6. Arrange the following elements in increasing atomic radius: Co, Ir. S. Na, Pb. l
A. Ir, Pb, Co, S. Na
B. S, Pb, fr, Co. Na
C. Na, S, Co, Pb, Ir
D. Na, Co, Ir, Pb, S
E. S. Na, Co, Pb, Ir

answer; natural resources;

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answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.