$A$ particle is moving in a circle with uniform speed $v$. In moving from a point to another diametrically opposite point:

Despite being multicellular,its cells are not organized into tissues.

If the position vectors of $A, B$ and $C$ are respectively $2 \hat{i}-\hat{j}+\hat{k}, \hat{i}-3 \hat{j}-5 \hat{k}$ and $3 \hat{i}-4 \hat{j}-4 \hat{k}$, then $\cos ^2 A$ is equal to

Charges are placed on the vertices of a square as shown. Let $\overrightarrow{E}$ be the electric field and $V$ be the electric potential at the centre. If the charges on $A$ and $B$ are interchanged with those on $D$ and $C$ respectively,then:

The cathode of a photoelectric cell is changed such that the work function changes from $W_1$ to $W_2$ $(W_2 > W_1)$. If the current before and after the change are $I_1$ and $I_2$ respectively,with all other conditions remaining unchanged,then (assuming $h\nu > W_2$):

Sodium is heated in air at $300^{\circ} C$ to form $X$. $X$ absorbs $CO_2$ and forms $Na_2CO_3$ and $Y$. Which of the following is $Y$?