Question

$CO^-$ ion moving with kinetic energy of $20\, keV$ dissociates into $O^-$ and $C$ which move along the parent ion direction. Assuming no energy is released during dissociation, the kinetic energy of the daughters $(K.E)_{O^-}$ and $(K.E)_C$ are related as

• A. $(K.E)_{O^-} = (K.E)_C$
• B. $(K.E)_{O^-}/(K.E)_C= 16/12$
• C. $(K.E)_{O^-}/(K.E)_C= 12/16$
• D. $(K.E)_{O^-}/(K.E)_C= 16/28$

Answer 1

Answer: (C)

$(K.E)_{O^-}/(K.E)_C= 12/16$

Answer 2

As no energy is released, lighter particle carries more $K . E$
$\therefore K . E \propto \frac{1}{\text{mass}}$
$\therefore$ Molar mass of carbon $=12$
Molar mass of oxygen $=16$
Thus, they are related as
$\frac{K_{O}}{K_{C}} =\frac{\text { Molar mass of carbon }}{\text { Molar mass of oxygen }}$
$=\frac{12}{16}$