(01.06 LC) Which of the following correctly describes a compound? (4 points)
The atoms are bonded together, and the compound has different physical and
chemical properties than the individual elements.
The atoms have no set ratio for how the atoms can combine, and they are not
chemically bonded together.
The atoms can only combine in fixed ratios, and they retain their individual chemical
and physical properties.
The atoms retain their individual chemical properties, and they can only be separated
from each other by a chemical change.

As you move from right to left on the periodic table the atomic radius fill in the blank

Nebulae are enormous clouds in outer space. they are made mostly of hydrogen gas, helium gas, and dust. some nebulae glow brightly, while others do not. the stars that people see are huge, bright balls of glowing gas. they are made mostly of hydrogen and helium. which statement correctly describes other ways in which nebulae and stars are different? a. stars can form inside a nebula but a nebula can never be produced by any star. b. a star always has a higher density than a nebula. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star.

What is the wavelength of a 3*10^12 hz infrared wave a 3*10^20m b 1* 10^4m c 3*10^-3m d 1*10^-4 m