The radioisotope, tritium 13(H) has a half-life of 12.3 years. If the initial amount of tritium is 32 mg, how many milligrams of it would remain after 49.2 years:

The oxidation states of sulphur in the anions SO₃^2–, S₂O₄^2– and S₂O₆^2– follow the order-

The correct order of reactivity towards the electrophilic substitution of the compounds aniline (I), benzene (II) and nitrobenzene (III) is

The densities of graphite and diamond at $298\, K$ are $2.25$ and $3.31\, g\, cm^{-3},$ respectively. If the standard free energy difference $(\Delta G^{\circ})$ is equal to $1895\, J\, mol^{-1}$, the pressure at which graphite will be transformed into diamond at $298\, K$ is -

What is the entropy change (in $JK^1\, mol^1$) when one mole of ice is converted into water at $0^{\circ}C$ ?(The enthalpy change for the conversion of ice to liquid water is $6.0 \, kJ \, mol^{-1}$ at $0^{\circ}C$)

The correct order of ionic radii of $Y ^{3+}, La ^{3+}$ $Eu ^{3+}$, and $Lu ^{3+}$ is : - Atomic nos. $Y =39,\, La =57,\, Eu =63,\, Lu =71$.

The basic character of the transition metal monoxides follows the order: (Atomic no. - Ti = 22, V = 23, Cr = 24, Fe = 26)

The method of zone refining of metals is based on the principle of :

In this reaction, $CH _{3} CHO + HCN \rightarrow CH _{3} CH ( OH ) CN$ $\stackrel{\text { H.OH }}{\longrightarrow} CH _{3} CH ( OH ) COOH$ an asymmetric centre is generated. The acid obtained would be

Identify the electronic configuration of transition element.

The ions $O_2^–$, $F^–$, $Na^+$, $Mg^{2+}$ and $Al^{3+}$ are isoelectronic. Their ionic radii show: