What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series?

An electric lamp of 100 Ω, a toaster of resistance 50 Ω, and a water filter of resistance 500 Ω are connected in parallel to a 220 V source. What is the resistance of an electric iron connected to the same source that takes as much current as all three appliances, and what is the current through it?

Judge the equivalent resistance when the following (a) 1 Ω and 106 Ω, (b) 1 Ω and 103 Ω and 106 Ω.

Redraw the circuit of Question 1, putting in an ammeter to measure the current through the resistors and a voltmeter to measure the potential difference across the 12 W resistor. What would be the readings in the ammeter and the voltmeter?

Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each, a 5 W resistor, an 8 W resistor, and a 12 W resistor, and a plug key, all connected in series.

How much energy is given to each coulomb of charge passing through a 6 V battery?