Which of the following are considered pure substances?

Chemistry

1 answer:

Helen [10]3 years ago

8 0

B.Elements

Explanation: they cannot be separated

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What is the reaction that joins thousands of small, identical molecules to form one very long molecule?

34kurt

This is known as polymerisation

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2 years ago

How many sig fig does 0.000925g have

Assoli18 [71]

Answer:

Sig fig 3 decimal 6

Explanation:

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3 years ago

If a solution contains 3 moles/liter of sodium chloride (nacl, made of sodium ions and chloride ions), what is the osmolarity of

valkas [14]

<u>Answer:</u> Osmolarity of the sodium chloride solution is 18 Osmol/L.

<u>Explanation:</u>

Osmolarity is defined as the the concentration of the solution which is expressed as the total number of solution particles present in one liter of solvent.

We are given the molarity of the solution which is 3mol/L and to convert it into osmolarity, we will multiply the number of osmoles that are produced by the solute.

Osmole is defined as the particles that contribute to the osmotic pressure of a solution.

The solute given here is sodium chloride (NaCl). Number of osmoles can be determined by the dissociation of this solvent into ions.

The equation given by the dissociation of NaCl:

$NaCl\rightarrow Na^++Cl^-$

1 mole of sodium chloride produces 2 moles of ions.

So, 3 moles of sodium chloride will produce = (3 × 2) = 6 moles of ions.

Hence, osmolarity of the sodium chloride solution will be $6\times 3mol/L=18Osmol/L$

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3 years ago

What types of evidence do scientists use to determine evolutionary relationships among groups

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There are several things that can help scientists evaluate which category something belongs to. The similarity in features is one of them. If two skulls looked alike, they were probably species of the same evolutionary category. For example say humans and monkeys rather than humans and dogs.
Similarly fossils have helped scientists categorise species. Study of the chromosomes (in cases with available chromosomes) can help scientists figure out a lot about the subjects and categorise them.

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2.50 g of Zn is added to 5.00 g of HCl

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Zn+2HCl ----> 2ZnCl2 + H2

For 2.50 g of Zn

Mass per mol = 2.50/molar mass of Zn = 2.50/65.38 = 0.0382 g/mol
There are two moles of ZnCl2 and total mass = 2*0.0382*molar mass of ZnCl2 = 2*0.0382*136.286 = 10.42 g

For 2 g of HCl

Mass per mol = 2/2*molar mass of HCl = 2/ (2*36.46) = 0.0274 g/mol
For the two moles of ZnCl2, mass produced = 2*0.0274*136.286 = 7.48 g

It can be noted that 2 g of HCl produced less amount of ZnCl and thus it is the limiting reagent.

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2 years ago