The equation of the directrix of the parabola ${y^2} + 4y + 4x + 2 = 0$ is

The coefficient of performance of a refrigerator is $5$. If the temperature inside the freezer is $-20\,^{\circ}C$,the temperature of the surroundings to which it rejects heat is ....... $^{\circ}C$.

Who proposed the binomial nomenclature system?

Viruses are distinct from other living cells because -

$\frac{1}{1 \cdot 3} + \frac{1}{2 \cdot 5} + \frac{1}{3 \cdot 7} + \frac{1}{4 \cdot 9} + \ldots$ is equal to

The locus of a point $P(\alpha, \beta)$ moving under the condition that the line $y = \alpha x + \beta$ is a tangent to the hyperbola $\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1$ is