Acidified potassium permanganate solution is decolourised by

When $KMnO_4$ solution is added to hot oxalic acid solution,the decolourisation is slow in the beginning but becomes instantaneous after some time. This is because

Why are some genetic disorders not eliminated from the gene pool despite being harmful?

If the $B-H$ curves of two samples of $P$ and $Q$ of iron are as shown below, then which one of the following statements is $CORRECT$?

The expression $[(p \wedge \sim q) \vee q] \vee (\sim p \wedge q)$ is equivalent to

In a series of $2n$ observations,half of the observations are equal to $a$ and the remaining are equal to $-a$. If the standard deviation of the observations is $2$,then what is the value of $|a|$?