The first one is 2
The second is 1
The third is 6
And the fourth is 3
Answers:
<u>Option B. 4.</u>
Explanation:
The visible spectrum of light emitted by a sample of active or excited hydrogen atoms splits into four wavelengths that are basically four distinct levels of energy in the visible region of the spectrum. There four different wavelengths are 410 nm, 434 nm, 486 nm, and 656 nm. These show for colors according to the spectrum and wavelength violet, blue, green, and red, where 656 nm wavelength is most intense on the spectrum.
Answer: Y and Z. It's D.
Explanation: W represents evaporation, which is a physical change. X represents dissolving, which is also a physical change. If X and W aren't chemical changes, then Y and Z must be if half of the choices are.
Answer: When objects fall to the ground, gravity causes them to accelerate. Acceleration is a change in velocity, and velocity, in turn, is a measure of the speed and direction of motion. Gravity causes an object to fall toward the ground at a faster and faster velocity the longer the object falls.
Explanation: