Which of the following did Mendeleev not believe in because he could not see them?

Mixtures

Atoms

Elements

Compounds

Which of these is not a gas? hydrogen, oxygen, gravity, or helium

Consider the following reaction and its equilibrium constant: 4 CuO (s) + CH4 (g) ⇌ CO2 (g) + 4 Cu (s) + 2 H2O (g) Kc = 1.10. A reaction mixture contains 0.22 M CH4, 0.70 M CO2 and 1.5 M H2O.

When a substance changes from one phase to another, which of the following occurs? A. The substance loses or gains heat. B. The average kinetic energy of the substance changes. C. The temperature of the substance changes. D.

The presidential election of 1928 pitted Al Smith of New York against A. Bob La Follette. B. Theodore Roosevelt. C. Herbert Hoover. D. John W. Davis.

How do solutions differ from other mixtures? A. Solutions are heterogeneous mixtures. B. Solutions do not contain more than one element. C. Each component of a solution can be seen clearly. D. One component of a solution dissolves in another.

What mechanical waves needs a medium to travel through? A. all mechanical waves need a medium to travel through B. surface waves only C. transverse and longitudinal waves only D. longitudinal and surface waves only

Which of the following statements correctly describes how Moseley's research affected the development of the periodic table? Moseley's research led to the reorganization of the elements based on their atomic mass instead of their physical appearance.

A minerals luster is produced by its ability to transmit light. Opaque minerals always have a metallic luster because they do not transmit any light. True False

The elements selenium and oxygen are both poor electrical conductors in which section of the periodic table are they found

What is the mole ratio of NaOH to Al (OH) 3