Page 53 - Fpgee Question And Answer 2024 Edition

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o
T = 273 + 20 = 293 K compounds will be. For the given choices, the
-5
largest Ka value is 5 x 10 therefore the correct
V = 3 x 0.08205 x 293 answer should be “b.”
740/760
-5
1250. (c) 1.74 x 10
= 74.07 liters - +
CH 3COOH + H 2O CH 3COO + H 3O
-3
-3
1246. (c) A 0.2 M solution of acetic acid has been (0.1M) (1.32 x 10 ) (1.32 x 10 )
-4
found to dissociate in 1.2 x 10 moles of hydrogen + −
and acetate: = [ H 3 O x CH3COO ]
CH3COOH
X = 1.2 x 10 moles Ka = (1.32 x 10 ) / (1 x 10 )
-4
-3 2
-1
C = 0.2 moles

Ka = 1.74 x 10
-5
2
-4 2
Ka = X = (1.2 x 10 )
C-X 0.2 - 1.2 x 10 1251.(d) 1 x 10
-4
-16

-4
[0.2 - (1.2 x 10 )] is very small to calculate and can Al(OH) Al + 3OH -
+3
be considered equal to 0.2. 3

- 3
Ksp = [Al ] x [OH ]
+3
= (1.2 x 10 ) = 7.2 x 10 Ksp = 1 x 10 x [1 x 10 ]
-4 2
-8
-4
-4 3
0.2
Ksp = 1 x 10 -16

1247. (b) The solubility product of the salt (strong 1252. (b) The word “mole” was introduced in 1896
electrolytes) can be found by the following formula: by Friedrich Wilhelm Ostwald. In Latin, mole means
“heap” or “pile.” A mole is the amount of substance
Ksp = (Ag ) x (Cl ) that contains as many elementary entities such as
-
+
= (1 x 10 ) x (1 x 10 ) atoms, molecules, or other particles as there are
-4
-4
-8
= 1 x 10 atoms in 12 gm of the carbon-12 isotope. One mole
of sodium contains the same number of atoms as
1248. (a) The surface tension of the liquid can be one mole of calcium. Many experiments over the
calculated by following formula: years have established that one mole contains
6.022 x 10 particles. This value is known as
23
S = l - (l + l ) where
S L LS Avogadro’s number.

l = surface tension of water
S
1253. (a) The molecular weight of CO is 44
2
l = surface tension of oleic acid
L gm/mole. This mass of CO is composed of 12 gm of
2
l = interfacial tension carbon and 32 gm of oxygen. Therefore, the % mass
LS
of carbon should be:
S = 72.8 - (30 + 35)

= 7.8 dynes/cm 12 x 100
= = 27%
44
If l > (l + l ) or if S > 0, liquid will spread on water,
S L LS
but not vice versa. 1254.(c) The molecular weight of Na CO is 106
2 3
gm/mole. This mass of Na CO is composed of (2 x
3
2
+
1249. (b) The degree of acidity of acid can be 23 grams) 46 gm of Na . Therefore we can say:
determined by calculating an ionization constant Ka.
The larger the Ka values, the more acidic
322