SINDH MDCAT 2015 PAPER

1. Magnesium oxide is used in making of the lining of blast furnaces. It is extracted from seawater as follows. Aqueous calcium hydroxide is added to seawater.

Ca (OH)2(aq) + MgCl2(aq) ====> Mg(OH)2(s) + CaCl2(aq)

The magnesium hydroxide is then filtered off and roasted. Which of the following comparisons between calcium and magnesium explains why magnesium hydroxide forms?

Magnesium is lower than calcium in the reactivity series.

The solubility product for Mg(OH)2 is lower than that for Ca(OH)2

The magnitude of the lattice energy of Mg(OH)2 is less than that of Ca(OH)2.

The enthalpy change of hydration for Mg^2 is less exothermic than for Ca^2

Magnesium is less electropositive than calcium.

2. When methylbenzene is treated with bromine in the presence of a catalyst, a mixture of two monobromo isomers is formed. What are the structure of these two isomers?

3. The series limit for the Balmer series of hydrogen spectrum occurs at 3664 A. Calculate Ionization energy of hydrogen atom.

NOTE: This question was cancelled

3 x 10^ 8 J

6.626 x 10^ -34 J

5.425 x 10^ -19 J

21.7 x 10^-19 J

3664 x 10^ -10 J

4. Bond energy between nitrogen atoms in N2 molecule is:

347 KJ mol ^ -1

498 KJ mol ^ -1

946 KJ mol ^ -1

242 KJ mol ^ -1

820 KJ mol ^ -1

5. The solubility product for BaSO4 at 18-25 degrees C is :

1.0 x 10^-10 mole^2 dm ^ -6

8.4 x 10^-28 mole^2 dm ^ -6

3.5 x 10^-52 mole^2 dm ^ -6

1.8 x 10^-21 mole^2 dm ^ -6

8.7 x 10^-36 mole^2 dm ^ -6

6. Atomic number of C is 6 and H is 1. How many electrons are present in 1.6 grams of methane?

2.408 x 10^23

6.02 x 10^23

1.806 x 10^23

3.01 x 10^23

1.204 x 10^23

7. A bottle of cold drink contains 200 ml liquid in which CO2 is 0.1 molar. Suppose CO2, behaves like an ideal gas, the volume of dissolved CO2, at S.T.P is:

25.5 litre

2.24 litre

0.224 litre

0.448 litre

22.4 litre

8. Surface tension in a liquid is caused by:

Greater rate of evaporation at the surface than from the interior

Greater fluidity

Reduced rate of intermolecular collisions at the surface

A lack of horizontal intermolecular forces

9. How many electrons can have the values n = 2, L = 1 and s = + 1/2 in the configuration 1s2, 2s2, 2p3

10. If uncertainity in the position of an electron is zero, the uncertainly in its momentum is:

zero

2π

Infinite

H / 4 π

SINDH MDCAT 2015 PART 7 ( CHEMISTRY )

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