The hydrides of the first elements in groups 15-17, namely NH3, H2O and HF respectively show abnormally high values for melting and boiling points. This is due to
small size of N, O and F
the ability to form extensive intermolecular H-bonding
the ability to form extensive intramolecular H-bonding
effective van der Waals' interaction
The quantity of electricity needed to separately electrolyze 1 M solution of ZnSO4 , AlCl3 and AgNO3 completely is in the ratio of
2 : 3 :1
2 : 1 : 1
2 : 1:3
2 : 2 : 1
The amount of electrolytes required to coagulate a given amount of Agl colloidal solution (-ve charge) will be in the order
NaNO3> Al2(NO3)3 > Ba(NO3)2
Al2(NO3)3 > Ba(NO3)2 >NaNO3
Al2(NO3)3 > NaNO3 > Ba(NO3)2
NaNO3 > Ba(NO3)2 >Al2(NO3)3
Among the following observations, the correct one that differentiates between and is
both form precipitate with BaCl2, dissolves in HCl but does not.
forms precipitate with BaCl2, does not.
forms precipitate with BaCl2, does not
both form precipitate with BaCl2, dissolves in HCl but does not.
The two half-cell reactions of an electrochemical cell is given as
The value of cell EMF will be
-0.3125 V
0.3125 V
1.114 V
-1.114V
At 25C, the molar conductance of 0.007 M hydrofluoric acid is 150 mho cm2mol-1and its = 500 mho cm2mol-1. The value of the dissociation constant of the acid at the given concentration at 25°C is
7 X 10-4 M
7 X 10-5 M
9 X 10-3 M
9 X 10-4 M
To observe an elevation of boiling point of 0.05C, the amount of a solute ( mol. wt. = 100) to be added to 100 g of water (Kb= 0.5) is
2g
0.5g
1g
0.75g
A piece of wood from an archaeological sample has 5.0 counts min-1 per gram of C-14, while a fresh sample of wood has a count of 15.0 min-1g-1. If half-life of C-14 is 5770 yr, the age of the archaeological sample is
8,500 yr
9,200 yr
10,000 yr
11,000 yr
B.
9,200 yr
The formal potential of Fe3+ /Fe4+ in a sulphuric acid and phosphoric acid mixture (E° = + 0.61 V) is much lower than the standard potential (E° = + 0. 77 V). This is due to
formation of the species [FeHPO4]+
lowering of potential upon complexation
formation of the species [FeSO4]+
high acidity of the medium
Cupric compounds are more stable than their cuprous counterparts in solid state. This is because
the endothermic character of the 2nd IP of Cu is not so high
size of Cu+ is less than Cu2+
Cu2+ has stabler electronic configuration as compared to Cu+
the lattice energy released for cupric compounds
is much higher than Cu+