Carbon,silicon,and germanium have four valence electrons each. These are characterized by valence and conduction bands separated by energy band gaps equal to $(E_{g})_{C}$,$(E_{g})_{Si}$,and $(E_{g})_{Ge}$ respectively. Which of the following statements is true?

Which of the following reactions is $NOT$ associated with the Solvay process for the manufacture of sodium carbonate?

$A$ diatomic ideal gas is used in a Carnot engine as the working substance. If during the adiabatic expansion part of the cycle the volume of the gas increases from $V$ to $32V$,the efficiency of the engine is

At $300 K$ , an ideal dilute solution of a macromolecule exerts osmotic pressure that is expressed in terms of the height $(h)$ of the solution $($density $=1.00 g cm ^{-3} )$ where h is equal to $2.00 cm$ . If the concentration of the dilute solution of the macromolecule is $2.00 g dm ^{-3}$, the molar mass of the macromolecule is calculated to be $X \times 10^4 g mol ^{-1}$. The value of $X$ is $...$ .
Use : Universal gas constant $(R)=8.3 J K ^{-1} mol^{-1}$ and acceleration due to gravity $( g )=10 m s ^{-2}$

Let $PQ$ and $RS$ be tangents at the extremities of the diameter $PR$ of a circle of radius $r$. If $PS$ and $RQ$ intersect at a point $X$ on the circumference of the circle,then $2r$ equals

Beryllium is placed above magnesium in Group $2$. What happens when beryllium powder is added to a solution of $MgCl_2$?