Which of the following is $NOT$ a polymorphic form of silica $(SiO_2)$?

Among the following options, the element with the highest density and lowest boiling point is

Superphosphate of lime contains

$(1)$ Half-life of $^{14}C$ is $...........$
$(2)$ $..........$ isotope of carbon is used in radiocarbon dating.
$(3)$ Main component of ceramic,cement and glass is $........$

What is/are true about $CO_2$ and $SO_2$?

In the carbon family,elements other than carbon do not form $p\pi - p\pi$ bonds because their atomic radii are very ........