Following four solutions are prepared by mixing different volumes of NaOH and HCl of different concentrations, pH of which one of them will be equal to 1 ?

Biochemical Oxygen Demand (BOD) value can be a measure of water pollution caused by the organic matter. Which of the following statements is correct ?

The number of P $$-$$ O bonds in P₄O₆ is :

In KO₂, the nature of oxygen species and the oxydation state of oxygen atom are, respectively :