What does orthoboric acid contain?

Chloroethane reacts with $X$ to form diethyl ether. What is $X$?

$CH_3-CH_2-CH=O$ $\xrightarrow[(2) H^{+}]{(1) \text{Tollen's reagent}} X$ $\xrightarrow[(2) \text{dry distillation}]{(1) Ca(OH)_2} Y$
$Y$ is:

Celestite is a mineral of which of the following?

$\int (1+x-x^{-1}) e^{x+x^{-1}} dx$ is equal to :

Six moles of an ideal gas perform a cycle shown in the figure. If the temperatures are $T_A = 600 \ K, T_B = 800 \ K, T_C = 2200 \ K$,and $T_D = 1200 \ K$,the work done per cycle is ..... $kJ$.