Glucose and mannose are

Which of the following reagents can form a hydrazone with alkanone?

The coefficient of $x^3 y^4 z^5$ in the expansion of $(x y+y z+x z)^6$ is

If the sum of two unit vectors is a unit vector,what is the magnitude of their difference?

$A$ point moves with uniform acceleration and $v_1, v_2$ and $v_3$ denote the average velocities in the three successive intervals of time $t_1, t_2$ and $t_3$. Which of the following relations is correct?

$Ge$ and $Si$ diodes conduct at $0.3\,V$ and $0.7\,V$ respectively. In the following figure,if the $Ge$ diode connection is reversed,the value of $V_0$ changes by.....$V$.