Choose the letter of the choice that best completes the statement or answers the question. identify the period and group of the element that has the electron configuration 1s22s22p63s23p3. a. period 2, group 2a c. period 3, group 3a b. period 3, group 1a d. period 3, group 5a

The given electronic configuration of the element is

The element has 15 electrons as shown by the configuration. The element's valence shell is third shell and it has five electrons in the third shell (valence shell). Elements that fall in the same group of the periodic table have same number of valence electrons. Similarly, elements of the same period in the periodic table have same number of energy levels.

For the given element, there are three energy levels or shells. So it belongs to period 3. There are 5 valence electrons, so it belongs to the group 5A.

So the correct option is: d.  period 3, group 5A

b.final

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.