If standard reduction potential of four electrodes A, B, C, D are $+2.5\,\text{V}, +3.0\,\text{V}, -2.0\,\text{V}$ and $-1.5\,\text{V}$ respectively. When is the standard emf of cell maximum?

Which of the following is an example of fractional order reaction ?

What is the time required for 75 % completion of a first order reaction if rate constant is $23.03\ \text{minute}^{-1}$ ?

For a reaction $\text{A} \longrightarrow$ product, $k = 2 \times 10^{-2}\ \text{s}^{-1}$. If the initial concentration of A is $1.0\ \text{mol dm}^{-3}$ find the value of $\log \dfrac{1}{[A]_t}$ after 100 second ?