$A$ solid has a structure in which $W$ atoms are located at the corners of a cubic lattice,$O$ atoms at the centre of edges,and $Na$ atoms at the centre of the cube. The formula for the compound is

Chlorine atom,in its third excited state,reacts with fluorine to form a compound $X$. The formula and shape of $X$ are :

The vapour pressure of a solvent decreases by $10 \ mm$ of mercury when a non-volatile solute is added to the solvent. The mole fraction of the solute in the solution is $0.2$. What should be the mole fraction of the solute if the decrease in the vapour pressure is to be $20 \ mm$ of mercury?

$A$ feasible solution to an $LP$ problem,

The flux linked with a coil at any instant $t$ is given by $\phi = 10t^2 - 50t + 250$. The induced emf at $t = 3 \ s$ is ....... $V$.

In a meter bridge,the null point is found at a distance of $25\, cm$ from $A$. If now a resistance of $10\,\Omega$ is connected in parallel with $S$,the null point occurs at the midpoint of $AB$. The value of $R$ is .............. $\Omega$. (in $.67$)