Question

Ребят,помогите решить тест 8. Какова молярная масса HNO3 , равна (г\моль) А) 112 Б) 98 В) 63 Г) 100 9. Что такое валентность: А) валентность элемента – это способность его атома присоединять молекулы другого вещества Б) валентность элемента – это способность его атома присоединять определенное число атомов другого элемента В) валентность элемента – это способность его атома присоединять атомы других элементов Г) валентность элемента – это способность его атомов отдавать свои атомы другим элементам 10. Закон сохранения массы веществ открыл: А) Д.И. Менделеев Б) М.В. Ломоносов В) Дж. Дальтон Г) А. Авогадро 11. Типы химических реакций: А) разложения, соединения, замещения, обмена Б) обмена, соединения, цепные В) ядерные, разложения, соединения, обмена Г) замещение, ядерные, цепные 12. Соединение элемента с кислородом называется: А) сульфидом Б) оксидом В) нитридом Г) бромидом

Answer 1

8. HNO3=1+14+(16×3)=63г/моль

Answer 2

Molar Mass of HNO3

The molar mass of HNO3 can be calculated by adding up the atomic masses of its constituent elements. HNO3 consists of one hydrogen (H) atom, one nitrogen (N) atom, and three oxygen (O) atoms. The atomic masses of these elements are approximately 1 g/mol for hydrogen, 14 g/mol for nitrogen, and 16 g/mol for oxygen.

To calculate the molar mass of HNO3: - Multiply the atomic mass of hydrogen by the number of hydrogen atoms in HNO3 (which is 1). - Multiply the atomic mass of nitrogen by the number of nitrogen atoms in HNO3 (which is 1). - Multiply the atomic mass of oxygen by the number of oxygen atoms in HNO3 (which is 3). - Add up the results of these calculations.

Using the atomic masses mentioned above, the molar mass of HNO3 is calculated as follows: (1 * 1 g/mol) + (1 * 14 g/mol) + (3 * 16 g/mol) = 1 g/mol + 14 g/mol + 48 g/mol = 63 g/mol.

Therefore, the molar mass of HNO3 is 63 g/mol. [[1]]

Valency

Valency refers to the combining capacity of an atom of an element. It represents the number of electrons an atom can gain, lose, or share when it forms chemical bonds with other atoms.

Option B states that the valency of an element is the ability of its atom to combine with a specific number of atoms of another element. This definition accurately describes valency.

Therefore, the correct definition of valency is the ability of an element's atom to combine with a specific number of atoms of another element. [[2]]

Discoverer of the Law of Conservation of Mass

The Law of Conservation of Mass states that in a chemical reaction, the total mass of the reactants is equal to the total mass of the products. This law was discovered by Antoine Lavoisier, a French chemist, in the late 18th century.

Therefore, the correct answer to the question about the discoverer of the Law of Conservation of Mass is C) Antoine Lavoisier. [[3]]

Types of Chemical Reactions

Chemical reactions can be classified into several types based on the changes that occur during the reaction. The most common types of chemical reactions are: - Decomposition reactions: A single compound breaks down into two or more simpler substances. - Combination reactions: Two or more substances combine to form a single compound. - Displacement reactions: An element displaces another element in a compound, resulting in the formation of a new compound. - Redox reactions: These reactions involve the transfer of electrons between reactants. - Acid-base reactions: These reactions involve the transfer of protons (H+ ions) between reactants.

Option A correctly lists the types of chemical reactions as decomposition, combination, displacement, and redox reactions. [[4]]

Compound of an Element with Oxygen

When an element combines with oxygen, the resulting compound is called an oxide. Oxides can have different prefixes depending on the element involved. For example: - A compound of an element with oxygen is called an oxide. - A compound of sulfur with oxygen is called a sulfide. - A compound of nitrogen with oxygen is called a nitride. - A compound of bromine with oxygen is called a bromide.

Therefore, the correct term for a compound of an element with oxygen is B) oxide. [[5]]