Lead oxide (PbO) can be dissolved in

Among the following, the number of halide(s) which is/ are inert to hydrolysis is

(A) ${\mathrm{BF}}_3$
(B) ${\mathrm{SiCl}}_4$
(C) ${\mathrm{PCl}}_5$
(D) ${\mathrm{SF}}_6$

Two elements $\mathrm{A}$ and $\mathrm{B}$ have electronegativities $1.2$ and $3.0$ respectively. The nature of bond between $\mathrm{A}$ and $\mathrm{B}$ would be

The setting time of Cement is increased by adding

What should be the correct order of lattice energy values of the following alkali halides?

$\mathrm{LiCl},\mathrm{KI},\mathrm{KCl}$and $\mathrm{NaCl}$

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R

Assertion A :- Carbon forms two important oxides $\mathrm{CO}$ and ${\mathrm{CO}}_2$. $\mathrm{CO}$ is neutral whereas ${\mathrm{CO}}_2$ is acidic in nature.

Reason R :  ${\mathrm{CO}}_2$ can combine with water in a limited way to form carbonic acid, while $\mathrm{CO}$ is sparingly soluble in water.

In the light of the above statements, choose the most appropriate answer from the options given below :-

Identify the correct statements from the following.

i) Quartz is a piezoelectric material
ii) All group $14$ tetrachlorides except ${\mathrm{CCl}}_4$ are easily hydrolyzed in water.
iii) The $\mathrm{C}-\mathrm{C}$ bond distance within the layer of graphite is $154\mathrm{pm}$.
iv) ${\mathrm{SiO}}_2$ is soluble in aqueous $\mathrm{HCl}$ solution.