paper 1 past exam questions

• Which calcium compound contains the greatest percentage by mass of calcium?

  calcium hydroxide
• Which pair of solutions forms a white precipitate?

  Cr2(SO4)3(aq) and BaCl2(aq)
• Aqueous Cr3+ ions are reacted with an excess of aqueous sodium hydroxide. Which product is formed

  Cr(OH)6$^{3-}$
• NH4 +

  • tetrahedral and 109.5
• NH2 –

  • angular
  • 104.5
• Explain why the boiling point of PH3 is lower than the boiling point of NH3.

  • NH3 has hydrogen bonding
  • hydrogen bonding is stronger
  • PH3 does not have hydrogen bonding
• Explain why the boiling point of PH3 is lower than the boiling point of AsH3.

  • AsH3 has more electrons
  • in AsH3 there are more induced dipole-dipole interactions
• The reactivity of the Group 2 elements Mg–Ba increases down the group. Explain why

  • nuclear attraction decreases
  • more shielding
  • less energy needed to remove electrons (ionisation energy decreases)
• What is the systematic name for KClO4?

  • potassium chlorate (VII)
• Why is equilibrium 18.1 a heterogeneous equilibrium?

  • species have different states
• Standard conditions for cell potential

  • 1 mol dm-3
  • 298K