• # question_answer What is the correct relationship between the pHs of isomolar solutions of sodium oxide $(p{{H}_{1}}),$ sodium sulphide $(p{{H}_{2}}),$ sodium selenide $(p{{H}_{3}})$ and sodium telluride $(p{{H}_{4}})$ [CBSE PMT 2005] A) $p{{H}_{1}}>p{{H}_{2}}=p{{H}_{3}}>p{{H}_{4}}$ B) $p{{H}_{1}}<p{{H}_{2}}<p{{H}_{3}}<p{{H}_{4}}$ C) $p{{H}_{1}}<p{{H}_{2}}<p{{H}_{3}}=p{{H}_{4}}$ D) $p{{H}_{1}}>p{{H}_{2}}>p{{H}_{3}}>p{{H}_{4}}$

Order of acidic strength is ${{H}_{2}}Te>{{H}_{2}}Se>{{H}_{2}}S>{{H}_{2}}O$ $N{{a}_{2}}O$ is a salt of $NaOH+{{H}_{2}}O$and ${{H}_{2}}O$is least acidic among given acids hence pH in this case will be maximum.