Will a 4 ohms speaker work with 16 amplifier?

It depends on the amplifier's power rating and the speaker's impedance. If the amplifier is capable of delivering enough power to the speaker at 4 ohms, and the speaker's impedance is within the amplifier's specified range, then it will work. However, if the amplifier is not capable of delivering enough power to the speaker at 4 ohms, or if the speaker's impedance is too low for the amplifier, then it may not work properly or could damage the amplifier.