The statement $$ \sim \left( {p \leftrightarrow \sim q} \right)$$ is :

The variance of first 50 even natural numbers is

A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it?

From a tower of height H, a particle is thrown vertically upwards with a speed u. The time taken by the particle, to hit the ground, is n times that taken by it to reach the highest point of its path. The relation between H, u and n is: