidized nor reduced.

6 0
3 years ago
If an ultraviolet photon has a wavelength of 77.8 nm calculate the energy of one mole ultraviolet photon.
DerKrebs [107]

Answer:

Explanation:

E = (hc)/(λ)

E = (6.624x10^(-27))Js x ((3×10^8)ms^(-1)) /

(77.8x10^(-9)m)

E = 2.55 x 10^(-11) J

7 0
2 years ago
What is an alloy?<br> Answer question 2 if you want.
Anna11 [10]

Answer:

An alloy is a combination of metals or metals combined with one or more other elements. For example, combining the metallic elements gold and copper produces red gold, gold and silver becomes white gold, and silver combined with copper produces sterling silver. Elemental iron, combined with non-

Explanation:

that's what an alloy is all the rocks including gold silver combined with copper  and sterling silver

7 0
3 years ago
Read 2 more answers
1. write the complete chemical symbol for the ion with 14 protons 15 neutrons and 18 electrons
motikmotik

Answer:

1.   Si^{-4}

2.  Co^{+2}

Explanation:

An ion is formed when an atom that is said to be neutral gains or losses electrons.

It is thought that a negative ion (anion) is produced as it gains electrons and a positive ion (cation) is formed when it loses an electron.

Atomic number is the total number of protons and electrons in a neutral atom.

From the information

Protons = 14

electron = 18

Net Charge = no of proton - no of electron

= 14 - 18 = -4

Mass number = 14 + 15 = 29

Thus, the chemical symbol = Si^{-4}

For ion with 27 proton, 32 neutrons and 25 electrons

Net charge = 27 - 25 = +2

Mass number = 27 + 32 = 59

Thus, the chemical symbol = Co^{+2}

6 0
3 years ago
What is the percent yield of ferrous sulfide if the actual yield is 220.0g and the theoretic yield is 275.6?
Amanda [17]
ANSWER yield = 79.83%
3 0
3 years ago
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