Density = mass/volume, volume = mass/density.
Since the mass of the small cube equals 20 and the mass of the large cube is double it would be 40.
Now plug in volume = 40 g/(7.87 g/cm^3).
Thus giving you a volume 5.08 cm^3
Answer:
The resistance that will provide this potential drop is 388.89 ohms.
Explanation:
Given;
Voltage source, E = 12 V
Voltage rating of the lamp, V = 5 V
Current through the lamp, I = 18 mA
Extra voltage or potential drop = 12 V - 5 V = 7 V
The resistance that will provide this potential drop (7 V) is calculated as follows:

Therefore, the resistance that will provide this potential drop is 388.89 ohms.
I believe it is the first one
By giving them an advice and by giving them encouraging and explaining the any theory
professional is the answer
3rd