Which of the following tests cannot be used for identifying amino acids?

In the reaction of oxalate with permanganate in acidic medium, the number of electrons involved in producing one molecule of CO₂ is :

If  $$\int\limits_0^x \, $$f(t) dt = x² + $$\int\limits_x^1 \, $$ t²f(t) dt then f '$$\left( {{1 \over 2}} \right)$$ is -

Let f be a differentiable function such that f '(x) = 7 - $${3 \over 4}{{f\left( x \right)} \over x},$$ (x > 0) and f(1) $$ \ne $$ 4. Then $$\mathop {\lim }\limits_{x \to 0'} \,$$ xf$$\left( {{1 \over x}} \right)$$ :