1
AIPMT 2007
MCQ (Single Correct Answer)
+4
-1
If 60% of a first order reaction was completed in 60 minutes, 50% of the same reaction would be completed in approximately
(log 4 = 0.60, log 5 = 0.69)
A
45 minutes
B
60 minutes
C
40 minutes
D
50 minutes
2
AIPMT 2007
MCQ (Single Correct Answer)
+4
-1
Which of the following anions is present in the chain structure of silicates?
A
(Si2O$$_5^{2 - }$$)n
B
(SiO$$_3^{2 - }$$)n
C
SiO$$_4^{4 - }$$
D
Si2O$$_7^{6 - }$$
3
AIPMT 2007
MCQ (Single Correct Answer)
+4
-1
Consider the following reactions :
(i) H+(aq) + OH$$-$$(aq) = H2O(l),  $$\Delta $$H = $$-$$ X1 kJ mol$$-$$1
(ii) H2(g) + 1/2O2(g) = H2O(l),   $$\Delta $$H = $$-$$ X2 kJ mol$$-$$1
(iii) CO2(g) + H2(g) = CO(g) + H2O(l),  $$\Delta $$H = $$-$$ X3 kJ mol$$-$$1
(iv) C2H2(g) + 5/2O2(g) = 2CO2(g) + H2O(l),    $$\Delta $$H = +X4 kJ mol$$-$$1

Enthalpy of formation of H2O(l) is
A
+X3 kJ mol$$-$$1
B
$$-$$X4 kJ mol$$-$$1
C
+X1 kJ mol$$-$$1
D
$$-$$X2 kJ mol$$-$$1
4
AIPMT 2007
MCQ (Single Correct Answer)
+4
-1
An element, X has the following isotopic composition:
200X : 90%  199X : 8.0%  202X : 2.0%

The weighted average atomic mass of the naturally occuring element X is closest to
A
201 amu
B
202 amu
C
199 amu
D
200 amu