Which of the following will react with CHCl₃ + alc. KOH?

If the system of equations
x - 2y + 3z = 9
2x + y + z = b
x - 7y + az = 24,
has infinitely many solutions, then a - b is equal to.........

The mean and variance of 8 observations are 10 and 13.5, respectively. If 6 of these observations are 5, 7, 10, 12, 14, 15, then the absolute difference of the remaining two observations is :

Let $$\alpha $$ and $$\beta $$ be the roots of x² - 3x + p=0 and $$\gamma $$ and $$\delta $$ be the roots of x² - 6x + q = 0. If $$\alpha, \beta, \gamma, \delta $$ form a geometric progression.Then ratio (2q + p) : (2q - p) is: