$NH_3 + O_2 \xrightarrow[\Delta]{Pt} A + H_2O;$
$A + O_2 \to B$
$B + O_2 + H_2O \to C$
$A, B$ and $C$ are:

The area (in square units) of the region bounded by $x^2=8y$,$x=4$ and the $X$-axis is:

If $A, B$ and $C$ are any three sets,then $A - (B \cup C)$ is equal to

In the circuit shown,a meter bridge is in its balanced state. The meter bridge wire has a resistance of $0.1 \ \Omega/cm$. Find the value of the unknown resistance $X$ and the current drawn from the battery of negligible internal resistance.

An inductor coil carries a steady-state current of $2.0 \, A$ when connected across an ideal battery of $emf \ 4.0 \, V$. If its inductance is $1.0 \, H$,find the time constant of the circuit in $sec$.

Three rods $AB$,$BC$,and $BD$ made of the same material and having the same cross-section have been joined as shown in the figure. The ends $A$,$C$,and $D$ are held at temperatures of $20^{\circ}C$,$80^{\circ}C$,and $80^{\circ}C$ respectively. If each rod is of the same length,then the temperature at the junction $B$ of the three rods is: (in $^{\circ}C$)