1
AIPMT 2003
MCQ (Single Correct Answer)
+4
-1
The densities of graphite and diamond at 298 K are 2.25 and 3.31 g cm$$-$$3, respectively. If the standard free energy difference $$\left( {\Delta {G^o}} \right)$$ is equal to 1895 J mol$$-$$1, the pressure at which graphite will be transformed into diamond at 298 K is
A
11.14 $$ \times $$ 108 Pa
B
11.14 $$ \times $$ 107 Pa
C
11.14 $$ \times $$ 106 Pa
D
11.14 $$ \times $$ 105 Pa
2
AIPMT 2003
MCQ (Single Correct Answer)
+4
-1
The ions O2$$-$$, F$$-$$, Na+, Mg2+ and Al3+ are isoelectronic. Their ionic radii show
A
a significant increase from O2$$-$$ to Al3+
B
a significant decrease from O2$$-$$ to Al3+
C
an increase from O2$$-$$ to F$$-$$ and then decrease from Na+ to Al3+
D
a decrease from O2$$-$$ to F$$-$$ and then increase from Na+ to Al3+.
3
AIPMT 2003
MCQ (Single Correct Answer)
+4
-1
The velocity of Planck's constant is 6.63 $$ \times $$ 10$$-$$34 J s.

The velocity of light is 3.0 $$ \times $$ 108 m s$$-$$1. Which value is closest to the wavelength in nanometers of a quantum of light with frequency of 8 $$ \times $$ 1015 s$$-$$1 ?
A
2 $$ \times $$ 10$$-$$25
B
5 $$ \times $$ 10$$-$$18
C
$$4 \times {10^1}$$
D
3 $$ \times $$ 107
4
AIPMT 2003
MCQ (Single Correct Answer)
+4
-1
Which one of the following statements is not correct for sigma- and pi- bonds formed between two carbon atoms?
A
sigma-bond is stronger than a pi-bond.
B
Bond energies of sigma- and pi-bonds are of the order of 264 kJ/mol and 347 kJ/mol, respectively
C
Free rotation of atoms about a sigma-bond is allowed but not in case of a pi-bond.
D
Sigma-bond determines the direction between carbon atoms but a pi-bond has no primary effect in this regard.