List of top Chemistry Questions on Half life asked in BITSAT

For a first-order reaction \( A \rightarrow B \), the rate constant is \( 0.1 \text{ s}^{-1} \). What is the time required for \( 50\% \) completion?
The reaction \( A(g) \rightarrow P(g) + Q(g) + R(g) \) follows first-order kinetics with a half-life of \( 69.3 \) s at \( 500^{\circ}\text{C} \). Starting with pure \( A \) in a container at \( 500^{\circ}\text{C} \) and a pressure of \( 0.4 \) atm, what will be the total pressure of the system after \( 230 \) s?
A radioactive sample has a half-life of 10 days. The fraction of the initial nuclei decayed after 40 days is:
Two substances R and S decompose in solution independently, both following first order kinetics. The rate constant of R is twice that of S. Initially 0.5 millimoles of R and 0.25 of S. The molarities of R and S will be equal at the end of time equal to: