During an experiment, a student observes the formation of a precipitate. Why does this indicate that a chemical reaction is likely occurring? 1)A solid forms, and there is a change of color. 2)A gas forms, and there is a change of color. 3)A solid forms, and light is emitted. 4)A gas forms, and light is emitted.

According to the mole concept, there are 76.94 g in 2.4 moles of sulfur atoms.

What is a mole?

Mole is defined as the unit of amount of substance . It is the quantity measure of amount of substance of how many elementary particles are present in a given substance.

It is defined as exactly 6.022×10²³ elementary entities. The elementary entity can be a molecule, atom ion depending on the type of substance. Amount of elementary entities in a mole is called as Avogadro's number.

It is widely used in chemistry as a suitable way for expressing amounts of reactants and products.For the practical purposes, mass of one mole of compound in grams is approximately equal to mass of one molecule of compound measured in Daltons. Molar mass has units of gram per mole . In case of molecules, where molar mass  in grams present in one mole  of atoms is its atomic mass.

Mass is found out by number of moles by formula , mass=number of moles×molar mass

Substitution in above formula gives, mass=2.4×32.06=76.94 g

Thus, there are 76.94 g in 2.4 moles of sulfur.

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Answer:

Explanation:

In chemistry, elements and compounds are distinct types of substances with fundamental differences:

**Elements:** Elements are the simplest and purest substances in chemistry, consisting of only one type of atom. Atoms are the building blocks of matter, and each element is defined by the number of protons in the nucleus of its atoms. Elements are listed on the periodic table, where each element is represented by a unique chemical symbol. They cannot be broken down into simpler substances by chemical reactions. For example, oxygen (O), carbon (C), and gold (Au) are all elements.

**Compounds:** Compounds, on the other hand, are substances formed when two or more different elements chemically combine in fixed ratios. These combinations involve chemical bonds, where atoms share electrons or transfer them to achieve stable electron configurations. Compounds have unique chemical formulas that represent the types and numbers of atoms in the compound. Unlike elements, compounds can be broken down into their constituent elements through chemical reactions. A classic example is water (H2O), which is a compound composed of two hydrogen atoms and one oxygen atom.

In summary, elements are pure substances composed of identical atoms, while compounds are substances formed by the chemical combination of two or more different elements in fixed ratios. Elements are found on the periodic table and cannot be broken down further by chemical means, whereas compounds can be decomposed into their constituent elements through chemical reactions.

Answer:

Explanation:

In chemistry, elements and compounds are distinct types of substances with fundamental differences:

**Elements:** Elements are the simplest and purest substances in chemistry, consisting of only one type of atom. Atoms are the building blocks of matter, and each element is defined by the number of protons in the nucleus of its atoms. Elements are listed on the periodic table, where each element is represented by a unique chemical symbol. They cannot be broken down into simpler substances by chemical reactions. For example, oxygen (O), carbon (C), and gold (Au) are all elements.

**Compounds:** Compounds, on the other hand, are substances formed when two or more different elements chemically combine in fixed ratios. These combinations involve chemical bonds, where atoms share electrons or transfer them to achieve stable electron configurations. Compounds have unique chemical formulas that represent the types and numbers of atoms in the compound. Unlike elements, compounds can be broken down into their constituent elements through chemical reactions. A classic example is water (H2O), which is a compound composed of two hydrogen atoms and one oxygen atom.

The minimum energy required to start a reaction is called activation energy (A.E.).

(Option C)

What is activation energy?

Activation energy is the energy barrier that reactant molecules must overcome to transform into products during a chemical reaction.

It is the energy difference between the energy levels of the reactants and the transition state on the reaction's potential energy diagram.

Enthalpy (E1 and E2) and heat of reaction are related to the energy changes during the course of a reaction but are not directly related to the energy barrier required to initiate the reaction.

Enthalpy (H) refers to the total heat content of a system, while heat of reaction (ΔH) represents the energy difference between the products and reactants at constant pressure.

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