Why do d.c. voltmeter and d.c. ammeter cannot read a.c.?

What is the principle of a.c. voltmeter and a.c. ammeter?

In the circuit given below, on plugging the key, the voltmeter reads 2.0 V but ammeter reads 0.6A. The resistance of the combination is

An ammeter has 10 divisions between mark 0 and mark 2 on its scale. Which of the following reading the ammeter cannot read

The division marked on the scale of an a.c. ammeter is not equally spaced. Why?

What value of a.c. is given by an a.c. ammeter?