1
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+.
2
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.
3
AIPMT 2003
MCQ (Single Correct Answer)
+4
-1
For the reaction,
C3H8(g) + 5O2(g) $$ \to $$ 3CO2(g) + 4H2O(l)
at constant temperature, $$\Delta $$H $$-$$ $$\Delta $$E is
A
+ RT
B
$$-$$3RT
C
+ 3RT
D
$$-$$ RT
4
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
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