A gaseous hydrocarbon gives upon combustion 0.72 g of water and 3.08 g of CO₂. The empirical formula of the hydrocarbon is

Consider the following reaction:

$$xMnO_4^- + yC_2O_4^{2-}$$ + zH⁺ $$\to$$ xMn²⁺ + 2yCO₂ + $${z \over 2}{H_2}O$$

The value's of x, y and z in the reaction are, respectively :

Let A and B be two sets containing 2 elements and 4 elements respectively. The number of subsets of A $$ \times $$ B having 3 or more elements is :

All the students of a class performed poorly in Mathematics. The teacher decided to give grace marks of 10 to each of the students. Which of the following statistical measures will not change even after the grace marks were given?