Degeneration of the corpus luteum causes

Starting with a sample of pure $^{66}Cu$,$\frac{7}{8}$ of it decays into $Zn$ in $15 \ min$. The corresponding half-life is .......... $min$.

Which of the following is/are barbiturates?

$A$ codon has a sequence of $\underline{A}$,and specifies a particular $\underline{B}$ that is to be incorporated into a $\underline{C}$. What are $\underline{A}, \underline{B}, \underline{C}$ ?
$\underline{A} \quad \underline{B} \quad \underline{C}$

$A$ clock $S$ is based on the oscillation of a spring,and a clock $P$ is based on pendulum motion. Both clocks run at the same rate on Earth. On a planet having the same density as Earth but twice the radius,which of the following is true?

In the Fraunhofer diffraction experiment,$L$ is the distance between the screen and the obstacle,$b$ is the size of the obstacle,and $\lambda$ is the wavelength of the incident light. The general condition for the applicability of Fraunhofer diffraction is: