Which of the following noble gases has the highest polarizability?

The molarity of a $0.2 \ N \ Na_2CO_3$ solution will be .......... $M$.

Which one of the following compounds forms a quaternary salt on reacting with excess methyl iodide?

When is the '$DUB$' sound heard during the cardiac cycle?

Velocity of sound waves in air is $330 \ m/s$. For a particular sound wave in air,a path difference of $40 \ cm$ is equivalent to a phase difference of $1.6 \pi$. The frequency of this wave is: (in $Hz$)

If $3 \hat{i}+3 \hat{j}+\sqrt{3} \hat{k}$, $\hat{i}+\hat{k}$, and $\sqrt{3} \hat{i}+\sqrt{3} \hat{j}+\lambda \hat{k}$ are coplanar, then $\lambda$ is equal to