$A$ sound absorber attenuates the sound level by $20\, dB$. The intensity decreases by a factor of:

Which science presents the changes in the internal and external structure of plants from the perspective of evolution and phylogeny?

Which of the following statements is incorrect?

$\sin 120^{\circ} \cos 150^{\circ} - \cos 240^{\circ} \sin 330^{\circ}$ is equal to :

Efficiency of a heat engine whose sink is at a temperature of $300 ~K$ is $40 \%$. To increase the efficiency to $60 \%$,keeping the sink temperature constant,the source temperature must be increased by (in $~K$)

An integrating factor of the differential equation $(1-x^2) \frac{dy}{dx} + xy = \frac{x^4}{(1+x^5)} (\sqrt{1-x^2})^3$ is