9V battery and resistor are connected in series - the voltage across the resistor is < 9V. Why?
They are simulating a (more or less) real 9V battery. They've modeled the battery as an ideal voltage source of 9V with a series resistance of ~1.5 ohms. 







simulate this circuit &ndash; Schematic created using CircuitLab

If you work this out, the current is 9V/(11.5 ohms) = 0.783A, so the voltage across the 10 ohm resistor must be 7.83V.