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3 years ago

Which geologic time did humans exist

Chemistry

2 answers:

umka2103 [35]3 years ago

4 0

Answer:

Explanation:

because its says mesozoic era

Phantasy [73]3 years ago

3 0

Humans exist in the mesozoic era

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Which best explains why the trend in noble gas boiling points increases down the group?A) increasing dispersion interactions B)

zhenek [66]

Answer:

A) increasing dispersion interactions

Explanation:

Polarizability allows gases containing atoms or nonpolar molecules (for example, to condense. In these gases, the most important kind of interaction produces dispersion forces, attractive forces that arise as a result of temporary dipoles induced in atoms or molecules.

Dispersion forces, which are also called London forces, usually increase with molar mass because molecules with larger molar mass tend to have more electrons, and dispersion forces increase in strength with the number of electrons. Furthermore, larger molar mass often means a bigger atom whose electron distribution is more easily disturbed because the outer electrons are less tightly held by the nuclei.

Because the noble gases are all nonpolar molecules, the only attractive intermolecular forces present are the dispersion forces.

8 0

3 years ago

Does density of water depend on the amount of water present ?

Nitella [24]

No, the denisty of any substance/liquid is always constant, no matter what the volume or mass is. Once the mass g/ volume mL is taken into consideration, the effect of the ammount of liquid given is canceled out. Thus, no matter what your sample is, the density of water will always be 1 g/mL

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3 years ago

The vacoule is most like a ?

Feliz [49]

Animal’s and plant cells

3 0

3 years ago

Read 2 more answers

Which group on the Periodic Table reacts violently with water by igniting hydrogen gas?

Artemon [7]

Answer:

the answer would be Halogens

4 0

3 years ago

When a 3.00 grams sample of a compound containing only c, h, and o was completely burned, 1.17 grams of h2o and 2.87 grams of co

SVEN [57.7K]

Answer:- $CH_2O_2$

Solution:- From given masses of carbon dioxide and water we could calculate the moles that helps to calculate the moles of C and H.

Molar mass of carbon dioxide = 44 gram per mol

molar mass of water = 18.02 gram per mol

From given info, combustion of compound gives 1.17 grams of water and 2.87 grams of carbon dioxide. Let's calculate the moles of these:

$1.17gH_2O(\frac{1mol}{18.02g})$

= $0.0649molH_2O$

Similarly, $2.87gCO_2(\frac{1mol}{44g})$

= $0.0652molCO_2$

One mol of water has two moles of H. So, the moles of H would be two times the moles of water as calculated above.

So, moles of H = 2* 0.0649 = 0.1298 mol

One mol of carbon dioxide contains one mol of C. So, the moles of C would be equal to the moles of carbon dioxide calculated above.

moles of C = 0.0652 mol

Let's convert the moles of H and C to grams so that we could calculate the amount of oxygen present in the sample as:

grams of H in sample = 1.008 x 0.1298 = 0.1308 g

grams of C in sample = 12*0.0652 = 0.7824 g

If we subtract the sum of the masses of C and H from sample mass then it would give as the mass of oxygen since the sample has only C, H and O.

mass of O in sample = 3.00g - (0.1308 g + 0.7824 g)

= 3.00 g - 0.9132 g

= 2.0868 g

Let's convert these grams of oxygen to moles on dividing by it's atomic mass as:

$2.0868gO(\frac{1mol}{15.999g})$

= 0.130 mol O

Now, we have the moles of all the three atoms and we know that an empirical formula is the simplest whole number ratio of the moles of atoms. So, let's calculate the ratio. For this, we divide the moles of each by the least one of them.Looking at the moles, the least value is for carbon. So, let's divide the moles of each by the moles of C as:

C = $\frac{0.0652}{0.0652}$ = 1

H = $\frac{0.1298}{0.0652}$ = 2

O = $\frac{0.130}{0.0652}$ = 2

The ratio of C, H and O is 1:2:2. So, the simplest formula of the compound is $CH_2O_2$ .

3 0

3 years ago