10-minute Quiz : Chapter 12 Reacting masses

How many carbon atoms does 11.5 g of ethanol (C₂H₅OH) contain?

(Relative atomic masses: H = 1.0, C = 12.0, O = 16.0; Avogadro constant = 6.02 × 10²³ mol⁻¹)

• A. 1.51 × 10²³

• B. 3.01 × 10²³

• C. 6.02 × 10²³

• D. 1.20 × 10²⁴

If 6.0 g of nitrogen monoxide (NO) contains n molecules, how many molecules does 3.0 g of nitrogen (N₂) contain?

(Relative atomic masses: N = 14.0, O = 16.0)

• A. 0.021n

• B. 0.20n

• C. 0.30n

• D. 0.55n

How many moles of sulphur dioxide contain y oxygen atoms?

(L represents the Avogadro constant.)

• A. y/L

• B. L/y

• C. y/2L

• D. 2y/L

Assume that the total volume of 20 drops of bromine is 1.0 cm³, what is the number of molecules in 1 drop of bromine?

(Avogadro constant = 6.02 × 10²³ mol⁻¹; density of bromine = 3.12 g cm⁻³; relative atomic mass: Br = 79.9)

The relative atomic mass of element Y is 31.0. It forms an oxide containing 56.3% of oxygen by mass, what is the empirical formula of this oxide?

(Relative atomic mass: O = 16.0)

• A. YO₂

• B. YO₃

• C. Y₂O₃

• D. Y₂O₅

Metal M can form a simple ion with a charge of +2. Complete reduction of 50.22 g of this oxide by hydrogen produces metal M and 4.05 g of water. What is the relative atomic mass of M?

(Relative atomic mass: O = 16.0)

• A. 63.5

• B. 158.7

• C. 207.2

• D. 221.2

Consider the following reaction:

H₂O₂(aq) + 2I⁻(aq) + 2H⁺(aq) → I₂(aq) + 2H₂O(l)

In the reaction, the number of I₂ molecules formed is equal to

• A. twice the number of I⁻ ions consumed.

• B. half of the number of H₂O₂ molecules consumed.

• C. half of the number of H⁺ ions consumed.

• D. twice the number of H₂O molecules produced.

What is the mass of sodium chloride that can be produced from the reaction between 18.0 g of sodium and 23.0 g of chlorine?

2Na(s) + Cl₂(g) → 2NaCl(s)

(Relative atomic masses: Na = 23.0, Cl = 35.5)

• A. 19.0 g

• B. 29.7 g

• C. 37.9 g

• D. 45.8 g