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The diagram shows an outline of the periodic table in which four elements of period 3 are labelled A, B, C and D. Which element forms an amphoteric oxide? A. Element A B. Element B C. Element C D. Element D
Which electron configuration is correct for a chromium atom, Cr, in its ground state? A. [Ar] 4s1 3d5 B. [Ar] 4s2 3d4 C. [Ar] 3d6 D. [Ar] 4s2 4d4
Phosphorus occurs as the atom and as several ions. In which row are the species arranged from the smallest radius to the largest? A. P3−, P, P3+, P5+ B. P5+, P3+, P, P3− C. P,…
What is the oxidation state of chlorine in Cl2O7? A. −7 B. +3.5 C. +7 D. +14
Which pair of elements reacts together most vigorously? A. Sodium and bromine B. Potassium and bromine C. Sodium and chlorine D. Potassium and chlorine
Which statement explains why the atomic radius decreases across period 3 from magnesium, Mg, to sulfur, S? A. The number of occupied main energy levels increases B. The shielding effect of the inner electrons decreases C. The number of protons in the nucleus…
Which properties are typical of transition elements? I. Catalytic activity II. Formation of complex ions with ligands III. A single oxidation state in all their compounds A. I and II only B. I and III only C. II and III only D. I, II and III
In which species does an atom have the oxidation state +5? I. IF5 II. H3PO4 III. N2O4 A. I and II only B. I and III only C. II and III only D. I, II and III
Which pair of elements would react together most vigorously? A. Na(s) and I2(s) B. Cs(s) and I2(s) C. Na(s) and F2(g) D. Cs(s) and F2(g)
What is the electron configuration of the Co2+ ion? A. [Ar] 3d7 B. [Ar] 4s2 3d5 C. [Ar] 4s1 3d6 D. [Ar] 4s2 3d7