Diamond and emerald are forms of which of the following respectively?

Which of the following statements are correct?
$I)$ $SnF_4$ is ionic in nature.
$II)$ Stability of dihalides of group $14$ elements increases down the group.
$III)$ $GeCl_2$ is more stable than $GeCl_4$.

$A$ red solid is insoluble in water,but it becomes soluble if a small amount of $KI$ is added to the water. If this red solid is heated in a test tube,it produces a violet-colored vapor and some metallic droplets are observed on the cooler parts of the test tube. This red solid is........

Silicon has a strong tendency to form polymers like silicones. The chain length of silicone polymer can be controlled by adding :-

When a colored gas is passed through bromine water,the color is discharged. Which gas is it?

Holme signal can be given by using which of the following mixtures?