What is true about the element francium (Fr, atomic number 87)? More than one can be true A) It has seven valence electrons. B) It is likely to form ionic bonds. C) It is in Period 7. D) It is nonmetal. E) It is a metal.
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(2) The proportion by mass of elements combined in potassium chlorate varies.
(3) Potassium chlorate is composed of four elements.
(4) Potassium chlorate is composed of five elements.
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Answer : The correct option is, (1) The proportion by mass of elements combined in potassium chlorate is fixed.
Explanation :
The composition of any compound is studied on the basis of law of fixed proportion. This law stats that in a compound the elements are present in fixed proportion by their mass.
In the given options, the option (1) statement describes the composition of potassium chlorate.
While the other options (2), (3) and (4) statements does not describe the composition of potassium chlorate.
Hence, the correct option is (1).
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Considering the definition of molar mass and molarity, the volume of each compound is:
- NaCl= 0.1355 L
- C₂H₆O = 0.0622 L
- CH₃COOH = 0.047 L
Definition of molar mass
The molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.
Definition of molarity
Molar concentration or molarity is a measure of the concentration of a solute in a solution and indicates the number of moles of solute that are dissolved in a given volume.
The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution:
Molarity is expressed in units.
Volume required
You know that the molar mass of each compound is:
- NaCl = 58.44 g/mol
- C₂H₆O = 46.06 g/mol
- CH₃COOH = 60.0 g/mol
On the other side, you know that the mass of each compound is:
- NaCl = 2.14 g
- C₂H₆O = 4.30 g
- CH₃COOH = 0.85 g
Then, considering the definition of molar mass, the amount of moles of each compound is:
- NaCl =
= 0.0366 moles
- C₂H₆O =
= 0.0933 moles
- CH₃COOH =
= 0.0141 moles
The molarity of each compound is:
- NaCl = 0.27 M
- C₂H₆O = 1.50 M
- CH₃COOH = 0.30 M
Considering the molarity, the volume of each compound is calculated as:
- NaCl =
= 0.1355 L
- C₂H₆O =
= 0.0622 L
- CH₃COOH =
= 0.047 L
Learn more about
molar mass:
molarity:
number of moles : 2.14 / 58.44 = 0.0366 moles
V = n / M => 0.0366 / 0.270 = 0.1355 L
__________________________________________
b) C2H6O = 46.06 g/mol
number of moles : 4.30 / 46.06 = 0.0933 moles
V = n / M => 0.0933 / 1.50 = 0.0622 L
___________________________________________
c) CH3COOH = 60.0 g/mol
number of moles : 0.85 / 60.0= 0.0141 moles
V = n / M => 0.0141 / 0.30 = 0.047 L
___________________________________________
hope this helps!