Case Study Questions
Question 1:
Read the passage given below and answer the following questions.
Alkali metals have the lowest ionization energy in their corresponding period in periodic table because they have large size which results in a large distance between the nucleus and the outermost electron. Ionization energy of alkali metals decreases from Li to Cs due to increase in atomic size. First ionization energy of alkali metals is very low, but they have very high value of second ionization energy.
(i) Alkali metals are characterised by
(a) good conductors of heat and electricity
(b) high melting points
(c) low oxidation potentials
(d) high ionisaiton potentials.
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Answer: (a) Alkali metals are good conductors of heat and electricity but have low melting points and ionisation potentials.(ii) Metals dissolve in liquid ammonia giving coloured solutions which are conducting in nature. The colour of the solution and reason of its conductance is
(a) yellow, NH4+
(b) blue, ammoniated metals
(c) orange, [M(NH3)x]+
(d) blue, ammoniated electron.
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Answer: d(iii) Alkali metals displace hydrogen from water forming bases due to the reason that
(a) they are far above the hydrogen in electrochemical series based on oxidation potential
(b) they are far below the hydrogen in electrochemical series based on oxidation potential
(c) their ionization potential is less than that of other elements.
(d) they contain only one electron in their outermost shell.
