Which of the following statements about transition metals is true? . a.. they are never found uncombined in nature.. b.. they include familiar metals such as gold, silver, copper, and nickel.. c.. they are so soft that they can be cut with an ordinary knife.. d.. they are the most reactive of all the types of metals.

The answer is B.

Reason why choice A is wrong: Metals like Copper, Silver and Gold are transition metals that are found uncombined naturally. This is because they are unreactive and are placed at the bottom of the reactivity series.

Reason why I chose B as the correct You can find Gold, Silver, Copper and Nickel in the periodic table under transition metals.

Reason why choice C is wrong: ONLY Group 1 metals ( Alkali Metals ) are soft and easily cut with knife.

Reason why choice D is wrong: There are metals in Transition Metals that are unreactive such as Gold, Silver and Copper. Moreover, the most reactive metal is Potassium. These information are found in the reactivity series. Potassium is placed at the top of the reactivity series as they are the most reactive and Copper, Silver and Gold at the bottom as they are unreactive.

Letter b. They include familiar metals such as gold, silver, copper, and nickel.

Transition Metals they are found at the center of the periodic table. Note that Groups IB and IIB come after Group VIIIB in the periodic table. The elements in Group IIB are often classified as transition elements even though they do not exhibit the characteristics of these elements.

  remember that hf is only the energy of one photon. not two. not three. one.  1) 5.12 * 10^3 photons  find the energy of one photon, then determine how many photons are needed to reach the sensitivity.  e = hf  = (6.626 * 10^-34 js)(5.95 * 10^19 hz)  = 3.94247 * 10^-14 j per photon  (2.02 * 10^-10 j) / (3.94247 * 10^-14 j/photon) = 5123.69149 photons  round to three sig figs.  2) 5.77 * 10^-17 j  energy of pulse = energy per photon * number of photons  = hfn  = (6.626 * 10^-34 js)(1.66 * 10^13 hz)(5250)  = 5.774559 * 10^-17 j  round to three sig figs.  3) 4.07 * 10^8 kj/mol  10^12 pm = 1 m  c = fλ  f = c/λ  e = hf  = hc/λ  = [(6.626 * 10^-34 js)(3.00 * 10^8 m/s) / (2.94 * 10^-12 m)](1 kj/1000 j)(6.02 * 10^23 photons/mol)  = 40702571.4 kj/mol  round to three sig figs.  4) 9.94 * 10^-1 m  e = hc/λ  λ = hc / e  = (6.626 * 10^-34 js)(3.00 * 10^8 m/s) / (2.00 * 10^-25 j)  = 0.9939 m  round to three sig figs.  5) 9.06 * 10^3 photons  energy of pulse = energy per photon * number of photons  number of photons = energy of pulse / energy per photon  = energy of pulse / (hf)  = (3.87 * 10^-13 j) / [(6.626 * 10^-34 js)(6.45 * 10^16 hz)]  = 9055.23695 photons  round to three sig figs.  6) 2.78 * 10^-15 j  this is problem 1, except in reverse.  sensitivity = minumum number of photons * energy per photon  = (5930)(6.626 * 10^-34 js)(7.077 * 10^14 hz)  = 2.78070758 × 10^-15 j  round to three sig figs.

Mg-26 and mg-24 are pair of isotopes. isotopes are defined as atoms of the same element having same atomic number but different mass number. i hope that was .