2. structure of atom — Chemistry STD 11 Science — Question

$(a)$ $R_2SiO$ is repeating unit of linear silicones

$(b)$ $R$ $SiCl_3$ on hydrolysis followed by dehydration gives linear silicones

$(c)$ Silicones can be used as heat insulator

$(d)$ Silica is soluble in $HF$

The correct statement$(s)$ is/are

$2 C ( s )+ H _2( g ) \longrightarrow C _2 H _2( g ) \ \ \ \ \  \Delta H =225 \ kJ mol ^{-1} $

$2 C ( s ) \longrightarrow 2 C ( g )\ \ \ \ \ \ \Delta H =1410 \ kJ mol ^{-1} $

$H _2( g ) \longrightarrow 2 H ( g ) \ \ \ \ \ \  \Delta H =330 \ kJ mol ^{-1}$