Do i get any voltage in the crystal oscillator connected externally to the atmega16l...when the mc is switched on....

 

Yes, if you connect an oscilloscope across the crystal you will see a varying voltage at the frequency of the crystal.

 

If you tried measuring it with a multimeter, you probably won't read anything, as the meter would load the circuit down too much. Even an O-scope probe can cause too much loading, preventing it from oscillating. In such cases, you can frequently get a waveform by simply holding the 'scope probe very close to the circuit, but not actually touch it.