If you found tuff deposits at an igneous setting, you could conclude that the source magma had a viscosity .intrusive; high
intrusive; low
extrusive; high
extrusive; low

I'm not sure but i will try to find out

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.