Three numbers are chosen at random from $1$ to $20$. The probability that they are consecutive is

The focal length of a mirror is given by $\frac{2}{f} = \frac{1}{v} - \frac{1}{u}$. In finding the values of $u$ and $v$,the errors are equal to $p$. Then,the relative error in $f$ is

The quadratic equation whose roots are $\sin ^2 18^{\circ}$ and $\cos ^2 36^{\circ}$ is :

Which of the following substances is known as lead sugar?

The function $f: R \rightarrow R$ is defined by $f(x) = \cos^2 x + \sin^4 x$ for $x \in R$. Then the range $f(R)$ is equal to

For the reaction $3X_{(g)} + Y_{(g)} \rightleftharpoons X_3Y_{(g)}$,the amount of $X_3Y$ at equilibrium is affected by ...........