Which of the following is true about the two resistors connected in series?

The correct answer is option 4):(All these)

Concept:

Resistances in series:

• When two or more resistances are connected one after another such that the same current flows through them are called as resistances in series.
• The net resistance/equivalent resistance (R) of resistances in series is given by: Equivalent resistance, R = R₁ + R₂
• Sum of individual voltage drop(IR) equals the applied voltage. 

​ Additional InformationResistances in parallel:When the terminals of two or more resistances are connected at the same two points and the potential difference across them is equal is called resistances in parallel.

The net resistance/equivalent resistance(R) of resistances in parallel is given by

\(\frac{1}{{{R_{eff}}}} = \frac{1}{{{R_1}}} + \frac{1}{{{R_2}}}\)