31. The mass number of a nucleus is:

a) always less than its atomic number: b) the sum of the number of protons and neutrons present in

the nucleus; c) always more than the atomic weight; d) a fraction.

Which of the following reactions occurs most rapidly at room temperature? a. 2AgNO3 (aq) + Na2CrO4 (aq) → Ag2CrO4 (s) + 2NaNO3 (aq) b. CaO (s) + 3C (s) → CaC2 (s) + CO (g) c. SnO2 (s) + 2CO (g) → Sn (s) + 2CO2 (g) d. 2Fe (s) + O2 (g) → 2FeO (s)

What might you expect to observe from this double-displacement reaction: CoCl2 (aq) + Na2SO4 (aq) - - - > CoSO4 + 2NaCl? Edit A. CoSO4 precipitate will form. B. NaCl precipitate will form. C. one of these products will bubble out as a gas. D.

What do you call the curved, upper surface of water that commonly appears when using a graduated cylinder?. Describe what causes this?.

In general, atomic radii a. decrease from left to right in a period and increase down a group. b. increase from left to right in a period and decrease down a group. c. do not change across a period or a group. d.

Which of the following examples is a sign that a chemical change is occurring? A. the substance seems to have disappeared B. the state of the matter has changed C. the production of heat, light, and smoke

The regions within an electron cloud where electrons are located are called orbitals electron levels orbits energy levels

How many valence electrons are available for bonding in silicon

Which statement best explains why objects are pulled toward Earth's center? Earth has a magnetic force that is strongest at its core. Earth has a much greater mass than objects on its surface.

How is the sun related to nuclear electromagnetic and heat energy

How many moles are im 8.31x1023 molecules of h2so4