Periodic table Quiz-08

Periodic table Quiz-08

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Q1.   The nature of bonding in CCl_4 and CaH_2:

•   Electrovalent in both CCl_4 and CaH_2
•  Covalent in CCl_4 and electrovalent in CaH_2
•  Electrovalent in CCl_4 and covalent in CaH_2
•  None of the above

Solution
(b) CCl_4 involves two non-metals C and Cl and thus, bonding is covalent. CaH_2 is an ionic compound as it involves alkaline earth metal.

Q2.   The correct order of second ionisation potential of carbon, nitrogen, oxygen and fluorine is:

•  C>N>O>F
•  O>N>F>C
•  O>F>N>C
•  F>O>N>C

Solution
(c) Notice configuration of N^+,C^+,O^+ and F^+.

Q3.   The only non-metal which is liquid at ordinary temperature is

•  Hg
•   Br_2
•   NH_3
•  None of these

Solution
(b) Br_2is the only non-metal which is liquid at room temperature. Hg is metal which is liquid at room temperature. NH_3is gas at room temperature.

Q4.   Which statement is wrong?

•  Hybridization is the mixing of atomic orbitals prior to their combining into molecular orbitals
•  sp^2-hybrid orbitals are formed from two p-atomic orbitals and one s-atomic orbitals
•  dsp^2- hybrid orbitals are all at 90° to one another
•  d^2 sp^3-hybrid orbitals are directed towards the corners of a regular tetrahedron

Solution
(d) d^2 sp^3- leads to octahedral geometry.

Q5.   Which is the correct order of electronegativity?

•  F>NC
•  F>N>O>C
•  F>N>O
•  F

Solution
(a) Element F O N C Electronegativity 4.0 3.5 3.1 2.5 ∴ Correct order of electronegativity F>O>N>C or F>NC

Q6.   If the ionic radii of K^+ and F^- are about 1.34 Å each, then the expected values of atomic radii of K and F should be respectively:

•  1.34 and 1.34 Å
•  2.31 and 0.64 Å
•  0.64 and 2.31 Å
•  2.31 and 1.34 Å

Solution
(b) Cations are always shorter than their parent atom, anion are always larger.

Q7.   NF_3 is :

•  Non-polar compound
•  Electrovalent compound
•  Having low value of dipole moment than NH_3
•  Having more dipole moment than NH_3

Solution
(c) Inspite of three polar bond, the lone pair of electron on N atom decreases the dipole moment of NF_3 than NH_3.

Q8.   How many bridging oxygen atoms are present in P_4 O_10?

•  6
•  4
•  2
•  5

Solution
(a))

Q9.   The increase in bond order results in:

•  Decrease in bond length and increase in bond energy
•  Decrease in bond length and bond energy
•  Increase in bond length and bond energy
•  None of the above

Solution
(a) It is a fact derived from bond order.

Q10.   The order of first ionisation energies of the element Li, Be, B, Na is

•  Li>Be>B>Na
•  Be>B>Li>Na
•  Na>Li>B>Be
•  Be>Li>B>Na

Solution
(b) Ionisation energies increase in a period on moving left to right while it decreases in a group on moving downward. The IE of Be is greater than B due to completely filled s-orbital. Hence, the order of IE is as Be>B>Li>Na.