First classification of elements and natural families
Answers are for parents and teachers.
1
Name the two kinds of reactions that show aluminium hydroxide is amphoteric.
With an acid (HCl) it forms AlCl₃ and water; with an alkali (NaOH) it forms an aluminate and water.
2
Write the equation of potassium with water.
2K + 2H₂O → 2KOH + H₂↑
3
Write the formulas of the oxides of Rb and Cs.
Rb₂O and Cs₂O
4
How many mol of KOH form when 78 g of potassium (Aᵣ = 39) react with water?
2
5
Why are sodium and potassium kept under kerosene? (Only a teacher handles them.)
They react quickly with oxygen and moisture of air; kerosene separates them from air.