Two thin circular discs $A$ and $B$ of radii $2 \ cm$ and $4 \ cm$ are in a liquid at the same depth. $T_A$ is the thrust on $A$ and $T_B$ is the thrust on $B$. Then $T_A : T_B =$

The radius of the $Na^{+}$ ion is $95 \ pm$ and that of $Cl^{-}$ ion is $181 \ pm$. Predict the coordination number of $Na^{+}$ in $NaCl$.

When $0.0168 \, mol$ of $O_2$ obtained from the decomposition of $KClO_3$ is collected over water at $25 \, ^\circ C$,the volume is $428 \, mL$ and the pressure is $754 \, mm$. What is the water vapor pressure at $25 \, ^\circ C$ in $mm$?

Which of the following statements is incorrect?

$CH_4$ diffuses two times faster than a gas $X$. The number of molecules present in $32 \ g$ of gas $X$ is ($N$ is Avogadro number).

Equal moles of hydrogen and oxygen gases are placed in a container with a pin-hole through which both can escape. What fraction of the oxygen escapes in the time required for one-half of the hydrogen to escape?