326: Which of the following metals is used in the electromagnets?
(a) Soft iron
(b) Stainless steel
(c) Cobalt
(d) Copper
327: Which one of the following is the correct sequence in increasing order of molecular weights of the hydrocarbons ?
(a) Methane, ethane, propane and butane
(b) Propane, butane, ethane and methane
(c) Butane, ethane, propane and methane
(d) Butane, propane, ethane and methane
328: In an atom, the order of filling up of the orbitals is governed by
(a) Aufbau principle
(b) Heisenberg's uncertainty principle
(c) Hund's rule
(d) Pauli's exclusion principle
Explanation:
'Aufbau Principle' gives the sequence of filling of electrons into the orbitals of different atoms. It states that in the ground state of the atoms, the orbitals are filled in order of their increasing energies. The order in which the orbitals are filled is as follows : 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, .................
329: An aqueous solution of copper sulphate is acidic in nature because the salt undergoes
(a) dialysis
(b) electrolysis
(c) hydrolysis
(d) photolysis
330: Consider the following statements with reference to the Periodic Table of chemical elements :
I. lonisation potential gradually decreases along a period.
II. In a group of elements, electron affinity decreases as the atomic weight increases.
III. In a given period, electronegativity decreases as the atomic number increases.
Which of these statement(s) is/are correct ?
(a) I only
(b) II only
(c) I and III
(d) II and III
Explanation:
Ionisation potential gradually increases as the atomic number increases.