Two half lives so it is 4000 years old
Answer;
B. Fluorescent lamps operate at a higher temperature than incandescent lamps.
Explanation;
-A fluorescent lamp, is a type of electric light (lamp) that uses ultraviolet emitted by mercury vapor to excite a phosphor, which emits visible light.
-A fluorescent lamp produces less heat, thus, it is much more efficient. A fluorescent bulb can produce between 50 and 100 lumens per watt. This makes fluorescent bulbs four to six times more efficient than incandescent bulbs.
-Fluorescent lamps operate best around room temperature. At much lower or higher temperatures, efficacy decreases.
Explanation:
The gravitational force equation is the following:

Where:
G = Gravitational constant = 
m1 & m2 = the mass of two related objects
r = distance between the two related objects
The problem gives you everything you need to plug into the formula, except for the gravitational constant. Let me know if you need further clarification.
When work is done and a force is transferred an object must move