true or false
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true or false

Answer: The given number is already an integer.

Explanation:

Integer is defined as a whole number which is not a fraction. This number can be positive, negative or zero.

Decimal numbers are not considered as integers. They are rounded off to write an integer.

For Example: 4, -2 and 0, all are considered as integers.

We are given a number having value 470,809 miles. The number is already a whole positive number.

Thus, the given number is already an integer.

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.

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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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

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.

Final answer:

A catalyst is used to speed up the flubber experiment. Borax is a possible catalyst that can accelerate the formation of flubber by lowering the activation energy and promoting the reaction between polyvinyl acetate glue and borax.

Explanation:

A catalyst is a substance that speeds up a chemical reaction without being consumed in the process. In the flubber experiment, the professor most likely used a catalyst to accelerate the formation of flubber. One possible catalyst that could be used in this experiment is sodium borate, also known as borax.

The reaction between polyvinyl acetate glue and borax in the presence of water leads to the formation of cross-linked polymer chains, creating the bouncy and stretchy substance known as flubber. The borax acts as a catalyst by lowering the activation energy of the reaction, allowing it to occur more quickly.

By using a catalyst, the professor was able to demonstrate the reaction between the glue and borax more efficiently, saving time and ensuring a successful flubber formation.

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.

Answer:

True

Explanation:

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:

The neutron number is not unique to each element.

Explanation:

The correct option is C. neutron number.

While proton number (also known as atomic number) and atomic number are unique to each element, representing the number of protons in the nucleus of an atom, the neutron number can vary for different isotopes of the same element.

The chemical symbol is also unique to each element, representing an abbreviation used to identify the element or its atoms. Each element on the periodic table is assigned a unique chemical symbol.

The correct answer is C. Neutron number is NOT unique to each element.

Each element in the periodic table is defined by its atomic number, which is the number of protons in the nucleus of an atom of that element. The atomic number is unique to each element and determines its position in the periodic table. For example, hydrogen has an atomic number of 1, meaning it has one proton in its nucleus, and helium has an atomic number of 2, meaning it has two protons.

The proton number, which is another term for the atomic number, is also unique to each element. Therefore, options A and B (proton number and atomic number) are unique to each element.

On the other hand, the neutron number is not unique to each element. Different isotopes of the same element have different numbers of neutrons. For instance, the most common isotope of carbon is carbon-12, which has 6 neutrons, but there is also a carbon-13 isotope, which has 7 neutrons, and a carbon-14 isotope, which has 8 neutrons. All these isotopes are still carbon because they have the same atomic number (6 protons), but they have different neutron numbers.

The chemical symbol is a shorthand way to represent an element and is also unique to each element. For example, the chemical symbol for carbon is C, for oxygen is O, and for hydrogen is H. These symbols do not change regardless of the isotope or the number of neutrons present in the nucleus.