The answer is D, alters the test variable, and observes the effects on other outcome variables.
(I posted the picture for a ray diagram and the first law of reflection.) The rays show the first law of reflection since everything gets reflected. Look at the picture for more:
The "sea of instability" refers to a region of elements on the periodic table that are highly unstable. These elements have extremely short half-lives that may be measured in micro- or nanoseconds. (A nanosecond is the time it takes for light to travel one foot.) This region of unstable elements surrounds the island of stability.
Answer: a) 
b) 
Explanation: Visible light is a form of electromagnetic wave.
Wavelength is defined as the distance between two successive crests of a wave. It is represented as symbol
.
Frequency is defined as the number of complete cycles happening per second. It is represented by the symbol
.
Wavelength and Frequency follow inverse relation,

where, c = speed of light = 
Wavelength and frequency of a wave is usually expressed in a range.
a) 
b) 
<span>To solve this we assume that the gas inside the balloon is an ideal </span>gas. Then, we can use the ideal gas equation which is
expressed as PV = nRT. At a constant volume pressure and number of moles of the gas
the ratio of T and P is equal to some constant. At another set of condition, the constant is still the same. Calculations are as follows:
T1/P1 = T2/P2
P2 = T2 x P1 / T1
P2 = 25 x 29.4 / 75
P2 = 9.8 kPa