Questions

Explanations

26 Which compound is an electrolyte?

(1) H₂O (3) H₃PO₄

(2) C₂H₆ (4) CH₃OH

27 When the hydronium ion concentration of an aqueous solution is increased by a factor of 10, the pH value of the solution

(1) decreases by 1     (3) decreases by 10

(2) increases by 1      (4) increases by 10

28 The stability of isotopes is related to the ratio of which particles in the atoms?

(1) electrons and protons

(2) electrons and positrons

(3) neutrons and protons

(4) neutrons and positrons

29 Which radioisotope has the fastest rate of decay?

(1) ¹⁴C (3) ⁵³Fe

(2) ³⁷Ca (4) ⁴²K

30 The atomic mass of an element is the weighted average of the atomic masses of

(1) the least abundant isotopes of the element

(2) the naturally occurring isotopes of the element

(3) the artificially produced isotopes of the element

(4) the natural and artificial isotopes of the element