Properties of Common Inorganic Substances

How the real exam tests it

Questions from real CSCA papers that test this concept. Work each one out before you open the answer.

1. CSCA Chemistry April 2026 Past Paper
   Given the reaction $\mathrm{Cl_{2}}$ + 2NaOH = NaCl + Y + $\mathrm{H_{2}O}$, the molecular formula of Y is ( ).
   • A. HCl
   • B. NaClO
   • C. HClO
   • D. $\mathrm{NaClO_{3}}$
   Show answer & solution

   Answer: B

   Answer: B Balancing by conservation of atoms: $\mathrm{Cl_{2}}$ + 2NaOH = NaCl + NaClO + $\mathrm{H_{2}O}$, so Y is NaClO.
   Take the full CSCA Chemistry April 2026 Past Paper — timed & graded
2. CSCA Chemistry March 2026 Past Paper
   Concentrated sulfuric acid left open - which is correct?
   • A．Solution mass decreases
   • B．Solute mass fraction decreases
   • C．Solvent mass unchanged
   • D．Solution pH decreases
   Show answer & solution

   Answer: B

   Conc. $\mathrm { H } _ { 2 } \mathrm { SO } _ { 4 }$ absorbs moisture → mass increases → mass fraction decreases. Answer: B.
   Take the full CSCA Chemistry March 2026 Past Paper — timed & graded