Ribose is an example of

Which of the following crops produces recalcitrant seeds?

The correct sequence of plants in a hydrosere is

If the centroid of the triangle formed by the lines $2y^2 + 5xy - 3x^2 = 0$ and $x + y = k$ is $\left(\frac{1}{18}, \frac{11}{18}\right)$,then the value of $k$ equals $............$

The half-life period of a radioactive element $X$ is the same as the mean lifetime of another radioactive element $Y$. Initially, both of them have the same number of atoms. Then:

Assertion : $HClO_4$ is a stronger acid than $HClO_3$.
Reason : Oxidation state of $Cl$ in $HClO_4$ is $+7$ and in $HClO_3$,it is $+5$.