How many atoms does NH4Br have

Read the given expression. x = number of protons − number of core electrons which of the following explains the identity of x and its trends across a period? x is the effective nuclear charge, and it remains constant across a period. x is the screening constant, and it remains constant across a period. x is the effective nuclear charge, and it increases across a period. x is the screening constant, and it increases across a period.

How much energy moves onto the next level, in an energy pyramid

Evaluate this exponential expression,8. (2 + 3)2 – 42