Which of the following compounds lacks iron?

The coefficient of $x$ in the equation $x^2 + px + q = 0$ was taken as $17$ in place of $13$. Its roots were found to be $-2$ and $-15$. The roots of the original equation are:

Which of the following oxides cannot act as a reducing agent?

If the sum of the roots of the equation $x^2 + px + q = 0$ is three times their difference,then which of the following is true?

Bamboo and grasses elongate by the activity of ......

If the line $lx + my = 1$ is a normal to the hyperbola $\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1$,then $\frac{a^2}{l^2} - \frac{b^2}{m^2}$ is equal to