Carbogen is:

1.  mixture of ${\mathrm{O}}_2+5-10\% {\mathrm{CO}}_2$

2.  used by pneumonia patients for respiration

3.  used by victims of $\mathrm{CO}$ for respiration

4.  all of the above

If a person is injured by the shot of a gun and all the pellets could not be removed, it may cause poisoning by:

1.  Hg

2.  Pb

3.  Fe

4.  As

The carbon of microphones used in public address systems is:

1.  graphite

2.  charcoal

3.  coke

4.  lamp black

Which element of group 14 forms only one hydride?

1.  C

2.  Si

3.  Sn

4.  Pb

The thermal stability order for group 14 halides is:

1.  ${\mathrm{GeX}}_2 < {\mathrm{SiX}}_2 < {\mathrm{SnX}}_2 < {\mathrm{PbX}}_2$

2.  ${\mathrm{SiX}}_2 < {\mathrm{GeX}}_2 < {\mathrm{PbX}}_2 < {\mathrm{SnX}}_2$

3.  ${\mathrm{SiX}}_2 < {\mathrm{GeX}}_2 < {\mathrm{SnX}}_2 < {\mathrm{PbX}}_2$

4.  ${\mathrm{PbX}}_2 < {\mathrm{SnX}}_2 < {\mathrm{GeX}}_2 < {\mathrm{SiX}}_2$

The correct statement regarding polymeric silicon dioxide is -

${\mathrm{PbO}}_2$ on reaction with ${\mathrm{HNO}}_3$ gives gas:

1. ${\mathrm{NO}}_2$

2. ${\mathrm{O}}_2$

3.  ${\mathrm{N}}_2$

4.  ${\mathrm{N}}_2\mathrm{O}$

AlF₃ is soluble in HF only in the presence of KF due to the formation of:

The correct statement among the following is :

An element that cannot form ${\mathrm{MF}}_6^{3-}$ ion is-