What are plasmodesmata?

$e^{\log (\cosh^{-1} 2)}$ is equal to :

What does the given diagram of enzyme action represent?

The image of the pair of lines represented by $ax^2 + 2hxy + by^2 = 0$ by the line mirror $y = 0$ is

The major product of the following reaction is

The efficiency of a Carnot engine is $50\%$ and the temperature of the sink is $500\, K$. If the temperature of the source is kept constant and its efficiency is to be raised to $60\%$,then the required temperature of the sink will be........ $K$.