AIIMS2008Chemistryp Block Elements (Group 15, 16, 17 & 18)
What is the correct relationship between the ( pH ) of isomolar solutions of sodium oxide ( ( pH ₁ ) ), sodium sulphide ( ( pH ₂ ) ), sodium selenide ( ( pH ₃ ) ) and sodium telluride ( ( pH ₄ ) ) ?
Options
- A( pH ₁> pH ₂= pH ₃= pH ₄ )
- B( pH ₁ < pH ₂ < pH ₃ < pH ₄ )
- C( pH ₁ pH ₃ < pH ₄ )
- D( pH ₁> pH ₂> pH ₃> pH ₄ ).
Correct answer
D. ( pH ₁> pH ₂> pH ₃> pH ₄ ).
Step-by-step solution
array ll I & Na ₂ O + H ₂ O 2 NaOH II & Na ₂ ~S + H ₂ O 2 NaOH + H ₂ ~S III & Na ₂ Se + H ₂ O 2 NaOH + H ₂ Se IV & Na ₂ Te + H ₂ O 2 NaOH + H ₂ Te array I will have the highest pH . Among H ₂ ~S , H ₂ Se , H ₂ Te acidity goes on increasing on going down the group as bond length increases on increasing size of central atom. So, pH ₄ pH ₂> pH ₃> pH ₄