Let $f(x) = x^3 + bx^2 + cx + d$ where $0 < b^2 < c$. Then $f(x)$:

The angle between the lines $2x = 3y = -z$ and $6x = -y = -4z$ is ......... $^o$.

$A$ certain metal is used in the preparation of antacids. This metal accidentally catches fire and cannot be extinguished using $CO_2$. Which metal is this?

In a co-axial,straight cable,the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero:

Which of the following statements is incorrect for $Nostoc$ and $Anabaena$?

The circumference of a circle is measured as $56 \text{ cm}$ with an error of $0.02 \text{ cm}$. The percentage error in its area is