Which of the following alkenes does $NOT$ exhibit cis-trans isomerism?

If the lines $x^2+2xy-35y^2-4x+44y-12=0$ and $5x+\lambda y-8=0$ are concurrent,then the value of $\lambda$ is

${\left( -\frac{1}{2} + \frac{\sqrt{3}}{2}i \right)^{1000}} = .....$

Two of the lines represented by the equation $a y^4+b x y^3+c x^2 y^2+d x^3 y+e x^4=0$ will be perpendicular,then

An auditorium has a volume of $10^5 \ m^3$ and a total absorption area of $2 \times 10^4 \ m^2$. Its average absorption coefficient is $0.2$. The reverberation time of the auditorium in seconds is:

Which of the following would produce a buffer solution when mixed in equal volumes?