1

AIPMT 2000

Equilibrium constant Kp for following reaction
MgCO3(s) $\rightleftharpoons$ MgO(s) + CO2(g)
A
Kp = PCO2
B
Kp = PCO2 $\times$ ${{{P_{C{O_2}}} \times {P_{MgO}}} \over {{P_{MgC{O_3}}}}}$
C
Kp = ${{{P_{C{O_2}}} + {P_{MgO}}} \over {{P_{MgC{O_3}}}}}$
D
Kp = ${{{P_{MgC{O_3}}}} \over {{P_{C{O_2}}} + {P_{MgO}}}}$

Explanation

Kp = PCO2

As solids do not exert pressure, so their partial pressure is taken as unity.
2

AIPMT 2000

Which statement is wrong about pH and H+?
A
pH of neutral water is not zero.
B
Adding 1 N solution of CH3COOH and 1 N solution of NaOH, pH will be seven.
C
[H+] of dilute and hot H2SO4 is more than concentrated and cold H2SO4
D
Mixing solution of CH3COOH and HCl. pH will be less than 7.

Explanation

CH3COOH is weak acid while NaOH is strong base, so one equivalent of NaOH can not be neutralized with one equivalent of CH3COOH. Hence the solution of one equivalent of each does not have pH value as 7. Its pH will be towards basic side as NaOH is a strong base hence conc. of OH will be more than the conc. of H+.
3

AIPMT 2000

For any reversible reaction, if we increase concentration of the reactants, then effect on equilibrium constant
A
depends on amount of concentration
B
unchange
C
decrease
D
increase

Explanation

Equilibrium constant of a reaction is independent of the concentration of species involved in the reaction but dependent only on the temperature.
4

AIPMT 2000

Conjugate acid of NH2$-$ is
A
NH4OH
B
NH4+
C
NH2$-$
D
NH3

Explanation

NH3 after losing a proton (H+) gives NH2. So, NH3 is the conjugate acid of NH2.

Note : Conjugate acid-base pair differ only by a proton.