Multiple choice

Which of the following terms statements are correct?

  1. All alkali metal elements form solid hydrogen carbonates.
  2. Calcium is fifth most abundant element in the earth’s crust.
  3. Francium is highly radioactive.
  4. Hydration enthalpies of alkaline earth metal ions are larger than those of alkali metal ions.

  1. 1 and 2

  2. 1 and 4

  3. 2 and 3

  4. 2 and 4

  5. 3 and 4
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Francium is highly radioactive; its longest-lived isotope 223-Fr has a half-life of only 21 minutes. The hydration enthalpies of alkaline earth metal ions are larger than those of alkali metal ions. Thus, compounds of alkaline earth metals are more extensively hydrated than those of alkali metals, e.g. MgCl2 and CaCl2 exist as MgCl2.6H2O and CaCl2• 6H2O while NaCl and KCl do not form such hydrates.

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