The marathon covers 26 miles, 285 yards. Express this distance in kilometers.(1 km= 0.6214 miles, 1 inch = 2.54 centimeters)
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Answer is (4) - CH₃CH₂OH and CH₃OCH₃.

Both CH₃CH₂OH and CH₃OCH₃ have same molecular formula as C₂H₆O. But CH₃CH₂OH is an alcohol and CH₃OCH₃ is an ether.

Although two compounds have a same molecular formula, the atomic arrangement of those compounds differs from each other.

Hence, CH₃CH₂OH and CH₃OCH₃ are isomers of the formula C₂H₆O.

Due to the different arrangement of atoms, both compounds have different chemical and physical properties.

Explanation:

In solids, molecules are held together due to strong intermolecular force of attraction between them. These molecules do not move past each other as they are fixed at their position. As a result, solids have definite shape and volume.

In liquids, molecules are less tightly held as a result the molecules are able to move and hence they slide past each other. Liquids do not have fixed shape and volume.

In gases, molecules are held by weak Vander waal forces. Therefore, they move rapidly from one place to another with more collisions.

Thus, we can conclude that liquid is the phase of matter which consists of particles that are held together but have the ability to flow past each other.

The substances that can't be separated into simpler substances or converted into other substances by chemical processes are elements. They are fundamental substances and cannot be changed into other elements through chemical processes. The correct answer to the given question is option a. elements

The answer to your question is a. elements. In chemistry, elements are substances that cannot be separated into simpler substances or converted into another substance by chemical processes.

This is what makes them fundamental substances. Chemical processes can change compounds, solutions, suspensions, and colloids into different substances, but they cannot change an element into a different element. For example, hydrogen is an element that cannot be converted into any other element through chemical processes. It is fundamentally hydrogen.

The correct answer to the given question is option a. elements

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Ans: The products have lower potential energy than the reactants, and the enthalpy change is negative.

In general, chemical reactions can be broadly classified into two categories:

1) Exothermic

2) Endothermic

Exothermic reactionsproceed with the evolution of heat. Here, the reactants have a higher potential energy which is released as the reaction progresses to form products. Consequently, the products are in a lower energy state. Since energy is released, the enthalpy change will be negative.

In contrast, endothermic reactions proceed with the absorption of heat. Here,the products will be in a higher energy state. Since energy is absorbed, the enthalpy change will be positive.

Answer:

Marie Curie, née Maria Salomea Skłodowska, (born November 7, 1867, Warsaw, Congress Kingdom of Poland, Russian Empire—died July 4, 1934, near Sallanches, France), Polish-born French physicist, famous for her work on radioactivity and twice a winner of the Nobel Prize.

Explanation:

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Answer:

Marie Curie is the one who earned the nobel prize twice for her work with radioactivity