In which of the following process , maximum increase in entropy is observed ?
Melting of ice
Sublimation of naphthalene
Condensation of water
Dissolution of salt in water
The basic structural. unit and its geometry in silicates is :
SiO2 , tetrahedral
Si , square planar
SiO2 , square planar
Si , tetrahedral
Which of the following sets of quantum numbers is not possible ?
n = 4 , l =1 , m = 0 , s =
n = 4 , l = 3 , m = - 3 , s =
n = 4 , l = 1 , m = + 2 , s =
n = 4 , l = 0 , m = 0 , s =
Solubility product of a salt AB is 1 x 10-8 M in a solution in which the concentration of A+ ions is 10-3 M .The salt , will precipitate when the concentration of B- ions is kept :
between 10-8 M to 10-7 M
between 10-7 M to 10-8 M
> 10-5 M
< 10-8 M
The pH of 10-8 M HCl solution is :
8
more than 8
between 6 and 7
slightly more than 7
C.
between 6 and 7
From H2O , [H+]=1 x 10-7 M
From HCl , [H+]= 1 x 10-8 M
Total [H+] = (1 x 10-7 + 1 x 10-8) M
= (1 x 10-7 + 0.1 x 10-7) M
= 1.1 x 10-7 M
pH = - log (1.1 x 10-7)
= 6.9586
For a reaction to be spontaneous at all temperatures ,
G and H till should be negative
G and H till should be positive
G = S = 0
H < G
For a reversible reaction ;
X (g) + 3Y (g) 2Z (g) ; H = -40 kJ , the standard entropies of X , Y and Z are 60 , 40 and 50JK mol-1 respectively .The temperature at which the above reaction attains equilibrium is about :
400 K
500 K
273K
373K