Please help 19.0 kg/0.021 m^3

which of the following correctly identifies the composition of an oxygen atom? A.8 protons, 8 electrons, and 8 neutrons. B.6 pro

Ulleksa [173]

You can answer this question by getting the atomic number and atomic mass of Oxygen from a periodic table. There you will find that the atomic number is 8, that means, by definition, that it has 8 protons. This is, because atomic number is defined as the number of protons of an element. Given that the atom is neutral, that implies that the atoms have the same number of electrons than protons. So you already know that the oxygen atoms has 8 protons and 8 electrons. The number of neutrons can vary, which is what defines the isotopes. Given that the atomic mass of oxygen is 15.999, that means that most atoms of oxygen has 8 neutrons (8 protons +8 neutrons = 16 atomic mass). But you can not be sure that a specific atom of oxygen has 8 neutrons, nevertheless, given that the other options are discarded (because they do not have 8 protons and 8 electrons), the only correct answer is the option A. 8 protons, 8 electrons, and 8 neutrons.

8 0

3 years ago

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When a substance undergoes a chemical change, the product exhibits different physical properties than the starting material. Des

elena55 [62]

Answer:

I) Change in solubility

II) Change in boiling point

III) Change in colour

Explanation:

A chemical change involves formation of new products and is not reversible.

So, once two liquid solutions are mixed and a chemical change takes place, the new product will have the following:

- a new solubility rate, i.e it will dissolve at a rate different from the two liquid solution

- a new boiling point i.e it takes a new point at which its molecules liberate to yield vapour

- a new colour might be detected, as the individual solution each has its own colour

6 0

3 years ago

Burning a compound of calcium, carbon, and nitrogen in oxygen in a combustion train generates calcium oxide , carbon dioxide , n

mylen [45]

The question is incomplete, here is the complete question:

Burning a compound of calcium, carbon, and nitrogen in oxygen in a combustion train generates calcium oxide (CaO), carbon dioxide $(CO_2)$ , nitrogen dioxide $(NO_2)$ , and no other substances. A small sample gives 2.389 g CaO, 1.876 g $CO_2$ , and 3.921 g $NO_2$ Determine the empirical formula of the compound.

Answer: The empirical formula for the given compound is $CaCN_2$

Explanation:

The chemical equation for the combustion of compound having calcium, carbon and nitrogen follows:

$Ca_xC_yN_z+O_2\rightarrow CaO+CO_2+NO_2$

where, 'x', 'y' and 'z' are the subscripts of calcium, carbon and nitrogen respectively.

We are given:

Mass of CaO = 2.389 g

Mass of $CO_2=1.876g$

Mass of $NO_2=3.921g$

We know that:

Molar mass of calcium oxide = 56 g/mol

Molar mass of carbon dioxide = 44 g/mol

Molar mass of nitrogen dioxide = 46 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 1.876 g of carbon dioxide, $\frac{12}{44}\times 1.876=0.5116g$ of carbon will be contained.

For calculating the mass of nitrogen:

In 46 g of nitrogen dioxide, 14 g of nitrogen is contained.

So, in 3.921 g of nitrogen dioxide, $\frac{14}{46}\times 3.921=1.193g$ of nitrogen will be contained.

For calculating the mass of calcium:

In 56 g of calcium oxide, 40 g of calcium is contained.

So, in 2.389 g of calcium oxide, $\frac{40}{56}\times 2.389=1.706g$ of calcium will be contained.

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Calcium = $\frac{\text{Given mass of Calcium}}{\text{Molar mass of Calcium}}=\frac{1.706g}{40g/mole}=0.0426moles$

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{0.5116g}{12g/mole}=0.0426moles$

Moles of Nitrogen = $\frac{\text{Given mass of Nitrogen}}{\text{Molar mass of Nitrogen}}=\frac{1.193g}{14g/mole}=0.0852moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.0426 moles.

For Calcium = $\frac{0.0426}{0.0426}=1$

For Carbon = $\frac{0.0426}{0.0426}=1$

For Nitrogen = $\frac{0.0852}{0.0426}=2$

Step 3: Taking the mole ratio as their subscripts.

The ratio of Ca : C : N = 1 : 1 : 2

Hence, the empirical formula for the given compound is $CaCN_2$

3 0

3 years ago

A geologist measures the height of a mountain.the height is 5.3489km what is the height in meters write your answer in decimal

Xelga [282]

Height of a mountain is 5348.9 meter.

1 kilometer is equal to 1000 meter.

The meter, symbol m, is the primary unit of period in the international system of gadgets, although its prefixed paperwork also are used relatively regularly.

A meter is a general metric unit identical to about three feet 3 inches. This means that a meter is part of the metric gadget of dimension. Guitars, baseball bats, and backyard sticks are examples of items which might be approximately one meter lengthy. Meters also are used to measure distances in races, inclusive of strolling and swimming.

Meter readings tell power suppliers how a lot gasoline and energy you are the use of. In case you do not give your provider meter readings they may have to guess your usage. You typically turn out to be paying too much or too little while this occurs.

Learn more about meter here:- brainly.com/question/218459

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7 0

1 year ago

What happens when chemical bonds break and new bonds form

zheka24 [161]

Answer:

Chemical reactions make and break the chemical bonds between molecules, resulting in new materials as the products of the chemical reaction.

Explanation:

Breaking chemical bonds absorbs energy, while making new bonds releases energy, with the overall chemical reaction being endothermic or exothermic.

5 0

3 years ago