The number of optical isomers in following compound is : __________.

Number of carbocations from the following that are not stabilized by hyperconjugation is _______.

Using the given figure, the ratio of $$\mathrm{R}_f$$ values of sample $$\mathrm{A}$$ and sample $$\mathrm{C}$$ is $$x \times 10^{-2}$$. Value of $$x$$ is __________.

The total number of 'sigma' and 'pi' bonds in 2-oxohex-4-ynoic acid is ______.