Chemical $A$ is used for water softening to remove temporary hardness. $A$ reacts with sodium carbonate to generate caustic soda. When $CO_2$ is bubbled through $A$,it turns cloudy,what is $A$?

$A$ block of $3\,kg$ is initially in equilibrium and is hanging by two identical springs $A$ and $B$ as shown in the figure. If spring $A$ is cut from the lower point at $t=0$,then find the acceleration of the block in $m/s^2$ at $t=0$. (Take $g = 10\,m/s^2$)

Two gaseous equilibria $SO_{2(g)} + \frac{1}{2} O_{2(g)} \rightleftharpoons SO_{3(g)}$ and $2 SO_{3(g)} \rightleftharpoons 2 SO_{2(g)} + O_{2(g)}$ have equilibrium constants $K_{1}$ and $K_{2}$ respectively at $298 \ K$. Which of the following relationships between $K_{1}$ and $K_{2}$ is correct?

If the ionic product of water $(K_w)$ is $1.96 \times 10^{-14}$ at $35^{\circ} C$,what is its value at $10^{\circ} C$?

Which of the following does not act as a neurotransmitter?

Which of the following is a redox reaction?