When unequal resistors are connected in series across an ideal battery, the same power is dissipated in each one. the potential difference across each is the same. the current flowing in each is the same. the equivalent resistance of the circuit is less than that of the smallest resistor. the equivalent resistance of the circuit is equal to the average of all the resistances.

the current flowing in each is the same.

Explanation:

When resistors are connected in series, they are connected in the same branch of the circuit - this means that the same current flows through each resistor.

The other options listed are wrong because:

the same power is dissipated in each one --> false: the power dissipated in each resistor is , where I is the current and R the resistance, so it depends on the value of the resistance

the potential difference across each is the same.-- > false: this is true in parallel circuits, not series circuits

the equivalent resistance of the circuit is less than that of the smallest resistor.--> false: the equivalent resistance of a series circuit is the sum of the individual resistances: , so it is larger than the resistance of the smallest resistance

the equivalent resistance of the circuit is equal to the average of all the resistances. --> false: the equivalent resistance of a series circuit is the sum of the individual resistances: , not the average