An S$.$I. engine working on Otto cycle takes the air in at $0\mathrm{.}97$ bar and $40$C$.$ The compression ratio of the cycle is $7.$ The heat supplied during the cycle is $1\mathrm{.}2$ MJ$/$kg of working fluid. Find $($a$)$ Air standard efficiency of the cycles $($b$)$ maximum temperature attained in the cycle $($c$)$ work done per kg of working fluid. $[$Ans: $=54\%,$ T$3=2353$ K$,$ WD$=648$kJ$/$kg$]$