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3 years ago

Which of the following is true about fossils?

Chemistry

2 answers:

Agata [3.3K]3 years ago

7 0

Answer:C

Explanation:

nikitadnepr [17]3 years ago

4 0

Answer:

The answer is <u>B</u><em>!</em>

Explanation:

if they are lower this means that they have been on the ground longer there for older

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Acidis are,which means that they "eat away"at other materials

alexandr1967 [171]

Acids are corrosive, which means they 'eat away' at other materials.

5 0

3 years ago

PLZ HELP!!!!!!!!!!!!!

gregori [183]

117.22 g are needed to react with an excess of Fe2O3 to produce 156.2 g of Fe.

Explanation:

Moles of Fe = Mass of Fe in grams / Atomic weight of Fe

= 156.2 / 55.847

Moles of Fe = 2.79.

The ratio between CO and Fe id 3 : 2.

Moles CO needed = 2.79 * (3 / 2)

= 4.185.

To calculate Atomic weight of CO,

Atomic weight of carbon = 12.011

Atomic weight of oxygen= 15.9994

Atomic weight of CO = 12.011 + 15.9994 = 28.01 g / mol.

Mass of CO = 4.185 * 28.01 = 117.22 g.

5 0

3 years ago

The enzyme, carbonic anhydrase, is a large zinc-containing protein with a molar mass of 3.00 x10^4 g/mol. Zn is 0.218% by mass o

tia_tia [17]

The mathematical expression for mass percent is given by:

$Mass percent = \frac{mass of the compound}{molar mass of the compound}\times 100$

Put the values,

$0.218 percent of zinc = \frac{mass of zinc}{3.00 \times 10^{4} g/mol}\times 100$

mass of zinc = $0.218 \times (3\times 100) g$

= $0.654 \times 100 g$ or 65.4 g

Now, number of moles of zinc = $\frac{given mass in g}{molar mass of zinc}$

= $\frac{65.4 g}{65.38 g/mol}$

= 1.00 mole

Number of atoms of zinc is calculated by the Avogadro number.

Now, according to mole concept

$6.022\times 10^{23}$ molecules of enzyme consists of $6.022\times 10^{23}$ atoms of zinc

So, 1 molecule of enzyme contains = $\frac{6.022\times 10^{23}atoms of zinc}{6.022\times 10^{23} }$

= 1 atom of zinc.

Hence, every carbonic anhydrase molecule consists of 1 atom of zinc.

5 0

3 years ago

It was calculated that 4.3mL of 0.417 M HCl is required to titrate 11.9 mL of 0.151 M Mg(OH)2. Show evidence 2 HCl(aq) + Mg(OH)2

Lapatulllka [165]

Answer:

See explanation.

Explanation:

Hello,

In this case, for the described chemical reaction:

2 HCl(aq) + Mg(OH)2(aq) → MgCl2(aq) + 2 H2O(l)

We can notice there is a 2:1 molar ratio between the moles of hydrochloric acid and magnesium hydroxide, therefore, at the equivalence point:

$n_{HCl}=2*n_{Mg(OH)_2}$

And in terms of volumes and concentrations we verify:

$V_{HCl}M_{HCl}=2*V_{Mg(OH)_2}M_{Mg(OH)_2}$

So we use the given data to proof it:

$4.3mL*0.417M=2*11.9mL*0.151M\\1.793=3.594$

Therefore, we can conclude the data is wrong by means of the 2:1 mole ratio that for sure was not taken into account. This is also supported by the fact that normalities are actually the same, but the nomality of magnesium hydroxide is the half of the hydrochloric acid normality since the acid is monoprotic and the base has two hydroxyl ions.

Best regards.

4 0

3 years ago

Why does the particle of water at 0 degree celcius have more energy as cimparrd to the particles in ice at the same temperature?

jekas [21]

There is Kinetic energy involved in the state something is in. The molecules in a liquid are moving around quicker than those in a solid.

That's one reason.

The ice requires energy to melt. Bonds must be broken to get from a solid to a liquid.

5 0

3 years ago