A radioactive substance disintegrate its 90% in 100 days. How much time it will take to disintegrate its 99.9% ?
100 days
200 days
300 days
400 days
C.
300 days
All radioactive changes follow first order kinetics.
For the 90% completion of the reaction,
k =
=
= ...(i)
For 99.9% completion of the reaction,
k =
= ...(ii)
On putting the value of k from equation (i), we get
t = 3 × 100 day = 300 day
The Modern Periodic Table is based on the properties of elements as a function of
atomic number
atomic mass
electronegatvity
electron affinity
For the equilibrium reaction,
2SO2 (g) + O2 (g) 2SO3 (g) + H
the increase in temperature
favours the formation of SO3
favours the decomposition of SO3
does not affect the equilibrium
stops the reaction
What is the electronic configuration of O2- ion?
1s2, 2s2, 2p5, 3s1
1s2, 2s2, 2p4, 3s2
1s2, 2s2, 2p6
1s2, 2s2, 2p4
An organic compound containing C, H and N gives the following on analysis : C = 40%, H = 13.33% and N = 46.67%. What would be its empirical formula?
C2H7N
C2H7N2
CH4N
CH3N