The half-life of a radioactive substance is 12 min . The time gap between $28 \%$ decay and $82 \%$ decay of the radioactive substance is

An element consists of a mixture of three isotopes $A, B$ and $C$ of masses $m_1, m_2$ and $m_3$, respectively. If the relative abundances of the three isotopes $A, B$ and $C$ are in the ratio $2: 3: 5$, the average mass of the element is

The concentration of electrons in an intrinsic semiconductor is $6 \times 10^{15} \mathrm{~m}^{-3}$. On doping with an impurity, the electron concentration increases to $4 \times 10^{22} \mathrm{~m}^{-3}$. In thermal equilibrium, the concentration of the holes in the doped semiconductor is

Three logic gates are connected as shown in the figure. If the inputs are $A=1$ and $B=1$, then the values of $Y_1$ and $Y_2$ respectively are