What type of life cycle in plants is indicated by the given figure?

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 $A$?

An organ pipe $P_1$ closed at one end is vibrating in its first overtone. Another pipe $P_2$ open at both ends is vibrating in its third overtone. They are in resonance with a given tuning fork. The ratio of the length of $P_1$ to that of $P_2$ is

If $\frac{d^2y}{dx^2} = 0$,then

$A$ string is stretched between fixed points separated by $75.0 \ cm$. It is observed to have resonant frequencies of $420 \ Hz$ and $315 \ Hz$. There are no other resonant frequencies between these two. Then,the lowest resonant frequency for this string is .... $Hz$.

Let $S$ be the sample space of the random experiment of throwing simultaneously two unbiased dice with six faces (numbered $1$ to $6$) and let $E_k = \{(a, b) \in S : ab = k\}$ for $k \geq 1$. If $p_k = P(E_k)$ for $k \geq 1$, then which of the following is correct?