Which of the following can only be separated into two or more pure substances by a chemical change?

a. an element

b. a compound

c. a homogeneous mixture

d. a heterogeneous mixture

How many atoms of oxygen in this equation : 3Ni (OH) 2

When water dissolves sugar, which process is not involved? A) dissociation B) hydration C) surface area of the solute increases

A seed crystal of diameter D (mm) is placed in a solution of dissolved salt, and new crystals are observed to nucleate (form) at a constant rate r (crystals/min).

What is the kinetic energy of the emitted electrons when cesium is exposed to UV rays of frequency 1.0*1015Hz?

Which of earths layers experiences the greatest pressure

The transfer of from one molecule to another is an oxidation-reduction reaction, or redox reaction.

Banded iron formations were caused by the production of which atmospheric gas? A) Carbon Dioxide B) Water Vapor C) Oxygen D) Nitrogen

3. Which net ionic equation describes this reaction? 3Ca (OH) 2 (aq) + 2FeCl3 (aq) → 3CaCl2 (aq) + 2Fe (OH) 3 (s) 3Ca2 + (aq) + 3OH - (aq) + Fe3 + (aq) → Fe (OH) 3 (s) + CaCl2 (aq) Fe3 + (aq) + 3OH - (aq) + 3Ca2 + (aq) → Fe (OH) 3 (s) + 3Ca2 + (aq)

How many moles of methane are produced when 25.1 moles of carbon dioxide gas react with excess hydrogen gas?

Which reaction releases the greatest amount of energy per kilogram of reactants? A) neutron + uranium-235 ➡️ barium-141 + krypton-92 + 3 neutrons B) 2C + H2 ➡️ C2H2 C) C3H8 (g) + 5O2 (g) ➡️ 3CO2 (g) + 4H2O (l) D) NaOH (aq) + HCl (aq) ➡️ NaCl (aq) +