Does Dexmedetomidine[a sleep inducing drug] prevent injection pain due to Propofol [an anaesthetic drug]?- a study

INTERVENTION: Intervention1: Dexmedetomidine: 0.5 microgram/kg of intravenous Dexmedetomidine injected at a rate of 0.5ml/sec after applying tourniquet, then tourniquet released,IV Propofol 3ml given Intervention2: saline: 0.5 ml/kg of saline injected at a rate of 0.5ml/sec after applying tourniquet, then tourniquet released, IV Propofol 3ml given Control Intervention1: saline: 0.5 microgram/kg of intravenous saline injected at a rate of 0.5ml/sec after applying tourniquet, then tourniquet released,IV Propofol 3ml given CONDITION: Patients coming for surgery under general anaesthesia PRIMARY OUTCOME: proportion of patients attaining pain relief for injection pain due to propofol‐‐‐‐‐‐Timepoint: 5min SECONDARY OUTCOME: proportion of patients showing reduced withdrawal movements to propofol injection‐‐‐‐‐‐Timepoint: 5min INCLUSION CRITERIA: ASA I and II patients undergoing general anaesthesia