STD 8_sem Ii_chapter 2

Explanation
The correct answer is "પરમાણું". This is because a "પરમાણું" or an atom is the fundamental building block of matter. It is the smallest unit of an element that retains the chemical properties of that element. Atoms combine to form molecules and compounds, which then make up all the substances we see around us. Therefore, the atom is considered the basic component of matter.

Explanation
Electrons are not present in the atomic nucleus. They are found outside the nucleus in the electron cloud. Protons and neutrons are the particles that are present in the atomic nucleus. Therefore, the correct answer is "Electron".

Explanation
The electronic configuration of sodium is 2,8,1. This means that sodium has 11 electrons in total, with 2 electrons in the first energy level, 8 electrons in the second energy level, and 1 electron in the third energy level. The electronic configuration represents the arrangement of electrons in the different energy levels or shells around the nucleus of an atom. In the case of sodium, the first energy level can hold a maximum of 2 electrons, the second energy level can hold a maximum of 8 electrons, and the third energy level can hold a maximum of 8 electrons. Therefore, the correct electronic configuration for sodium is 2,8,1.

Explanation
The correct answer is "અણુ" (Atom). In the given options, "અણુ" is the only term that refers to an individual unit or particle. The other options, "પરમાણુ" (Element), "આયન" (Ion), and "સંયોજન" (Compound), refer to larger entities composed of multiple atoms. Therefore, "અણુ" is the correct answer as it represents the smallest unit of a chemical element.

Explanation
The correct answer is NaCl because NaCl is the chemical formula for common table salt, which is a compound made up of sodium (Na) and chlorine (Cl) ions. The other options, Na2Cl, NaNO2, and MgCl2, do not represent a known compound or do not match the given chemical formula.