statement explain the first? Yes, it does. The 4s orbital
fills before the 3d orbitals because it is lower in energy.
Fill in oval CE.
- T, T Divide and conquer. Here’s what happens when calcium and
bromine react: Ca + Br 2 → CaBr 2 . Bromine’s oxidation state
decreases from 0 to −1; it is reduced. Calcium (which is oxidized) is
responsible for reducing bromine. In other words, calcium acts as a
reducing agent. Statement I is true. Look at statement II. Is mass
conserved in a chemical reaction? Yes. If it weren’t, there would be no
need to balance equations. Both statements are true. Does statement II
explain why statement I is true? No, it doesn’t. Do not fill in oval CE.
- F, T Adding an acid to water increases the hydrogen ion concentration in
the water, which means that the water’s pH is reduced. The first
statement is false and the second is true.
- F, F For a liquid to boil, the intermolecular forces in the liquid must be
overcome, not the bonds within individual molecules. When water
boils, its H 2 O molecules are still intact. While we’re considering
boiling, take a look at statement II. You need to heat water to make it
boil, so boiling absorbs, not releases, heat. Both statements are false.
- T, F Divide and conquer. A Geiger counter is used to detect radioactive
particles, so statement I is true. Be careful with statement II.
Radioactive elements have atoms with unstable nuclei. However, that
has nothing to do with an atom’s valence electrons. Radon (Rn) is a
perfect example. The nuclei of radon atoms emit alpha particles.
However, radon is a noble gas. Radon atoms have filled valence shells
and are therefore unreactive chemically. Statement II is false.
- T, T, CE
The first statement is true. If the temperature of a
substance didn’t remain constant during melting there
would be no such thing as a melting point. Instead, at a
given pressure, a substance would melt over a range of
temperatures. Statement II is also true. The heat
absorbed by the ice is being used to break
intermolecular hydrogen bonds, so we don’t see the
