For kinetic study of the reaction of iodide ion with $$\mathrm{H}_{2} \mathrm{O}_{2}$$ at room temperature :

(A) Always use freshly prepared starch solution.

(B) Always keep the concentration of sodium thiosulphate solution less than that of KI solution.

(C) Record the time immediately after the appearance of blue colour.

(D) Record the time immediately before the appearance of blue colour.

(E) Always keep the concentration of sodium thiosulphate solution more than that of KI solution.

Choose the correct answer from the options given below :

In the given reaction,

$$X+Y+3 Z \leftrightarrows X YZ_{3}$$

if one mole of each of $$X$$ and $$Y$$ with $$0.05 \mathrm{~mol}$$ of $$Z$$ gives compound $$X Y Z_{3}$$. (Given : Atomic masses of $$X, Y$$ and $$Z$$ are 10, 20 and 30 amu, respectively.) The yield of $$X YZ_{3}$$ is _____________ g. (Nearest integer)

An element M crystallises in a body centred cubic unit cell with a cell edge of $$300 \,\mathrm{pm}$$. The density of the element is $$6.0 \mathrm{~g} \mathrm{~cm}^{-3}$$. The number of atoms present in $$180 \mathrm{~g}$$ of the element is ____________ $$\times 10^{23}$$. (Nearest integer)

The number of paramagnetic species among the following is ___________.

$$\mathrm{B}_{2}, \mathrm{Li}_{2}, \mathrm{C}_{2}, \mathrm{C}_{2}^{-}, \mathrm{O}_{2}^{2-}, \mathrm{O}_{2}^{+}$$ and $$\mathrm{He}_{2}^{+}$$