When is the immune response most intense?

In the following common emitter circuit,if $\beta = 100$,$V_{CE} = 7 \, V$,$V_{BE} = \text{Negligible}$,and $R_C = 2 \, k\Omega$,then find $I_B$ in $mA$.

What are $\underline{A}, \underline{B}, \underline{C}$ in the following reactions?
$(I)$ $(CH_3 CO_2)_2 Ca \xrightarrow{\Delta} \underline{A}$
$(II)$ $CH_3 CO_2 H \xrightarrow[Red\ P]{HI} \underline{B}$
$(III)$ $2 CH_3 CO_2 H \xrightarrow{P_4 O_{10}} \underline{C}$
$\underline{A} \quad \underline{B} \quad \underline{C}$

In an experiment on photoelectric emission from a metallic surface,the wavelength of incident light is $2 \times 10^{-7} \ m$ and the stopping potential is $2.5 \ V$. The threshold frequency of the metal (in $Hz$) is approximately (charge of electron $e = 1.6 \times 10^{-19} \ C$,Planck's constant $h = 6.6 \times 10^{-34} \ J \cdot s$):

Match the following genes of the $Lac$ operon with their respective products:
List-$I$ (Gene) | List-$II$ (Product)
$(i)$ $i$ gene | $(1)$ $\beta$-galactosidase
$(ii)$ $z$ gene | $(2)$ Permease
$(iii)$ $y$ gene | $(3)$ Repressor
$(iv)$ $a$ gene | $(4)$ Transacetylase
Select the correct option.

The coefficient of $x^{10}$ in the expansion of $(2+3x)e^{-x}$ is