Questions

Explanations

31 Which electron configuration represents the electrons in an atom of calcium in an excited state?

(1) 2–8–8             (3) 2–7–8–1

(2) 2–8–8–2        (4) 2–7–8–3

2–7–8–3

32 The table below gives the atomic mass and the abundance of the two naturally occurring isotopes of bromine.

Which numerical setup can be used to calculate the atomic mass of the element bromine?

(1) (78.92 u)(50.69) + (80.92 u)(49.31)

(2) (78.92 u)(49.31) + (80.92 u)(50.69)

(3) (78.92 u)(0.5069) + (80.92 u)(0.4931)

(4) (78.92 u)(0.4931) + (80.92 u)(0.5069)

(mass x percent as a decimal) + (mass x percent as a decimal)

33 Given the formulas of two substances:

These diagrams represent substances that have

(1) the same molecular structure and the same physical properties

(2) the same molecular structure and different physical properties

(3) different molecular structures and the same physical properties

34 What is the chemical formula of titanium(II) oxide?

(1) TiO                   (3) TiO₂

(2) Ti₂O                  (4) Ti₂O₃

Ti= 2+   O= 2-

35 Which equation shows conservation of mass and energy for a reaction at 101.3 kPa and 298 K?

(1) 2H₂(g) + O₂(g) → 2H₂O(g)  + 483.6 kJ

(2) 2H₂(g) + O₂(g) → 2H₂O(ℓ)  + 285.8 kJ

(3) H₂(g) + O₂(g) → H₂O(g)  + 483.6 kJ

(4) H₂(g) + O₂(g) → H₂O(ℓ)  + 285.8 kJ

Delta H is negative...energy goes on the right side