Question

which of the following statements about the molar mass of an element is correct?
the molar mass is always a whole number and has units of amu.
the molar mass is numerically equal to the atomic number.
the molar mass is the mass in grams of 6.022×10²³ atoms of the element.
the molar mass is the mass of one atom of the element in grams.
a(n) ______________ is the standard unit used to represent the chemical quantity of any substance.
mass
mole
molar mass
ml
mole ratios that relate reactants to products can be constructed from the coefficients in a balanced chemical equation.
true
false

Explanation:

First Question (Molar Mass of an Element):

• Option 1: Molar mass has units of g/mol, not amu (amu is for atomic mass of one atom), and it's not always a whole number (due to isotopes). Eliminate.
• Option 2: Molar mass is numerically equal to atomic mass (in g/mol), not atomic number (which is proton count). Eliminate.
• Option 3: By definition, molar mass is the mass of one mole (6.022×10²³ atoms/molecules) of a substance in grams. This matches.
• Option 4: Molar mass is for one mole, not one atom. One atom’s mass in grams is very small (atomic mass in amu converted to grams, e.g., 1 amu ≈ 1.66×10⁻²⁴ g). Eliminate.

• "mass" (units g, kg) measures amount of matter, not chemical quantity. Eliminate.
• "mole" is the SI unit for amount of substance (chemical quantity), representing 6.022×10²³ particles. Correct.
• "Molar mass" is mass per mole (g/mol), not a unit of quantity. Eliminate.
• "mL" is a volume unit (for liquids), not for chemical quantity. Eliminate.

In a balanced chemical equation, coefficients represent moles of reactants and products. For example, in \( 2H_2 + O_2
ightarrow 2H_2O \), the mole ratio of \( H_2 \) to \( O_2 \) is 2:1, from coefficients. So the statement is True.

Answer:

The molar mass is the mass in grams of 6.022×10²³ atoms of the element.

Second Question (Standard Unit for Chemical Quantity):