CBSE 2022|पदार्थों का पृथक्करण -L3|Separation of Substances|Class 6 NCERT विज्ञान |8PM |Subhadra Mam

A substance ''A'' decomposes in solution following the first order kinetics. Flask I contains L of 1 M solution of A and falsk II constains 100 mL of 0.6 M solution. After 8 hr , the concentration, of A in flask I becomes 0.25 M . What will be the time for concentration of A in flask II to become 0.3 M ?

Two horizontal parallel conducting plates are kept at a separation d = 1.5 xx 10^(-2) m apart one above the other in air as shown in figure. The upper plate is maintained at a positive potential of 1.5 kV while the other plate is earthed which maintains it at zero potential. Calculate the number of electrons which must be attached to a small oil drop of mass m =4.9 xx 10^(-15) kg between the plates to maintain it at rest. Consider density of air is negligible in comparison with that ofoil. If the potential of above plate is suddenly changed to -l .5kV , what will be the initial acceleration of the charged drop? Also calculate the terminal velocity of the drop if its radius is r= 5.0 xx 10^(-6)m and the coefficient of viscosity of air is eta = 1.8 x 10--5 N-s//m^(2) [3,2g, 5.7 xx 10^(-5) m//s^(2)]