$Si$ reacts with $CH_3Cl$ at $573 \ K$ in the presence of $Cu$ powder to form methyl substituted chlorosilanes. Among the given methyl substituted chlorosilanes, whose yield is minimum?

Which of the following is a mixed oxide?

Which gas burns with a blue flame?

Consider the following statements:
$I$. In diamond,each carbon atom is $sp^3$-hybridised.
$II$. Graphite has planar hexagonal layers of carbon atoms.
$III$. Silicones being surrounded by non-polar alkyl groups are water repelling in nature.
$IV$. The order of catenation in group $14$ elements is $Si > C > Sn > Ge > Pb$.
The correct statements are:

For a good quality cement,the ratio of silica to alumina is found to be

Deep sea divers use a mixture of ....... for respiration.