Which of the following methods is generally used for the extraction of alkali metals?

$ECG$ depicts the depolarization and repolarization processes during the cardiac cycle. In the $ECG$ of a normal healthy individual,one of the following waves is not represented?

Which one of the following represents the graph between $\log p$ (on $Y$-axis) and $\frac{1}{T}$ (on $X$-axis)?
($p=$ vapour pressure of a liquid,$T=$ absolute temperature)

What is the function of Copper-$T$?

The equation of the radical axis of the pair of circles $7x^2+7y^2-7x+14y+18=0$ and $4x^2+4y^2-7x+8y+20=0$ is

The image of the pair of lines represented by $ax^2 + 2hxy + by^2 = 0$ by the line mirror $y = 0$ is