Q52. Number of molecules from the following which are exceptions to octet rule is $\_\_\_\_$\\
$\mathrm { CO } _ { 2 } , \mathrm { NO } _ { 2 } , \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } , \mathrm { BF } _ { 3 } , \mathrm { CH } _ { 4 } , \mathrm { SiF } _ { 4 } , \mathrm { ClO } _ { 2 } , \mathrm { PCl } _ { 5 } , \mathrm { BeF } _ { 2 } , \mathrm { C } _ { 2 } \mathrm { H } _ { 6 } , \mathrm { CHCl } _ { 3 } , \mathrm { CBr } _ { 4 }$\\
Q53.\\
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Consider the figure provided. 1 mol of an ideal gas is kept in a cylinder, fitted with a piston, at the position A , at $18 ^ { \circ } \mathrm { C }$. If the piston is moved to position B , keeping the temperature unchanged, then ' $x$ ' $L \mathrm {~atm}$ work is done in this reversible process. $x =$ $\_\_\_\_$ L atm . (nearest integer) [Given : Absolute temperature $\left. = { } ^ { \circ } \mathrm { C } + 273.15 , \mathrm { R } = 0.08206 \mathrm {~L} \mathrm {~atm} \mathrm {~mol} ^ { - 1 } \mathrm {~K} ^ { - 1 } \right]$