The gas which turns lime water milky is

Identify the incorrect statement about $SiO_2$ (silica) from the following.

Which of the following oxides is amphoteric in character?

Which of the following statements are correct?
$(a)$ The isotope of carbon containing $7$ neutrons has natural abundance of $1.1 \%$.
$(b)$ Among the $IV$ $A$ group elements,$Sn$ has the lowest melting point.
$(c)$ Silicon is the $2^{nd}$ (by mass) most abundant element in the earth's crust.
$(d)$ Elemental carbon shows the highest electrical resistivity among the $14$ group elements.

Which of the following is not correct?

For bleaching powder,which of the following statements is incorrect?