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3 years ago

Which of the following is evidence that supports the idea of uniformitarianism?

Chemistry

1 answer:

Radda [10]3 years ago

3 0

<span>D.) Rates of soil erosion are much lower during droughts that last several years.</span>

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Carbon dioxide is a...

Marina86 [1]

Answer: Option B) Pure Substance &

Compound

Explanation:

Carbon dioxide is a compound because it is formed when one carbon atom and two oxygen atoms chemically combined together.

C(s) + O2(g) ---> CO2(g)

Also, CO2 is a pure substance because it is natural and cannot be broken down easily or separated by physical methods.

5 0

2 years ago

A sample of pure calcium fluoride with a mass of 15.0 g contains 7.70 g of calcium. how much calcium is contained in 45.0 g of c

kolbaska11 [484]

In a sample of pure calcium fluoride of mass 15.0 g, 7.70 g of calcium is present. First convert the mass into number of moles as follows:

$n=\frac{m}{M}$

Here, m is mass and M is molar mass.

Molar mass of Ca is 40 g/mol, putting the values,

$n=\frac{7.70 g}{40 g/mol}=0.1925 mol$

Similarly, molar mass of $CaF_{2}$ is 78.07 g/mol thus, number of moles will be:

$n=\frac{15.0 g}{78.07 g/mol}=0.1921 mol$ .

Thus, 0.1921 mol of $CaF_{2}$ have 0.1925 mol of Ca, or 1 mole of $CaF_{2}$ will have approximately 1 mole of Ca.

Now, mass of Ca needs to be calculated in 45.0 g of $CaF_{2}$ . Converting mass into number of moles first,

$n=\frac{45.0 g}{78.07 g/mol}=0.5764 mol$

Thus, number of moles of Ca will also be 0.5764 mol, converting number of moles into mass,

$m=n\times M=0.5764 mol\times 40 g/mol=23.06 g$

Therefore, mass of Ca will be 23.06 g.

6 0

3 years ago

How many of the following postulates of Dalton's atomic theory are still scientifically accepted? I. All atoms of the same eleme

Neko [114]

<h2>The required "options are (II), (III), and (IV)".</h2>

Explanation:

Postulates of Dalton's atomic theory which are scientifically accepted are:

Atoms are indestructible.
Compounds are combinations of different atoms.
A chemical reaction changes the way atoms are grouped together.

Postulates of Dalton's atomic theory which are not accepted scientifically are:

All atoms of the same elements are identical.

The theory states that the atoms of the same element are identical in every aspect but it is now scientifically proved that the same element should differ in their mass which is known as isotopes.

5 0

3 years ago

Predict what kind of energy process happens when Lye, NaOH(s) is put in water and the water gets hot

Grace [21]

What happens is that the sodium solution when put in water reacts and creates thermal energy .

3 0

2 years ago

Read 2 more answers

Which of the following is the Arrhenius definition of an acid?

castortr0y [4]

Arrhenius is a substance that dissociates in water to produce hydrogen ions (H+) and there is a clear answer which coincides with this definition. The correct answer is definitely b. a substance that increases the concentration of hydronium ions when dissolved in water.

5 0

3 years ago