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Answer:
1:- Molar mass of ethanol (C
2
H
5
OH) =2(12)+6(1)+16.1=46.1 g/mol
2:- The law of constant proportions states that chemical compounds are made up of elements that are present in a fixed ratio by mass. This implies that any pure sample of a compound, no matter the source, will always consist of the same elements that are present in the same ratio by mass. For example, pure water will always contain hydrogen and oxygen in a fixed mass ratio (a gram of water consists of approximately 0.11 grams of hydrogen and 0.88 grams of oxygen, the ratio is 1:8).
The law of constant proportions is often referred to as Proust’s law or as the law of definite proportions. An illustration describing the mass ratio of elements in a few compounds is provided below. The ratio of the number of atoms of each element is provided below the mass ratio. For example, in a nitrogen dioxide (NO2) molecule, the ratio of the number of nitrogen and oxygen atoms is 1:2 but the mass ratio is 14:32 (or 7:16).
3:- O2 is a molecule consisting of 2 atoms of oxygen. 2O denotes two seperate oxygen atoms. O2 is a molecule and thus it is stable. 2O, whichconsists of 2 different atoms and thus these 2 atoms are ready to combine with any other element like hydrogen.
4:-Calcium Hydroxide has three atoms 5 atoms in each molecule.
One calcium atom
Two oxygen atoms
Two hydrogen atoms
So total 5N
A
atoms are present in N
A
molecules.
5:- ALCL3
6:-Sodium atom has 11 electrons. Sodium ion has 10 electrons as sodium atom loses one electron to form sodium ion. Only sodium atom react vigorously with water whereas sodium ion does not.
7:- The formula unit mass of a substance is the sum of the atomic masses of all the atoms in the formula unit of an ionic compound. = 2Na + 1C + 3O = (2 × 23) + (1 × 12) +( 3 × 16) = 46 + 12 + 48 = 106 u.
Formula mass is defined as the sum of atomic masses of the ions present in the formula unit of an ionic compound while molecular mass is the sum of the atomic masses of the atoms in a molecule
9:-Valency is the combining capacity of the atom of an element. It is equal to the number of electrons an atom can donate or accept or share. Copper and iron shows more than one valency which is also known as variable valency. Therefore, copper shows valencies 1 and 2 : Cu+, cuprous
10:-1 atom of Chlorine weight = 35.453amu
The formula of one molecule of chlorine = Cl2
∴ The molecular mass of Cl2 = 2 × 35.453 amu
The molecular mass of Cl2 = 70.906 amu
we know that
1 amu =1.66×10−24g
The actual molecular mass of chlorine = 70.906×1.66×10−24g
The actual molecular mass of chlorine = 177.7×10−24g.