What do you call the curved, upper surface of water that commonly appears when using a graduated cylinder? describe what causes this.

The name of this phenomenon is meniscus

It occurs due to surface tensions, which is the tendency of fluids to have elasticity because of which it fills out the least surface area possible of the container.

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.

Anions are negative charged ions