41. Of the metals $$Be,Mg,Ca$$ and $$Sr$$ of group 2 in the periodic table, which one has the least ionisation enthalpy?
A
$$Be$$
B
$$Ca$$
C
$$Mg$$
D
$$Sr$$
Answer :
$$Be$$
42. What is common between given cations and anions, $${O^{2 - }},{F^ - },N{a^ + },M{g^{2 + }},A{l^{3 + }}?$$
A
All have same ionic radii.
B
All are isoelectronic species having 10 electrons.
C
All of them belong to the third period.
D
The nature of oxides of all the ions is basic.
Answer :
All are isoelectronic species having 10 electrons.
43. The statement that is not correct for the periodic classification of element is
A
The properties of elements are the periodic functions of their atomic numbers
B
Non-metallic elements are lesser in number than metallic elements
C
The first ionisation energies of elements along a period
do not vary in a regular manner with increase in atomic number
D
For transition elements the $$d$$ -subshells are filled with
electrons monotonically with increase in atomic number
Answer :
For transition elements the $$d$$ -subshells are filled with
electrons monotonically with increase in atomic number
44. Which of the following have the same number of electrons in outermost shell?
A
Elements with atomic numbers 30, 48, 80
B
Elements with atomic numbers 14, 15, 16
C
Elements with atomic numbers 20, 30, 50
D
Elements with atomic numbers 10, 18, 26
Answer :
Elements with atomic numbers 30, 48, 80
45.
Study the given diagram of the periodic table and fill up the blanks with appropriate choice.
( → indicates the increasing trend of property. )
| $$P$$ | $$q$$ | $$R$$ | $$S$$ | |
| (a) | Ionisation enthalpy | Electron gain enthalpy | Atomic radius | Electro-negativity |
| (b) | Atomic radius | Ionisation enthalpy | Electro-negativity | Electron gain enthalpy |
| (c) | Ionisation enthalpy | Atomic radius | Electro-negativity | Electron gain enthalpy |
| (d) | Electro-negativity | Electron gain enthalpy | Ionisation enthalpy | Atomic radius |
A
(a)
B
(b)
C
(c)
D
(d)
Answer :
(a)
46. Which of the following represents the correct order of increasing first ionization enthalpy for $$Ca,Ba,S,Se\,{\text{and}}\,Ar?$$
A
$$Ca < S < Ba < Se < Ar$$
B
$$S < Se < Ca < Ba < Ar$$
C
$$Ba < Ca < Se < S < Ar$$
D
$$Ca < Ba < S < Se < Ar$$
Answer :
$$Ba < Ca < Se < S < Ar$$
47. What is the order of successive ionisation enthalpies?
A
$$I{E_{III}} > I{E_{II}} > I{E_I}$$
B
$$I{E_I} > I{E_{II}} > I{E_{III}}$$
C
$$I{E_{II}} > I{E_I} > I{E_{III}}$$
D
$$I{E_{III}} > I{E_I} > I{E_{II}}$$
Answer :
$$I{E_{III}} > I{E_{II}} > I{E_I}$$
48. Which of the following statements is not correct about the electron gain enthalpy?
A
In general, the electron gain enthalpy becomes less negative in going from top to bottom in a group.
B
The electron gain enthalpy becomes less negative in a period from left to right.
C
The elements having stable configuration like noble gases have large positive electron gain enthalpies.
D
Halogens have highest negative electron gain enthalpies.
Answer :
The electron gain enthalpy becomes less negative in a period from left to right.
49. The first element of the groups 1 and 2 are different from other members of the respective groups. Their behaviour is more similar to the second element of the following groups. What is this relationship known as?
A
Anomalous relationship
B
Periodic relationship
C
Diagonal relationship
D
Chemical relationship
Answer :
Diagonal relationship
50. An element $$'P'$$ has atomic number 56. What will be the formula of its halide?
A
$$PX$$
B
$$P{X_2}$$
C
$$P{X_3}$$
D
$${P_2}{X_3}$$
Answer :
$$P{X_2}$$