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melomori [17]
3 years ago
9

2. How have fossils been preserved over millions of years?

Chemistry
2 answers:
just olya [345]3 years ago
8 0

Answer:A fossil is the remains or traces of a once-living plant or animal that was preserved in rock or other material before the beginning of recorded history. ... Fossils of single-celled organisms have been recovered from rocks as old as 3.5 billion years. Animal fossils first appear in rocks dating back about 1 billion years.

Explanation:

kiruha [24]3 years ago
4 0

Five

Five types of fossils: (a) insect preserved in amber, (b) petrified wood (permineralization), (c) cast and mold of a clam shell, (d) pyritized ammonite, and (e) compression fossil of a fern.

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Identify the base-conjugate acid pair in this balanced equation:
Elan Coil [88]
<h3><u>Answer;</u></h3>

NH3/NH4+

<h3><u>Explanation;</u></h3>

From the equation;

NH3(aq)+HNO3(aq)→NH4+(aq)+NO3−(aq)  

NH3 is the base; while NH4+ is the conjugate acid  

HNO3 is the acid; while NO3- is the conjugate base  

  • The conjugate base of a Brønsted-Lowry acid is species that is formed after an acid donates a proton while the conjugate acid of a Brønsted-Lowry base is the species formed after a base accepts a proton.
3 0
3 years ago
Read 2 more answers
The chemical formula for ethanol is C2H601.How many total atoms are in 30 molecules of ethanol?
12345 [234]
There are two carbon atoms in every ethanol molecule, so there would be 60 carbons all together.

I hope this helped you!
3 0
4 years ago
Why the stability of No+ is greater than No?
lyudmila [28]
Because of the protons connected to the Nitrogen oxide group giving it its positive charge.
7 0
3 years ago
The pressure of a 70.0L sample of gas is 600 mm Hg at 20.0C. If the temperature drops to 15.0C and the volume expands to 90.0L,
Mekhanik [1.2K]

Answer:

458.7 mmHg

Explanation:

Step 1:

Data obtained from the question. This includes:

Initial volume (V1) = 70L

Initial pressure (P1) = 600 mmHg

Initial temperature (T1) = 20°C

Final temperature (T2) = 15°C

Final volume (V2) = 90L

Final pressure (P2) =...?

Step 2:

Conversion of celsius temperature to Kelvin temperature.

This is illustrated below:

T(K) = T (°C) + 273

Initial temperature (T1) = 20°C

Initial temperature (T1) = 20°C + 273 = 293K

Final temperature (T2) = 15°C

Final temperature (T2) = 15°C + 273 = 288K

Step 3:

Determination of the new pressure of the gas.

The new pressure of the gas can be obtained by using the general gas equation as shown below:

P1V1/T1 = P2V2/T2

600 x 70/293 = P2 x 90/288

Cross multiply to express in linear form

P2 x 90 x 293 = 600 x 70 x 288

Divide both side by 90 x 293

P2 = (600 x 70 x 288) / (90 x 293)

P2 = 458.7 mmHg

Therefore, the new pressure of the gas is 458.7 mmHg

5 0
3 years ago
Given that the nucleophilic substitution reaction used 5.0 mL of t-pentyl alcohol and 12.0 mL of conc. hydrochloric acid to prod
Vladimir [108]

Answer:

4.90 g

Explanation:

Given that:

volume of t-pentyl alcohol = 5 mL

the standard density of t-pentyl alcohol = 0.805 g/mL

Recall that:

density = mass(in wt) /volume

mass = density × volume

mass = 0.805 g/mL × 5 mL

mass = 4.03 g

Volume of HCl used = 12 mL

The reaction for this equation is shown in the image attached below.

From the reaction,

88.15 g of t-pentyl alcohol reacts with concentrated HCl to yield 106.59 g pf t-pentyl chloride.

4.03 g of t-pentyl alcohol forms,

= \dfrac{106.59 \ g \times 4.03 \ g}{88.15 \ g} of t-pentyl chloride.

Therefore,

Theoretical yield of t-pentyl chloride = 4.90 g

8 0
3 years ago
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