Practice question

Given: A neutron ( 1 u ) moving at 2 × 10⁶ m/s collides elastically with a carbon nucleus ( 12 u ). What fraction of its kinetic energy is retained? These values define the system as per NCERT data. Formula: Fraction retained f_1 = ( m_1 - m_2/m_1 + m_2 )² = ( 1 - 12/1 + 12 )² = ( -11/13 )² = 121/169 approx 0.716 .. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Substituting values like 1.2 × 10⁻⁵, 236 J kg⁻¹ K⁻¹, CH₃CH₂NH₂ etc. into the formula and simplifying step by step. Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.