The answer is B.Let it sit
Answer:
OPTION (A) : Testing a rock sample for gold content
Explanation:
For testing a rock sample of gold content you will need a Chemist. To test the material, the sample is rubbed on black stone which will leave a mark on the stone. This mark is tested by applying aqua fortis i.e nitric acid on the mark. If the mark gets dissolve then the material is not gold. If the mark sustain the it is further tested by applying aqua regia i.e nitric acid and hydrochloric acid which will prove the sample is of gold if it gets dissolve on using hydrochloric acid. The purity of the sample can be checked by differing the concentration of the aqua regia and comparing it with the gold material of the known purity.
The answer is double displacement is the answer
Explanation:
First, we will calculate fuel consumption is as follows.

= 4526 g/s
Now, we will calculate the power as follows.
Power = Fuel consumption rate × -enthalpy of combustion
= 
=
kW
Thus, we can conclude that maximum power (in units of kilowatts) that can be produced by this spacecraft is
kW.