Which of the following hormones contains iodine?

$A$ thin plano-convex lens of focal length $73.5 \text{ cm}$ has a circular aperture of diameter $8.4 \text{ cm}$. If the refractive index of the material of the lens is $\frac{5}{3}$,then the thickness of the lens is nearly

$A$ semiconductor $X$ is made by doping a germanium crystal with arsenic $(Z=33)$. $A$ second semiconductor $Y$ is made by doping germanium with indium $(Z=49)$. The two are joined end to end and connected to a battery as shown. Which of the following statements is correct?

Which of the following quantities does not depend upon the orbital radius of the satellite?

If $\alpha, \beta$ are the roots of $x^2 - px + q = 0$ and $\alpha', \beta'$ are the roots of $x^2 - p'x + q' = 0$,then find the value of $(\alpha - \alpha')^2 + (\beta - \alpha')^2 + (\alpha - \beta')^2 + (\beta - \beta')^2$.

What happens when:
$(a)$ Borax is heated strongly,
$(b)$ Boric acid is added to water,
$(c)$ Aluminium is treated with dilute $NaOH$,
$(d)$ $BF_3$ is reacted with ammonia?