51. Element ‘A’ has electronic configuration 2, 8, 2 and element ‘B’ has 2, 8, 7. What will be the nature of the bond formed between them?
(a) Coordinate bond
(b) Covalent bond
(c) Ionic bond
(d) Metallic bond
Answer:
(c) Ionic bond
Explanation:
Element A (Magnesium) is a metal that loses 2 electrons to achieve stability. Element B (Chlorine) is a non-metal that gains 1 electron. The complete transfer of electrons from a metal to a non-metal creates an ionic bond.
52. Which of the following elements will form an acidic oxide?
(a) An element with atomic no. 11
(b) An element with atomic no. 12
(c) An element with atomic no. 16
(d) An element with atomic no. 19
Answer:
(c) An element with atomic no. 16
Explanation:
Non-metals form acidic oxides. Atomic number 16 is Sulphur, a non-metal. Elements 11 (Na), 12 (Mg), and 19 (K) are metals and form basic oxides.
53. An element has two shells and both are completely filled with electrons. This element is:
(a) Argon
(b) Neon
(c) Lithium
(d) Helium
Answer:
(b) Neon
Explanation:
The K shell holds 2 electrons and the L shell holds 8. An element with 2 fully filled shells has electrons, which is Neon.
54. Identify the correct IUPAC name for $CH_3-CH(Cl)-CH_3$:
(a) Propyl chloride
(b) Chlorobutane
(c) 1-Chloropropane
(d) 2-Chloropropane
Answer:
(d) 2-Chloropropane
Explanation:
The longest carbon chain has 3 carbon atoms (propane), and the chlorine substituent is attached to the second carbon. Therefore, the IUPAC name is 2-Chloropropane.
55. Which petroleum product has replaced coal tar for surfacing roads in modern times?
(a) Bitumen
(b) LPG
(c) Coke
(d) Lubricating oil
Answer:
(a) Bitumen
Explanation:
Bitumen, a heavy, dark fraction of petroleum, has largely replaced coal tar for metalling and surfacing roads.
