Answer:
To make useful chemicals and abrasives
Explanation:
Electromagnetic waves do not require a medium to travel through. They can travel through empty space or matter.
Answer:

Explanation:
First, let's find the voltage through the resistor using ohm's law:

AC power as function of time can be calculated as:
(1)
Where:

Because of the problem doesn't give us additional information, let's assume:

Evaluating the equation (1) in t=3600 (Because 1h equal to 3600s):

Explanation:
Distance travelled = Area under the line
= ut + ½ (v-u)t
Acceleration (a) = (v-u)/t and so (v-u) = at
Therefore,
Distance travelled (s) = ut + ½ (v-u)t = ut + ½ (at)t = ut + ½ at²
Thus,proved.
Answer: B
Explanation:
It's not the time it took to heat the substance, so that rules out A and C.
This means that we only have to choose between
B. the area of contact
D. the area of the substances
(since everything else in each of those answers are the same)
Area of contact matters more (e.g. an object with greater surface area is exposed to the air more, will lose/gain heat quicker than an object with less surface area).