Which element had the longest effect on human history?

There are approximately 1.73 x 10^25 oxygen atoms in 7.20 moles of H2SO4. This is calculated by determining the number of oxygen atoms per mole of H2SO4 (4), then multiplying that by the number of moles (7.20) and by Avogadro's number.

The student is asking about the number of oxygen atoms in 7.20 moles of H2SO4. The molar mass of H2SO4 is approximately 98.09 g/mol and it is composed of two hydrogen atoms, one sulfur atom, and four oxygen atoms.

One mole of H2SO4 contains 4 moles of oxygen, so 7.20 moles of H2SO4 would contain 7.20 * 4, which equals 28.8 moles of oxygen. Since a mole of any substance contains Avogadro's number (6.022 x 10^23) of entities (atoms, in this case), 28.8 moles of oxygen atoms would contain 28.8 * 6.022 x 10^23 oxygen atoms.

Doing the math, we find that there are approximately 1.73 x 10^25 oxygen atoms in 7.20 moles of H2SO4.

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Answer:

40 Thousands

Explanation:

This is a multiplication account. Although the value seems very high, you can first ignore the name "Thousands" by multiplying only the decimal numbers and adding "Thousands" at the end.

Thus:

10x4 = 10 + 10 + 10 + 10 ----> 40 Thousands

What we can actually do is to find the number of moles of Ca.

moles Ca = 0.72 g / (40.08 g/mol) = 0.018 mol

From the given choices, we can all see that there are 1 mol of compound per 1 mole of Ca. Therefore the actual moles of compound is also 0.018 mol. From this, calculate the mass and the answer is the one which will give 2 g.

Answer:

D. CaCl2

A chemical reaction includes two or more reactants and the products separated by an arrow.  The reactants are separated each other by a plus sign and the same in between the products.

A chemical reaction is the combination of two or more reactants or reacting species. Through effective collision,  they form products.

The reactants and products are separated each other by a right arrow. Let A and B the reactants and C be the product. Then, the reaction is written as below:

A + B [tex]\rightarrow[/tex] C.

Sometimes the reactions can be reversible where we can use a reversible arrow ' ⇄ ' which indicates that the products can in turn convert into the reactants.

Sometimes an equal sign is used to indicate the product side in a reaction but it is not scientific and an arrow is used more properly.

Therefore, the symbol used to separate reactants from each other r products from each other is a plus sign. Hence, D is correct.

To find more about chemical reactions, refer the link below:

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Final answer:

In a chemical equation, reactants are written on the left hand side and products on the right hand side. The arrow is used to indicate the direction of the reaction, and plus signs (+) separate individual reactant and product formulas.

Explanation:

A chemical equation uses symbols to describe a chemical reaction. In a chemical equation, reactants are written on the left hand side of the equation and the products on the right. The arrow is used to show the direction of the reaction. Plus signs (+) separate individual reactant and product formulas.

Pumping air into ice cream increases its volume, making consumers pay more for a lower actual amount of ice cream by volume. This is why ice cream with added air is more expensive. The correct answer is option C) After air is pumped into ice cream, the mixture occupies a greater volume than the ice cream alone did.

Ice cream manufacturers often pump air into the ice cream before packaging it. This practice makes ice cream more expensive to the consumer because the resulting mixture occupies a greater volume than the ice cream alone did. Therefore, consumers are paying more for a lower actual amount of ice cream by volume.

Let's explore why this is the case:

Final answer:

Crust forming on lava showcases how heat removal can induce a state change. Lava is defined as a molten rock that is from a volcano or from a fissure in the surface of the earth.

Explanation:

Crust forming on the surface of lava illustrates the principle that removing heat from a system may result in a change in state. As lava cools and solidifies on the Earth's surface, the heat is extracted from the molten rock, causing it to transition from a liquid state to a solid state, forming new crust. This process exemplifies how altering the thermal energy within a system leads to a change in the physical state of the material.

Acetic acid is highly soluble in water due to its polar nature, while olive oil's nonpolar properties result in low solubility.

Acetic acid is highly soluble in water due to its polar nature, allowing it to interact with water molecules through hydrogen bonding. On the other hand, olive oil is nonpolar and lacks the ability to form significant interactions with water, resulting in low solubility.

The presence of a carboxylic acid group in acetic acid facilitates its solubility in water by enabling hydrogen bonding with water molecules. In contrast, the predominantly nonpolar nature of olive oil limits its solubility in water due to a lack of interactions with water molecules.

Overall, the polar vs. nonpolar properties of acetic acid and olive oil play a crucial role in determining their solubility in water.

Particles move independently of one another and are widely spaced.

Answer:

True

Explanation:

Answer: During a chemical change, different atoms are introduced after the change than before the change.

Explanation: Chemical reactions are defined as the reaction in which two or more substances react to form a new substance. The composition of the reactants change completely when the product is formed in a chemical reaction.

For example: Formation of rust when iron metal is exposed to air and moisture for a long time.

Equation follows:

[tex]2Fe(s)+\frac{3}{2}O_2(g)\rightarrow Fe_2O_3[/tex]

So, During a chemical change, different atoms are introduced after the change than before the change.