1
AIEEE 2004
+4
-1
In a first order reaction, the concentration of the reactant decreases from 0.8 M to 0.4 M in 15 minutes. The time taken for the concentration to change from 0.1 M to 0.025 M is
A
30 minutes
B
60 minutes
C
7.5 minutes
D
15 minutes
2
AIEEE 2004
+4
-1
The rate equation for the reaction 2A + B $$\to$$ C is found to be: rate k[A][B]. The correct statement in relation to this reaction is that the
A
unit of K must be s-1
B
values of k is independent of the initial concentration of A and B
C
rate of formation of C is twice the rate of disappearance of A
D
t1/2 is a constant
3
AIEEE 2004
+4
-1
Consider the following nuclear reactions
$${}_{92}^{238}M \to {}_Y^XN + 2{}_2^4He$$
$${}_Y^XN \to {}_B^AL + 2{\beta ^ + }$$
The number of neutrons in the element L is
A
140
B
144
C
142
D
146
4
AIEEE 2004
+4
-1
The half – life of a radioisotope is four hours. If the initial mass of the isotope was 200 g, the mass remaining after 24 hours undecayed is
A
1.042 g
B
4.167 g
C
3.125 g
D
2.084 g
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